BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:About the extension of the coordinate parametrization of radio sou
rces in VLBI
DTSTART;VALUE=DATE-TIME:20160317T083000Z
DTEND;VALUE=DATE-TIME:20160317T084500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4568@events.saip.org.za
DESCRIPTION:Speakers: Maria Karbon (GFZ)\nUsually celestial radio sources
in the celestial reference frame (CRF) catalog are divided in three catego
ries: defining\, special handling\, and others. The defining sources are t
hose used for the datum realization of the celestial reference frame\, i.e
. they are included in the No-Net-Rotation (NNR) constraints to maintain t
he axis orientation of the CRF\, and are modeled with one set of totally c
onstant coordinates. At the current level of precision\, the choice of the
defining sources has a significant effect on the coordinates. For the ICR
F2 295 sources were chosen as defining sources\, based on their geometrica
l distribution\, statistical properties\, and stability. The number of def
ining sources is a compromise between the reliability of the datum\, which
increases with the number of sources\, and the noise which is introduced
by each source. Thus\, the optimal number of defining sources is a trade-o
ff between reliability\, geometry\, and precision.\n\nIn the ICRF2 only 39
of sources were sorted into the special handling group as they show large
fluctuations in their position\, therefore they are excluded from the NNR
conditions and their positions are normally estimated for each VLBI sessi
on instead of as global parameters. All the remaining sources are classifi
ed as others. However\, a large fraction of these unstable sources show ot
her favorable characteristics\, e.g. large flux density (brightness) and a
long history of observations. Thus\, it would prove advantageous includin
g these sources into the NNR condition. However\, the instability of these
objects inhibit this. If the coordinate model of these sources would be e
xtended\, it would be possible to use these sources for the NNR condition
as well. All other sources are placed in the “others” group. This is t
he largest group of sources\, containing those which have not shown any ve
ry problematic behavior\, but still do not fulfill the requirements for de
fining sources.\n\nStudies show that the behavior of the sources can vary
dramatically in time. Hence\, each source should be modeled individually.
Considering this\, the shear amount of sources\, in our study more than 90
0 are included\, sets practical limitations.\n\nWe decided to use the mult
ivariate adaptive regression splines (MARS) procedure to parametrize the s
ource coordinates\, as they allow a great deal of automation as it combin
es recursive partitioning and spline fitting in an optimal way. The algori
thm finds the ideal knot positions for the splines and thus the best numbe
r of polynomial pieces to fit the data. We investigate linear and cubic sp
lines determined by MARS to "human" determined linear splines and their im
pact on the CRF.\n\nWithin this work we try to answer the following questi
ons: Do we still need the categorizations in stable\, special handling and
other sources? If yes\, how can we find optimal criteria for the definiti
on of these categories? Whats the best approach to find the best fitting p
olynomials? And finally\, what can we gain by introducing this type of par
ametrization within the CRF determination?\n\nhttps://events.saip.org.za/e
vent/56/contributions/4568/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4568/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aspects of ICRF-3
DTSTART;VALUE=DATE-TIME:20160316T132500Z
DTEND;VALUE=DATE-TIME:20160316T134000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4569@events.saip.org.za
DESCRIPTION:Speakers: Chopo Ma (NASA Goddard Space Flight Center)\nThe Sec
ond Realization of the International Celestial Reference Frame (ICRF) used
dual-frequency VLBI data acquired for geodetic and astrometric purposes f
rom 1979-2009 by organizations coordinated by the IVS and various precurso
r networks. Since 2009 the data set has been significantly broadened\, es
pecially by observations in the Southern Hemisphere\, and modeling of astr
onomical\, geophysical and tropospheric effects has progressed. While the
new southern data have ameliorated the north/south imbalance of observati
ons\, they appear to cause a systematic zonal declination change in the ca
talog positions. Over the three decades of the ICRF data set the effect o
f galactic aberration may be significant. Geophysical and tropospheric mo
dels also may affect the source positions. All these effects need to be a
ddressed in preparation for ICRF-3.\n\nhttps://events.saip.org.za/event/56
/contributions/4569/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4569/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Report on the current activities of GSI VLBI
DTSTART;VALUE=DATE-TIME:20160315T095500Z
DTEND;VALUE=DATE-TIME:20160315T101000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4570@events.saip.org.za
DESCRIPTION:Speakers: Ryoji Kawabata (Geospatial Information Authority of
Japan)\nThe Geospatial Information Authority of Japan (GSI) has been opera
ting Network Stations such as Tsukuba 32-m antenna\, Tsukuba Correlator\,
and Tsukuba Analysis Center. Recently we started to operate a new VGOS ant
enna\, Ishioka 13-m antenna\, which will take over the role of Tsukuba 32-
m antenna and\, on the other side\, stopped operation of the three regiona
l antennas in Japan. GSI is now being actively involved in the Asia-Oceani
a VLBI Group for Geodesy and Astrometry (AOV) by using Tsukuba 32-m and Is
hioka 13-m antenna and by correlating regular AOV sessions. We will talk o
n the current activities of GSI VLBI.\n\nhttps://events.saip.org.za/event/
56/contributions/4570/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4570/
END:VEVENT
BEGIN:VEVENT
SUMMARY:DINNER TALK: Half a century of geodetic VLBI analysis – a
personal retrospect and future outlook
DTSTART;VALUE=DATE-TIME:20160316T145000Z
DTEND;VALUE=DATE-TIME:20160316T151500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4571@events.saip.org.za
DESCRIPTION:Speakers: Harald Schuh (GFZ German Research Center for Geoscie
nces)\nThrough the analysis of geodetic VLBI data a multitude of scientifi
c topics in geodesy\, geophysics\, and astronomy can be covered. Starting
from astrometry\, relativity\, and the essential contribution of VLBI to t
he terrestrial reference frames\, geophysical effects like loading and def
ormation of the Earth’s crust\, variations of the Earth orientation para
meters\, and changes of the troposphere and ionosphere can be investigated
. Examples of some results achieved in the last decades will be given\, an
d a future outlook of VLBI analysis will be provided.\n\nhttps://events.sa
ip.org.za/event/56/contributions/4571/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4571/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The UN-GGIM Roadmap for the Global Geodetic Reference Frame
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4572@events.saip.org.za
DESCRIPTION:Speakers: Halfdan Pascal Kierulf (Norwegian Mapping Authority)
\nIn February 2015 the UN General Assembly adopted the resolution “A Glo
bal Geodetic Reference Frame for Sustainable Development” - the first re
solution recognizing the importance of a globally-coordinated approach to
geodesy. The GGRF Working Group is working on the development of a roadmap
that will describe how governments can contribute to the sustainability a
nd enhancement of the Global Geodetic Reference Frame. The ambition is tha
t UN-GGIM 6th session endorses the GGRF Roadmap in New York in August 2016
.\n\nWe will address the ongoing work with the roadmap and future plans. W
e will also discuss the opportunities and benefits of the UN resolution an
d roadmap for the development of geodesy and geodetic networks like VGOS.\
n\nhttps://events.saip.org.za/event/56/contributions/4572/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4572/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Building a new core station in Ny-Ålesund
DTSTART;VALUE=DATE-TIME:20160314T091500Z
DTEND;VALUE=DATE-TIME:20160314T093000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4573@events.saip.org.za
DESCRIPTION:Speakers: Leif Morten Tangen (Norwegian Mapping Authority)\nTh
e existing 20 m telescope in Ny-Ålesund was set in operation in 1994. The
telescope is more than 20 years now and is ready for retirement. \nWe dec
ided to build a VGOS core site with twin telescopes. The existing telescop
e is just 70 meters away from the runway and the CAA did not allow us to b
uild anything more so close. \nThe new site is about 1500 meters northwest
of the old telescope and we had to build a road with a bridge. This was f
inished summer 2014 and the construction work started in October 2014. It
is a bit challenging to do construction work during wintertime at 79 degre
e north with permafrost. During the winter\, the VLBI fundaments came up.
Station\, SLR and gravity buildings are built too. \nThis presentation wil
l show what is done until now and different solutions for the telescopes.
The telescopes shall arrive\, April 2016\n\nhttps://events.saip.org.za/eve
nt/56/contributions/4573/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4573/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Next Generation Global Geodetic Networks for GGOS
DTSTART;VALUE=DATE-TIME:20160315T070000Z
DTEND;VALUE=DATE-TIME:20160315T071500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4574@events.saip.org.za
DESCRIPTION:Speakers: Dan MacMillan (NVI\, Inc./NASA GSFC)\nWe simulated f
uture networks of VLBI+SLR sites to assess their performance. The objectiv
e is to build a global network of geographically well distributed collocat
ed next generation sites from each of the space geodetic techniques. The n
etwork is being designed to meet the GGOS terrestrial reference frame goal
s of 1 mm in accuracy and 0.1 mm/yr in stability. We simulated the next ge
neration networks that should be available in 5 years and in 10 years to a
ssess the likelihood that these networks will meet the reference frame goa
ls. Simulations were based on the expectation that 17 broadband VLBI stati
ons will be available in 5 years and 27 stations in 10 years. We also con
sider the improvement resulting from expanding the network by 6 additional
VLBI sites to improve the global distribution of the network. In the sim
ulations\, the networks will operate continuously\, but we account for sta
tion downtime for maintenance or because of bad weather. We assess the agr
eement between the estimated SLR and VLBI coordinate differences and the s
urvey ties by doing combination TRF solutions that tie the networks togeth
er only through the estimation of EOP. The strengths of VLBI and SLR allo
ws them to provide the necessary reference frame accuracy in scale\, geoce
nter\, and orientation. Even with just the +5 year network operating for
10 years\, simulations indicate that accuracies will be at the level of 0.
03 ppb\, 0.3mm\, and 10 µas. Combining the +5 year and +10 network realiz
ation will provide better estimates of accuracy.\n\nhttps://events.saip.or
g.za/event/56/contributions/4574/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4574/
END:VEVENT
BEGIN:VEVENT
SUMMARY:VERA K-band Geodetic VLBI experiment using newly developed high sp
eed sampler and recorder
DTSTART;VALUE=DATE-TIME:20160315T101000Z
DTEND;VALUE=DATE-TIME:20160315T102500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4575@events.saip.org.za
DESCRIPTION:Speakers: Takaaki Jike (National Astronomical Observatory of J
apan)\nAccording to increasing the number of observations by 1-Gbps record
ing\, geodetic VLBI solutions of VERA improve the accuracy. This is for gu
aranteeing the accuracy of VERA astrometry. However\, much more increase i
n the number of observations is already difficult by the limit of the driv
ing performance of the VERA antenna. OCTAVE series is a candidate of a nex
t-generation data processing system in VERA. Sampling/recording rate of th
e system is 8-Gbps and corresponds by 8 times the present recording rate o
f VERA. Broadening of the recording bandwidth leads to improve delay estim
ation accuracy\, and improving accuracy of geodetic solution is expected.
We performed experimental geodetic VLBI observation which used the high-sp
eed sampler and recorder. In connection with it\, we optimized selection o
f obaserved radio sources.\n\nhttps://events.saip.org.za/event/56/contribu
tions/4575/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4575/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Preliminary Results of VLBI observations of the Chang’E-3 Lunar
Lander
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4576@events.saip.org.za
DESCRIPTION:Speakers: Axel Nothnagel (Institute of Geodesy and Geoinformat
ion\, University of Bonn)\, Rüdiger Haas (Chalmers University of Technolo
gy)\nThe successful deployment of the Chang’E-3 Lander on the Moon on De
c 14th\, 2013 has opened a new window for VLBI observations of the Moon. F
ollowing proposals to the IVS Observing Program Committee\, a global IVS R
&D network augmented with two China Deep Space Stations was configured for
joint observations of the lander in a project called OCEL (Observing the
Chang’E-3 Lander with VLBI). From July 2014 to December 2015\, the Chang
’E-3 Lander was observed successfully during several 24-hour sessions. M
ore than 10 stations distributed all around the world participated in each
observing session. In this paper\, correlation results of the Beijing Aer
ospace Control Center (BACC) for sessions in 2014 are presented\, concent
rating on the software correlator\, key algorithms and observable accuracy
analysis.\nBSCS(BACC Software Correlator System) is designed to run on Be
owulf clusters consisting of commodity machines with parallel processing a
lgorithms adopted in the software. \nFor the OCEL observations\, the Delta
DOR mode was adopted\, which means a sequence of "Quasar - ChangE'3 - Quas
ar". Here\, quasars with small separation angles are preferred to elimina
te common errors as much as possible. The ChangE'3 Lander is equipped with
an X-band transponder which transfers an X-band carrier and four DOR tone
s at +/-19.25 MHz and +/-3.85 MHz in coherent modes. With a spanned bandwi
dth of 38.5 MHz\, DOR tones are recorded in five different channels. Phase
calibration (PCAL) is used to remove any offset in phase due to the BBCs
electronics of different channels. When the phases of the PCAL tones are t
oo noisy\, a strong calibrator is used to manually specify the phase of ea
ch channel. The group delay is computed by bandwidth synthesis. The prelim
inary accuracy analysis shows that the delay observables of Chang'E-3 are
better than 1 ns\, depending on the signal-to-noise ratio of the different
baselines.\n\nhttps://events.saip.org.za/event/56/contributions/4576/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4576/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tidal atmospheric loading and VLBI
DTSTART;VALUE=DATE-TIME:20160317T130000Z
DTEND;VALUE=DATE-TIME:20160317T131500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4577@events.saip.org.za
DESCRIPTION:Speakers: Anastasiia Girdiuk (TU Wien)\nThis presentation is d
edicated to the influence of diurnal atmosphere-ocean dynamics on Earth ro
tation and loading effects as observed by Very Long Baseline Interferometr
y. The first part focuses on the rotational signals associated with atmosp
heric tides\, comprising small but non-negligible oscillations in the orde
r 5 Μas. Here\, we compare tidally analysed VLBI observations against est
imates from different providers of numerical weather models. We also discu
ss the complexity of the issue that must make allowance for indirect effec
ts due to tidal pressure variations acting on the ocean.\nIn the second pa
rt\, we are investigating loading signals caused by atmospheric tides and
the associated mass variations in the ocean. Different models of the effec
t are compared with respect to their performance in a VLBI analysis\, and
strategies how to apply consistent corrections for the atmosphere and the
ocean are discussed. Moreover\, we also show VLBI results for two gravitat
ional ocean tide models\, FES2004 and FES2012\, where the latter benefits
from a much finer horizontal resolution and an improved description of hyd
rodynamic processes.\n\nhttps://events.saip.org.za/event/56/contributions/
4577/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4577/
END:VEVENT
BEGIN:VEVENT
SUMMARY:High-speed data playback of VLBI hardware correlator
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4578@events.saip.org.za
DESCRIPTION:Speakers: Jiangying Gan (Shanghai Astronomical Observatory\,CA
S)\nVLBI(Very Long Baseline Interferometry) is an important radio astronom
y\ntechnology\, is widely used in deep-space probers high-precision measur
ement. The correlator as the core data pre-processing equipment of VLBI\,
its performance is very important. At present\, China VLBI data acquisitio
n system (CDAS) can collect\ndata 2Gbps\, and multiband combination can re
ach 16Gbps or 32Gbps. For ensure the requirements of high-speed and high-p
recision\, there used Uniboard as the hardware platform\, used 10G Etherne
t as the data playback interface and 1G Ethernet as the control interface\
, research the VLBI data playback which speed up to 4Gbps for single CDAS\
, and design some pre-processing method just like data correct and data de
code specific to the VLBI data characteristic. Now we have finished the pr
eliminary system\, and there will show the design and some results.\n\nhtt
ps://events.saip.org.za/event/56/contributions/4578/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4578/
END:VEVENT
BEGIN:VEVENT
SUMMARY:WG on Galactic Aberration (WG8) meeting
DTSTART;VALUE=DATE-TIME:20160314T163000Z
DTEND;VALUE=DATE-TIME:20160314T180000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4579@events.saip.org.za
DESCRIPTION:https://events.saip.org.za/event/56/contributions/4579/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4579/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Asia-Oceania VLBI Group for Geodesy and Astrometry (AOV) meeting
DTSTART;VALUE=DATE-TIME:20160315T173000Z
DTEND;VALUE=DATE-TIME:20160315T190000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4580@events.saip.org.za
DESCRIPTION:https://events.saip.org.za/event/56/contributions/4580/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4580/
END:VEVENT
BEGIN:VEVENT
SUMMARY:IVS Analysis Workshop
DTSTART;VALUE=DATE-TIME:20160318T070000Z
DTEND;VALUE=DATE-TIME:20160318T103000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4581@events.saip.org.za
DESCRIPTION:https://events.saip.org.za/event/56/contributions/4581/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4581/
END:VEVENT
BEGIN:VEVENT
SUMMARY:VGOS Technical Committee (VTC) meeting
DTSTART;VALUE=DATE-TIME:20160318T120000Z
DTEND;VALUE=DATE-TIME:20160318T133000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4582@events.saip.org.za
DESCRIPTION:https://events.saip.org.za/event/56/contributions/4582/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4582/
END:VEVENT
BEGIN:VEVENT
SUMMARY:WG on ICRF3 meeting
DTSTART;VALUE=DATE-TIME:20160318T140000Z
DTEND;VALUE=DATE-TIME:20160318T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4583@events.saip.org.za
DESCRIPTION:https://events.saip.org.za/event/56/contributions/4583/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4583/
END:VEVENT
BEGIN:VEVENT
SUMMARY:IVS Directing Board meeting
DTSTART;VALUE=DATE-TIME:20160319T070000Z
DTEND;VALUE=DATE-TIME:20160319T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4584@events.saip.org.za
DESCRIPTION:https://events.saip.org.za/event/56/contributions/4584/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4584/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Registration
DTSTART;VALUE=DATE-TIME:20160313T140000Z
DTEND;VALUE=DATE-TIME:20160313T180000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4585@events.saip.org.za
DESCRIPTION:https://events.saip.org.za/event/56/contributions/4585/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4585/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Icebreaker Reception
DTSTART;VALUE=DATE-TIME:20160313T160000Z
DTEND;VALUE=DATE-TIME:20160313T180000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4586@events.saip.org.za
DESCRIPTION:https://events.saip.org.za/event/56/contributions/4586/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4586/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Closing Remarks
DTSTART;VALUE=DATE-TIME:20160317T144500Z
DTEND;VALUE=DATE-TIME:20160317T150000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4587@events.saip.org.za
DESCRIPTION:Speakers: Axel Nothnagel (Institute of Geodesy and Geoinformat
ion\, University of Bonn)\nhttps://events.saip.org.za/event/56/contributio
ns/4587/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4587/
END:VEVENT
BEGIN:VEVENT
SUMMARY:INVITED TALK: Current Trends and Challenges in Satellite La
ser Ranging
DTSTART;VALUE=DATE-TIME:20160314T071500Z
DTEND;VALUE=DATE-TIME:20160314T074000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4588@events.saip.org.za
DESCRIPTION:Speakers: Graham Appleby (NERC Space Geodesy Facility\, Herstm
onceux\, UK)\nSatellite Laser Ranging (SLR) is used to measure accurately
the distance from ground stations to retro-reflectors on satellites and on
the Moon. SLR is one of the fundamental space geodetic techniques that de
fine the International Terrestrial Reference Frame (ITRF)\, which is the b
asis upon which many aspects of global change over space\, time\, and evol
ving technology are measured\; with VLBI the two techniques define the sca
le of the ITRF\; alone the SLR technique defines its origin (geocentre). T
he importance of the reference frame has recently been recognized at inter
-governmental level through the United Nations\, which adopted in February
2015 the Resolution ‘Global Geodetic Reference Frame for Sustainable De
velopment.’ \n\nLaser Ranging provides precision orbit determination and
instrument calibration/validation for satellite-borne altimeters for the
better understanding of sea level change\, ocean dynamics\, ice mass-balan
ce\, and terrestrial topography. It is also a tool to study the dynamics o
f the Moon and fundamental constants and theories. With the exception of t
he currently in-orbit GPS constellation\, all GNSS satellites now carry re
tro-reflectors for improved orbit determination\, harmonization of referen
ce frames\, and in-orbit co-location and system performance validation\; t
he next generation of GPS satellites due for launch from 2019 onwards will
also carry retro-reflectors. The ILRS delivers weekly realizations that a
re accumulated sequentially to extend the ITRF and the Earth Orientation P
arameter series with a daily resolution. SLR technology continues to evolv
e toward the next generation laser ranging systems and it is expected to s
uccessfully meet the challenges of the GGOS2020 program for a future Globa
l Space Geodetic Network. Ranging precision is improving as higher repetit
ion rate\, narrower pulse lasers and faster detectors are implemented with
in the network. Automation and pass interleaving at some stations is expan
ding temporal coverage and greatly enhancing efficiency. Discussions are o
ngoing with some missions that will allow the SLR network stations to prov
ide crucial\, but energy-safe\, range measurements to optically vulnerable
satellites. New retroreflector designs are improving the signal link and
enable daylight ranging that is now the norm for many stations. We will di
scuss many of these laser ranging activities and some of the tough challen
ges that the SLR network currently faces.\n\nhttps://events.saip.org.za/ev
ent/56/contributions/4588/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4588/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Difxcalc: Calc11 for the DiFX Correlator
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4589@events.saip.org.za
DESCRIPTION:Speakers: David Gordon (NVI\, Inc./GSFC)\nDifxcalc is a versio
n of calc11 modified specifically for the\nDiFX correlator. It is a replac
ement for the calc9.1\n'calcserver' currently in use. To create difxcalc\,
all\nof the Mark3 database handler calls were removed from calc11\nand ne
w input\, output and initialization modules were\nwritten and the flow of
the program was modified\nfor correlator usage. Difxcalc takes as its\ninp
ut the .calc files that are created in the difx\nprocessing stream and dir
ectly outputs the .im\ncorrelator model files. It can handle jobs with\nmu
ltiple scans and multiple phase centers. Difxcalc\nalso contains near-fiel
d models\, which will allow\neasier correlation of spacecraft or other obj
ects in\nthe solar system. We will outline the structure of\ndifxcalc and
list the differences from the calc9.1\n'calcserver' and from the calc11 da
tabase version.\nResults of various tests and comparisons will also\nbe pr
esented.\n\nhttps://events.saip.org.za/event/56/contributions/4589/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4589/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Status of the X/S Source Catalog
DTSTART;VALUE=DATE-TIME:20160317T071500Z
DTEND;VALUE=DATE-TIME:20160317T073000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4590@events.saip.org.za
DESCRIPTION:Speakers: David Gordon (NVI Inc./GSFC)\nThe current state of t
he X/S source catalog is presented\nand compared to ICRF2. There are curre
ntly ~60% more observations\nand ~30% more sessions than were used for ICR
F2. An ICRF made\ntoday would have ~20% more sources than ICRF2 and the av
erage inflated\nformal errors would be ~2.4 times better than ICRF2. Much
of this\nimprovement has come from the VCS-II campaign on the VLBA\, in\nw
hich the average inflated formal errors of 2062 sources were\nreduced by a
factor of 3.7 and 324 new sources were added.\nAdditional new sources hav
e come from the RDV/RV\, CRF\, AUST\, AUA\,\nand AOV sessions. In addition
to the current\nstatus\, we will present some of the additional goals\nfo
r the X/S catalog before ICRF3 in 2018. This includes\nimproving the posit
ions of a limited number of sources\nfor Gaia alignment and for X/Ka compa
risons.\n\nhttps://events.saip.org.za/event/56/contributions/4590/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4590/
END:VEVENT
BEGIN:VEVENT
SUMMARY:VLBI observations of GNSS signals on the baseline Hobart-Ceduna
– First results
DTSTART;VALUE=DATE-TIME:20160317T141500Z
DTEND;VALUE=DATE-TIME:20160317T143000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4591@events.saip.org.za
DESCRIPTION:Speakers: Andreas Hellerschmied (Technische Universität Wien)
\nThe observation of GNSS satellites with the geodetic VLBI system is an i
nteresting approach which offers a variety of new possibilities. Promising
applications can be found\, among others\, in the field of inter techniqu
e ties. Such observations provide possibilities to directly connect the dy
namic GNSS and the kinematic VLBI reference frame\, which may result in im
proved future ITRF realizations. In our research we are trying to apply ob
servation strategies\, which are commonly used in geodetic VLBI\, i.e. the
main observables are group delay values derived from direct observations
and the subsequent correlations of GNSS satellite signals. However\, data
acquisition schemes for VLBI satellite observations are still at an experi
mental stage. Further research is required to establish an operational pro
cess chain\, similar to that applied for standard observations of natural
radio sources.\n\nWe successfully carried out several experiments in 2015
on the Australian baseline Ceduna-Hobart. During these sessions\, with a f
ew hours duration each\, GNSS satellites (GLONASS and GPS) were observed i
n the L1 and L2 band along with natural radio sources for calibrations. Al
l experiments were based on VEX-formatted schedule files created with the
satellite scheduling module in the Vienna VLBI Software (VieVS). These con
trol files implement a satellite tracking scheme which is based on stepwis
e antenna repositioning using sequences of discrete celestial coordinates.
The recorded data were successfully correlated with the DiFX correlator s
oftware in combination with a suitable input model for near field targets.
A preliminary analysis of the group delay measurements derived with the A
IPS software suite was carried out with VieVS. \n\nWithin this contributio
n we will give an insight into the applied data acquisition schemes\, from
scheduling\, over correlation to data analysis\, and we will present late
st results.\n\nhttps://events.saip.org.za/event/56/contributions/4591/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4591/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The progress of VLBI digital backend in SHAO
DTSTART;VALUE=DATE-TIME:20160316T081500Z
DTEND;VALUE=DATE-TIME:20160316T083000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4592@events.saip.org.za
DESCRIPTION:Speakers: renjie zhu (Shanghai Astronomical Observatory\, Chin
ese Academy of Science)\nAbstract: Shanghai Astronomical Observatory(SHAO)
has started to development VLBI digital backend in 2004. And since 2010\,
the first generation of digital backends named CDAS(Chinese VLBI Data Acq
uisition System) have been installed in CVN VLBI stations and applied in s
everal projects. This presentation will introduce the history\, the curren
t status and the future of the VLBI digital backends developed by SHAO.\n\
nhttps://events.saip.org.za/event/56/contributions/4592/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4592/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Operating Experience of Broadband Acquisition System on RT-13 Radi
o Telescopes
DTSTART;VALUE=DATE-TIME:20160314T120000Z
DTEND;VALUE=DATE-TIME:20160314T121500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4593@events.saip.org.za
DESCRIPTION:Speakers: Evgeny Nosov (IAA RAS)\nBroadband Acquisition System
(BRAS) was designed to digitize wideband signals from receivers of radio
telescopes\, pack the digital samples into VDIF frames and transmit them t
hrough 10G Ethernet interface. The system has been installed in Badary and
Zelenchukskaya observatories on the recently constructed 13-meters RT-13
radio telescopes in February–March 2015. Since November 2016\, IAA RAS p
erforms regular observations with RT-13 equipped with BRAS. Besides\, BRAS
has been used in several international observations. The talk will descri
be both the structure and performance of BRAS as well as the operation res
ults.\n\nhttps://events.saip.org.za/event/56/contributions/4593/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4593/
END:VEVENT
BEGIN:VEVENT
SUMMARY:E-GRIP: A Highly Elliptical Orbit Satellite Mission for Co-locatio
n in Space
DTSTART;VALUE=DATE-TIME:20160317T131500Z
DTEND;VALUE=DATE-TIME:20160317T133000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4594@events.saip.org.za
DESCRIPTION:Speakers: Markus Rothacher (ETH Zurich)\nIn recent years much
effort has been undertaken to combine space geodetic observations on-board
satellites\, known as co-location in space. Whereas for SLR and GNSS\, co
-locations on-board satellites already exist (LEO\, GNSS)\, no such satell
ites are allowing at present for VLBI observations. In order to cure this
situation new satellite missions like GRASP are considered\, new observati
on concepts like tracking of GNSS L-band signals were implemented\, and at
some telescopes receiver chains were modified. However\, evaluating today
’s situation\, only a few experimental GNSS L-band observations were con
ducted\, whereas the majority of radio telescopes participating in the IVS
cannot observe these. Future VLBI observations to the proposed GRASP miss
ion will be possible for nearly all radio telescopes but\, due to the low
orbit\, only for short baselines.\nIn this presentation we will introduce
a new mission: the Einstein Gravitational Red-shift Probe (E-GRIP). The sc
ientific objectives of E-GRIP are the measurement of the space-time curvat
ure around the Earth and the performance of multiple tests of general rela
tivity. Therefore\, E-GRIP will fly in a highly eccentric orbit (e>0.6\, a
pogee>35000km) and will carry a narrow- and a wide-angle microwave link (b
oth at X- and K-band)\, two GNSS antennas\, an SLR retro-reflector array\,
and a space hydrogen maser. Consequently\, E-GRIP could act as a co-locat
ion satellite with optimal observation conditions for VLBI. Beyond a missi
on overview\, we will present results from extended VLBI simulations conce
rning link budget\, visibilities\, and achievable station coordinate resul
ts. We will also discuss the benefits for VLBI compared to co-location on
GRASP and on GNSS satellites in terms of visibility and station coordinate
accuracy. In addition\, we will show the feasibility of co-located GNSS a
nd SLR observations for this highly elliptical orbit.\n\nhttps://events.sa
ip.org.za/event/56/contributions/4594/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4594/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vienna contribution to the ICRF3
DTSTART;VALUE=DATE-TIME:20160317T070000Z
DTEND;VALUE=DATE-TIME:20160317T071500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4595@events.saip.org.za
DESCRIPTION:Speakers: David Mayer (Technische Universität Wien)\nThe curr
ent realisation of the celestial reference frame\, the ICRF2\, was publish
ed 2009. Since then the VLBI technique evolved. New stations were implemen
ted and the amount of data from the Southern Hemisphere increased dramatic
ally. The demands on accuracy of the celestial reference frame are higher
than ever\, with the GAIA mission providing a catalogue in the visible spe
ctrum with comparable accuracy. These advances in the VLBI technique and n
ew demands on accuracy entail the necessity of a new version of the celest
ial reference frame which will be called ICRF3. We will report on the prog
ress and plans of the Vienna group to estimate such a reference frame. Fur
thermore\, we will discuss issues which arise during the estimation proces
s such as a declination bias.\n\nhttps://events.saip.org.za/event/56/contr
ibutions/4595/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4595/
END:VEVENT
BEGIN:VEVENT
SUMMARY:VLBI processing at ESOC\, the last piece for generating an indepen
dent reference frame
DTSTART;VALUE=DATE-TIME:20160316T123000Z
DTEND;VALUE=DATE-TIME:20160316T124500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4596@events.saip.org.za
DESCRIPTION:Speakers: Claudia Flohrer (ESOC - Navigation Support Office\,
Darmstadt\, Germany)\nESOC’s Navigation Support Office is providing the
geodetic reference for ESA missions and as leader of the Galileo Geodetic
Service Provider (GGSP) consortium\, also for Galileo. The Navigation Supp
ort Office has demonstrated its expertise in the processing of various spa
ce-geodetic techniques\, such as GNSS\, SLR and DORIS and their combinatio
n on the observation level. Nevertheless\, the last and vital piece missin
g for the generation of an independent reference frame is VLBI\, which is
required to define the Earth’s orientation. \nESOC’s Navigation Sup
port Office is currently extending its expertise to VLBI processing and an
alysis. We are enhancing the processing capabilities of our work horse sof
tware package NAPEOS for VLBI tracking data. \nThis capability will put us
in the position to combine all space-geodetic techniques with one single
software package at the observation level. The combination of the differen
t techniques brings together the strengths of the individual techniques.
The satellite techniques GNSS\, SLR and DORIS are able to determine the Ea
rth’s centre of mass\, the X- and Y-pole offsets and rates and the Lengt
h of Day. However\, VLBI is the only technique able to accurately determin
e universal time (UT1-UTC) and the celestial pole offsets.\nThe processing
of VLBI tracking data will complete ESOC’s capabilities in generating a
n independent reference frame for ESA missions. It will allow us to contri
bute to the IERS service for UT1-UTC and for the celestial pole offset\, w
hilst at the same time to reduce our dependency on this service. And last
but not least our software NAPEOS would become the first software combinin
g all four geodetic techniques on the observation level and thus supportin
g GGOS\, the Global Geodetic Observing System\, to get a better understand
ing of our living planet.\nWe will present an overview of the current stat
us of the VLBI processing at ESOC and will give an outlook on our future p
lans.\n\nhttps://events.saip.org.za/event/56/contributions/4596/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4596/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Progress on VLBI Ecliptic Plane Survey
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4612@events.saip.org.za
DESCRIPTION:Speakers: Fengchun Shu (Shanghai Astronomical Observatory)\nTh
e goal of VLBI Ecliptic Plane Survey (VEPS) is to increase the number of c
alibrator radio sources within 7.5 degree of the ecliptic plane by surveyi
ng a complete sample of sources with single dish flux densities at 5 GHz g
reater than 50 mJy. A dense grid of calibrators along ecliptic plane with
very accurate coordinates is required for many applications\, including ob
servations of spacecrafts in the phase referencing mode. Such observations
are used for spacecraft navigation\, improvement of planet ephemerides an
d determination of the Moon’s libration. The VEPS observing program is u
nderway with participation of 3 core Chinese VLBI stations: Seshan25\, Kun
ming and Urumqi\, and several international stations that join on ad hoc b
asis. We will present the current status of the VEPS observing program and
show preliminary results.\n\nhttps://events.saip.org.za/event/56/contribu
tions/4612/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4612/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Completing the K-band Celestial Reference Frame in the North.
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4597@events.saip.org.za
DESCRIPTION:Speakers: Aletha de Witt (Hartebeesthoek Radio Astronomy Obser
vatory)\nK-band (22 GHz) radio observations have the potential to form the
basis for the most accurate celestial reference frame ever constructed. R
elative to the standard S/X (2.3/8.4 GHz) observing bands\, K-band is expe
cted to exhibit a reduction in extended source morphology and core-shift.
This reduction in astrophysical systematics should allow for a more stable
celestial reference frame at K-band and should also be advantageous in ty
ing the VLBI radio frame to the Gaia optical frame. The current K-band cat
alogue consists of only 274 sources from a few VLBA sessions and uncertain
ties in source positions at the ~100 micro-arcsecond level. Modern 2 Gbps
data rates are 16 times better than previous observations\, yielding a fou
r fold increase in sensitivity. Southern observations to reduce astrometri
c systematics and to complete the sky coverage at K-band are under way. Ho
wever\, new astrometric and imaging observations are also required in the
North to improve K-band precision and spatial coverage\, and to map the in
trinsic source structure so that their astrometric quality can be evaluate
d. A proposal for astrometric and imaging observations using the Very Long
Baseline Array (VLBA) at K-band have been approved. We discuss some of o
ur first results from our K-band VLBA campaign.\n\nhttps://events.saip.org
.za/event/56/contributions/4597/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4597/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Optimizing the African VLBI Network for Astronomy and Geodesy
DTSTART;VALUE=DATE-TIME:20160315T102500Z
DTEND;VALUE=DATE-TIME:20160315T104000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4598@events.saip.org.za
DESCRIPTION:Speakers: Aletha de Witt (Hartebeesthoek Radio Astronomy Obser
vatory)\nCurrently SKA-SA and HartRAO are converting the redundant 34-m te
lecommunications antenna in Ghana to a radio telescope. The Ghanaian radi
o telescope will be the second element\, HartRAO the first\, of what will
become the African VLBI Network (AVN). There are 29 documented 30-m class
telecommunications antennas in 19 African countries (though some have bee
n destroyed). It is proposed that more of these can be converted and added
to the AVN. Each addition will improve the present global VLBI networks\
; some will have greater impact than others. Currently there are plans\,
and limited funding\, to convert two more antennas in Kenya and Zambia. I
t is presently proposed that each of these new AVN stations will be equipp
ed with the same receivers as Ghana\, a 5 and 6.7 GHz receivers and later
a 1.4 - 1.7 GHz receiver. New radio telescopes may also be built. However\
, no significant evaluation of the optimization of the AVN has been compl
eted. Such an analysis will inform which to convert first\, where to build
new stations and what next-generation instruments and receivers they shou
ld have.\n\nIn this presentation we re-visit the scientific justifications
for the AVN including both astronomical and geodetic science. We analyse
weather station\, GPS and satellite weather data for each telecommunicati
ons antenna in Africa to determine the frequency limitations at each. A Go
ogle-based assessment of the possible radio frequency interference environ
ment is made. We also generate UV-coverage plots for existing VLBI network
s together with potential AVN locations to get an idea of the density and
distribution of the UV tracks and the imaging quality that may be obtained
. In addition we simulate some geodetic observations to asses the contribu
tion of AVN antennas to geodetic VLBI products in current and future netwo
rks. With this data we attempt to optimize the AVN for each science case\,
both astronomical and geodetic. We discuss the potential contributions th
e AVN might make to current global geodetic and astronomical experiments\,
as well as what a stand-alone AVN can do. We also discuss possible statio
ns of interest for high-frequency radio astronomy and astrometry\, possibl
e sites for future VGOS antennas and where collocation of other geodetic i
nstruments can be implemented.\n\nhttps://events.saip.org.za/event/56/cont
ributions/4598/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4598/
END:VEVENT
BEGIN:VEVENT
SUMMARY:El Nino and VLBI measured LOD
DTSTART;VALUE=DATE-TIME:20160317T121500Z
DTEND;VALUE=DATE-TIME:20160317T123000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4599@events.saip.org.za
DESCRIPTION:Speakers: John Gipson (NVI Inc/GSFC NASA)\nShort term (daily t
o annual) variations in LOD are highly correlated with Atmospheric Angular
Momentum. It has been known since the late 1980s and early 1990s that yo
u could detect the effect of El Nino in the Length of Day (LOD). I review
these results\, paying particular attention to the current El Nino which i
s still developing\, and is one of the strongest ever recorded. I look at
correlation with Modified Enso Index and VLBI measured LOD. I also discus
s the cumulative effect of the El Nino on UT1.\n\nhttps://events.saip.org.
za/event/56/contributions/4599/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4599/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Unveiling the VGOS Signal Chain at the Kokee Park Geophysical Obse
rvatory
DTSTART;VALUE=DATE-TIME:20160314T101500Z
DTEND;VALUE=DATE-TIME:20160314T103000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4600@events.saip.org.za
DESCRIPTION:Speakers: Ganesan Rajagopalan (MIT Haystack Observatory)\nMIT
Haystack Observatory\, as part of the NASA Space Geodesy Program\, is deli
vering the first VGOS-compliant Signal Chain to the Kokee Park Geophysical
Observatory (KPGO)\, Hawaii\, and will soon be integrating and commission
ing the KPGO 12-m station.\n\nWe will describe the Signal Chain subsystems
and highlight the design and performance of the cryogenically cooled fron
tend. This incorporates a broadband Quad Ridge Flared Horn (QRFH) feed and
Indium Phosphide low-noise amplifiers\, both developed by the California
Institute of Technology. The talk will also cover the design and performan
ce of a Cable Delay Measurement System (CMDS) and the salient features of
a Calibrator module that enables phase and noise calibration as well as th
e cable delay measurements.\n\nWe expect to present some early results fro
m the commissioning phase of KPGO including aperture efficiency\, SEFD acr
oss the band\, and delay stability. We will also discuss possible approach
es towards RFI mitigation\, enhanced receiver sensitivity and dynamic rang
e\, and other forward-looking technologies.\n\nhttps://events.saip.org.za/
event/56/contributions/4600/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4600/
END:VEVENT
BEGIN:VEVENT
SUMMARY:IVS Primary Data Center and Analysis Center at BKG
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4601@events.saip.org.za
DESCRIPTION:Speakers: Dieter Ullrich (BKG)\nThe BKG (Federal Agency for Ca
rtography and Geodesy) Data Center is one \nof the three IVS Primary Data
Centers. It archives\nall VLBI related data of IVS components and provides
public access for \nthe community.\n\nThe VLBI Analysis Group of BKG is p
art of the jointly operated IVS \nAnalysis Center of BKG and the Institute
for Geodesy and\nGeoinformation of the University of Bonn. The BKG is res
ponsible for the \ncomputation of time series of earth orientation paramet
ers and\ntropospheric parameters\, the generation of SINEX files for 24 ho
urs VLBI \nsessions and Intensive sessions\, and quarterly updated global
solutions\nfor terrestrial reference frame and celestial reference frame r
ealizations.\n\nhttps://events.saip.org.za/event/56/contributions/4601/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4601/
END:VEVENT
BEGIN:VEVENT
SUMMARY:New generation VLBI: Intraday UT1 estimations
DTSTART;VALUE=DATE-TIME:20160315T081500Z
DTEND;VALUE=DATE-TIME:20160315T083000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4602@events.saip.org.za
DESCRIPTION:Speakers: Alexander Ipatov (Institute of Applied Astronomy RAS
)\nIAA finished work on creation of new generation radio interferometer wi
th two VGOS antennas at the Badary and Zelenchukskaya co-location stations
. The series of 48 one base 1 hour VLBI sessions (up to four sessions per
day) were performed from 04 Nov to 18 Nov 2015. Observations were carried
out using wideband S/X receivers\, 3 X-band and 1 S-band 512 MHz channels
at one or two circular polarizations. Sessions consisted of about 60 scans
with 22 seconds minimum scan duration. Stations broadband acquisition sys
tems generate 1.5-3 TB data per session which are transferred via Internet
to the IAA FX correlator. Accuracy of group delay in single channel was 1
0-20 ps what allows to use every single channel observations for geodetic
analysis without synthesis. 156 single channel NGS-cards were obtained in
total. UT1-UTC estimations give 19 µs RMS of differences when comparing w
ith the IERS finals.\n\nhttps://events.saip.org.za/event/56/contributions/
4602/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4602/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Operational VGOS Scheduling
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4603@events.saip.org.za
DESCRIPTION:Speakers: Bill Petrachenko (Natural Resources Canada)\nThe VLB
I Global Observing System (VGOS) has been designed to take advantage of ad
vances in data bandwidths\, allowing for smaller and faster antennas\, wid
er bandwidths\, and shorter observation durations. Here\, schedules for a
"realistic" VGOS network\, frequency sequences\, and expanded source lists
are presented using a new source-based scheduling algorithm. VGOS aims fo
r continuous observations which presents new operational challenges. As th
e source-based strategy is independent of the observing network\, there ar
e operational advantages which allows for more flexible scheduling of cont
inuous VLBI observations. Using VieVs\, Monte Carlo simulations of several
schedules are presented and compared with previous VGOS studies.\n\nhttps
://events.saip.org.za/event/56/contributions/4603/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4603/
END:VEVENT
BEGIN:VEVENT
SUMMARY:INVITED TALK: Activities of the IERS Working Group on Site
Survey and Co-location
DTSTART;VALUE=DATE-TIME:20160315T090000Z
DTEND;VALUE=DATE-TIME:20160315T092500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4604@events.saip.org.za
DESCRIPTION:Speakers: Sten Bergstrand (SP Technical Research Institute of
Sweden)\nThe combination of space geodetic solutions is critically reliant
on the availability of local tie vectors\, which are the relative positio
ns of the reference points of co-located space geodetic\ninstruments deter
mined by some survey technique. Tie vectors enter the combination of space
geodetic solutions effectively as a fifth technique and are not only nece
ssary for rigorous terrestrial reference frame realization but also serve
to highlight the presence of technique- and/or site-specific biases.\nWith
the ultimate objective of improving the accuracy of tie vectors as well a
s the consistency of space geodetic solutions\, the Working Group (WG) pro
vides an authoritative source of surveying methodology advice\, promotes t
echnical discussion\, provides a forum for the evaluation of existing and
new procedures and analysis strategies\, and supports the exchange of rele
vant information across GGOS and between the IAG technique services.\nThe
working group also acts as an entity of the GGOS Bureau of Networks and Ob
servations under the IERS name\, as well as of the IAG Subcommision 1.2 as
WG 1.2.1.\n\nIn the presentation\, we give examples of recent and current
work on \n• adequate terminology when discussing site surveying and
local ties\n• automatic reference point determination\n• telesco
pe deformation\n• observations of common baseline components\n•
insights to DORIS\, GNSS\, and SLR work related to local ties\n\nhttps://e
vents.saip.org.za/event/56/contributions/4604/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4604/
END:VEVENT
BEGIN:VEVENT
SUMMARY:VGOS Source Selection Criteria
DTSTART;VALUE=DATE-TIME:20160315T071500Z
DTEND;VALUE=DATE-TIME:20160315T073000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4605@events.saip.org.za
DESCRIPTION:Speakers: Bill Petrachenko (Natural Resources Canada)\nSource
structure has long been recognized as a significant risk factor for the br
oadband method. The issue of greatest concern is that structure related ph
ases and delays will lead to cycle slips during broadband phase connection
. These errors will be difficult to handle since they are both subtle to d
etect and almost certainly impossible to correct after the fact.\n\nAs the
advent of VGOS operations draws near\, criteria will be needed to generat
e lists of candidate VGOS sources that are at the same time strong enough
to be detected and simple enough not to cause broadband phase connection e
rrors. \n\nThe purpose of this study is to propose useful VGOS source sele
ction criteria and to understand their relation to broadband frequency seq
uences\, source lists\, and geodetic/astrometric performance. In order to
increase the number of available sources\, an attempt will be made to find
frequency sequences that operate reliably below the typical VGOS flux cut
-off of 250 mJ. Candidate source lists will be generated using the Bordeau
x VLBI Image Data Base (BVID) as input and geodetic/astrometric performanc
e will be predicted using the VieVS Monte Carlo simulator.\n\nhttps://even
ts.saip.org.za/event/56/contributions/4605/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4605/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aspects of relativistic geodesy within the framework of VLBI and V
GOS
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4606@events.saip.org.za
DESCRIPTION:Speakers: Ludwig Combrinck (HartRAO)\nRelativistic geodesy is
typically seen as a new type of gravity potential measurement technique us
ing very high accuracy clocks\; these clocks are more stable (by a factor
of 100 or 1000) than the hydrogen masers currently used at VLBI stations.
In modern terms however\, geodesy entails much more than just geodesy of t
he Earth\, therefore the term relativistic geodesy is re-assessed. The pos
sible contributions of VLBI stations in the framework of GGOS using VGOS a
ntennas and modernized geophysical and timing equipment are described. Tim
e transfer using VLBI and GNSS\, integrated geodetic systems\, future spac
e based missions and Lunar missions all have a roll to play in a relativis
tic geodesy which extends to the solar system and beyond. Instrumental and
network requirements are considered\, error sources and error budgets are
discussed.\n\nhttps://events.saip.org.za/event/56/contributions/4606/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4606/
END:VEVENT
BEGIN:VEVENT
SUMMARY:First implementations of new monitoring capabilities as extension
to the e-RemoteCtrl software
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4607@events.saip.org.za
DESCRIPTION:Speakers: Alexander Neidhardt (Technische Universität Münche
n\, Geodätisches Observatorium Wettzell)\nA new release of the telescope
control software e-RemoteCtrl\, which is designed to run VLBI observations
remotely\, has been extended with new monitoring capabilities. \nThe soft
ware extension is a test for further monitoring and control infrastructure
s for complete VLBI networks. The poster shows Ideas and already implement
ed elements.\n\nhttps://events.saip.org.za/event/56/contributions/4607/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4607/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Near-field VLBI for Planetary Science
DTSTART;VALUE=DATE-TIME:20160317T133000Z
DTEND;VALUE=DATE-TIME:20160317T134500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4608@events.saip.org.za
DESCRIPTION:Speakers: Bob Campbell (JIVE)\nNear-field VLBI is a radio astr
onomical technique that\, when applied to observations of spacecraft\, pro
vides unique insights into those areas of a space mission's scientific pro
gramme requiring precise determination of the spacecraft's lateral positio
n on the celestial sphere and its radial velocity. This technique was pio
neered 30 years ago with the tracking of VEGA balloons to determine the wi
nd field in the atmosphere of Venus.\n\n The Planetary Radio Interferomet
ry and Doppler Experiment (PRIDE) exploits near-field VLBI for accurate es
timation of the state-vector of a spacecraft using arrays of Earth-based r
adio telescopes. PRIDE has proven to be very efficient in a number of rec
ent VLBI experiments\, starting with tracking the descent and landing of t
he Huygens Probe in the atmosphere of Saturn's moon Titan. PRIDE has cond
ucted several observations of ESA's Venus Express mission for investigatio
ns ranging from its aero-braking maneuvers through the Venusian atmosphere
to the scintillation structure in the interplanetary medium. On 28-29 De
cember 2013\, a global VLBI campaign including over 30 stations was conduc
ted to observe Mars Express during its close fly-by of Phobos. PRIDE prov
ided measurements of the spacecraft's differential lateral position relati
ve to the ICRF background extragalactic radio sources with an accuracy of
100 to 10 μas (1σ RMS) over integration times from 60 to 1000 s. \n\n W
ith such accuracy\, PRIDE can address scientific objectives spanning\nthe
improvement of satellite ephemerides\, ultra-precise celestial mechanics\,
the study of planetary atmospheres via occultations\, and the characteriz
ation solar-wind and ionospheric effects on spacecraft transmissions. Imp
roved satellite ephemerides would in turn allow a planetary system to be t
ied more firmly into the extragalactic reference frame\, providing a major
contribution to planetary geodesy and the definition of the Solar System
reference system. \n\n In collaboration with other on-board radio science
experiments of a planetary mission\, PRIDE enhances the overall mission's
science return. We will review the technique of PRIDE and illustrate it
s capabilities in multi-disciplinary applications for planetary science mi
ssions.\n\nhttps://events.saip.org.za/event/56/contributions/4608/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4608/
END:VEVENT
BEGIN:VEVENT
SUMMARY:First results of the FAST-S/X-sessions with new VGOS antennas
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4609@events.saip.org.za
DESCRIPTION:Speakers: Alexander Neidhardt (Technische Universität Münche
n\, Geodätisches Observatorium Wettzell)\, Pablo de Vicente (Observatorio
de Yebes (IGN))\nThe organization of first fast slewing observations with
new VGOS antennas was decided during the VTC meeting at Ponta Delgada. Th
e goal was to observe S/X-schedules regularly\, using the fast slewing cap
abilities of the antennas as long as they are equipped with classic S/X-ca
pabilities. The poster/presentation discusses and shows first results of t
hese observations.\n\nhttps://events.saip.org.za/event/56/contributions/46
09/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4609/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The German Antarctic Receiving Station O’Higgins and its VLBI-ca
pabilities
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4610@events.saip.org.za
DESCRIPTION:Speakers: Christian Plötz (Bundesamt für Kartographie und Ge
odäsie)\nThe German Antarctic Receiving Station (GARS) O’Higgins starte
d in the early 1990th with regular VLBI operations. Because of its remote
position on the Antarctic Peninsula\, the VLBI observation was mostly rest
ricted to the Antarctic summer month. New equipment\, a continuous operati
on by the German Aerospace Center (DLR)\, and new realizations of observat
ion schedules may open the door for regular observations over the whole ye
ar. The poster shows the upgrades carried out in hard- and software and th
e latest results.\n\nhttps://events.saip.org.za/event/56/contributions/461
0/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4610/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Meeting of the Monitor and Control Infrastructure (MCI) group
DTSTART;VALUE=DATE-TIME:20160314T163000Z
DTEND;VALUE=DATE-TIME:20160314T180000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4611@events.saip.org.za
DESCRIPTION:https://events.saip.org.za/event/56/contributions/4611/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4611/
END:VEVENT
BEGIN:VEVENT
SUMMARY:VLBI sources in optical and radio
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4613@events.saip.org.za
DESCRIPTION:Speakers: César GATTANO (SYRTE - Observatoire de Paris)\nUnti
l now\, the main criteria for selecting geodetic sources were based on ast
rometric stability and structure at 8 GHz [Fey et al.\, 2015]. Other physi
cal characteristics\, especially at other wave-lengths\, including the opt
ical\, should also enter the selection procedure. To this aim\, we propose
to summarize all known physical caracteristics\, thanks to the use of thr
ee different catalogs : the Large Quasar Astrometric Catalogue [Souchay et
. al.\, 2015]\, the Radio Fundamental Catalogue (Petrov\, http ://astrogeo
.org/rfc/) and the Optical Characteristics of Astrometric Radio Sources [M
alkin\, 2013]. We also bring radio stability criteria derived from our own
VLBI analysis. With\nsuch a compilation\, we may identify new criterion f
or geodetic VLBI targets.\n\nhttps://events.saip.org.za/event/56/contribut
ions/4613/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4613/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The variable Earth annual retrograde nutation
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4614@events.saip.org.za
DESCRIPTION:Speakers: César GATTANO (SYRTE - Observatoire de Paris)\nVery
Long Baseline Interferometry is the only technique that can estimate Eart
h nutations with an accuracy under the milliarcsecond level. With 35 years
of geodetic VLBI observations\, the principal nutation terms caused by lu
ni-solar tides and geophysical response have been estimated. We focuse on
the variabity. Two of them present very significant amplitude and phase va
riations : the retrograde Free Core Nutation (FCN) at around 430 days peri
od and the Annual Retrograde\nNutation (ARN). Despite progresses achievied
in global circulation models\, the atmospheric and ocean excitation canno
t account for that. In particular the ARN shows an amplitude modulation of
approximately 6 years\, reminding the 6-year geomagnetc oscillation in Le
ngth of Day (LOD). Therefore we investigate possible correlation of this
modulation with the 6-year wave observed in LOD. More generally\, we sugge
st that the nutation term variability may have deep Earth causes\, and can
not be integrally attributed to surface mass redistribution.\n\nhttps://ev
ents.saip.org.za/event/56/contributions/4614/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4614/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Refinement of Rapid UT1 Estimation Derived from Tsukuba VLBI Measu
rements after 2011 Earthquake
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4615@events.saip.org.za
DESCRIPTION:Speakers: Gerald Engelhardt (BKG (Federal Agency for Cartograp
hy and Geodesy))\nThe Tsukuba station in Japan is an essential station in
the IVS Intensive series for rapid UT1 estimation. The use of this station
in rapid UT1 estimation requires a set of best-predetermined station coor
dinates but the consequences of the Earthquake in Japan in March 2011 were
such that the previously known velocity rates of the station Tsukuba were
unusable. \nSince 2012\, the VLBI group at BKG uses a method\, which solv
es this problem. This procedure was refined with respect to a newly develo
ped extrapolation to get most probable station positions of Tsukuba for th
e epochs of the Intensive sessions. The procedure is explained and could b
e successfully integrated into the technological process of operational an
alysis of post-quake Intensive sessions with station Tsukuba.\n\nhttps://e
vents.saip.org.za/event/56/contributions/4615/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4615/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Development of Hardware Correlator in SHAO
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4616@events.saip.org.za
DESCRIPTION:Speakers: zhijun xu (Shanghai Astronomical Observatory\, CAS)\
nThe hardware correlator have been used in Chinese Chang'E missions. Recen
tly\, a hardware correlator based on uniboard has been developed. This art
icle presents the development of hardware correlator at SHAO and some resu
lts.\n\nhttps://events.saip.org.za/event/56/contributions/4616/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4616/
END:VEVENT
BEGIN:VEVENT
SUMMARY:KPGO 12m Signal Chain Update\, First Light and Beyond
DTSTART;VALUE=DATE-TIME:20160314T100000Z
DTEND;VALUE=DATE-TIME:20160314T101500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4617@events.saip.org.za
DESCRIPTION:Speakers: Chet Ruszczyk (MIT Haystack Observatory)\nThe Kokee
Park Geophysical Observatory's 12m is expected to see First \nLight early
2016. A description of the integration and testing that \nwas performed
at MIT Haystack Observatory before shipping \nthe signal chain is describe
d. This is followed by a summary of the \nteams work that had to occur b
efore first light and the initial \nresults. \n\nBeyond KPGO first light f
ocuses on the commissioning summary followed \nby the road to the second i
nstallation at McDonald Texas. Here the \nfocus shifts to the expected e
nhancements to the signal chain and retrofit plans for KPGO.\n\nhttps://ev
ents.saip.org.za/event/56/contributions/4617/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4617/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Venus and Mars Express spacecraft observations with Wettzell radio
telescopes
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4618@events.saip.org.za
DESCRIPTION:Speakers: Alexander Neidhardt (Technische Universität Münche
n\, Geodätisches Observatorium Wettzell)\nThe ESA Venus and Mars Express
spacecrafts were observed at X-band with the Wettzell radio telescopes Wn
and Wz in a framework of the assessment study of the possible contribution
of the European VLBI network to the upcoming ESA deep space missions and
further projects. These observations were extended to regular weekly sessi
ons to routinely run the processing and analysis pipeline. Recorded data w
ere transferred from Wettzell to the JIVE cooperation partners for correla
tion and analysis. A high dynamic range of the detections allowed us to ac
hieve a milliHz level of the spectral resolution accuracy and extract the
phase of the spacecraft signal carrier line. Several physical parameters c
an be determined from these observational results with more observational
data collected. Apart from other results\, the measured phase fluctuations
of the carrier line at different time scales can assess to determine the
influence of the Solar wind plasma density fluctuations on the accuracy of
the astrometric VLBI observations.\n\nhttps://events.saip.org.za/event/56
/contributions/4618/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4618/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Status Report Norwegian Mapping Authority Analysis Center
DTSTART;VALUE=DATE-TIME:20160316T101000Z
DTEND;VALUE=DATE-TIME:20160316T102500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4619@events.saip.org.za
DESCRIPTION:Speakers: Ann-Silje Kirkvik (Norwegian Mapping Authority)\nThe
Norwegian Mapping Authority has been using GEOSAT to analyze 24-hour VLBI
sessions. GEOSAT was originally developed by Per Helge Andersen at the No
rwegian Research Defense Establishment\, but is now owned by Norwegian Map
ping Authority. GEOSAT is a multi-technique geodetic analysis software tha
t aims to process observations from VLBI\, SLR\, GNSS and DORIS to improve
the global geodetic reference frame. \nTo validate the VLBI model in GEOS
AT the Norwegian Mapping Authority tried to contribute to the next ITRF so
lution but encountered some major problems too close the final deadline. H
owever\, the Norwegian Mapping Authority successfully participated the VLB
I Software Comparison Campaign 2015. A quick overview of the recent activi
ties\, challenges\, priorities\, status and future plans for the GEOSAT pr
oject at the Norwegian Mapping Authority will be presented.\n\nhttps://eve
nts.saip.org.za/event/56/contributions/4619/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4619/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The impact of the broadband VLBI on the next decade
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4626@events.saip.org.za
DESCRIPTION:Speakers: Kazuhiro Takefuji (NICT)\, Mamoru Sekido (National I
nstitute of Information and Communications Technology)\nThe Kashima 34 m r
adio telescope\, the cassegrain optics is currently realized 3.2GHz to 14
GHz receiver system by installing the NINJA feed. Furthermore a direct sam
pler GALAS easily connect four 1GHz bandwidth without any analogue frequen
cy converter and phase-cal.\n VGOS\, EHT and other astronomy VLBI highly d
emand broadband system for better delay determination\, shorter integratio
n time and better SNR.\n We will report our progress of developing broadba
nd system and recent results.\n\nhttps://events.saip.org.za/event/56/contr
ibutions/4626/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4626/
END:VEVENT
BEGIN:VEVENT
SUMMARY:How to register a VGOS-radio telescope at ITU and why it is import
ant
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4656@events.saip.org.za
DESCRIPTION:Speakers: Brian Corey (MIT Haystack Observatory)\, Vincenza TO
RNATORE (Politecnico di Milano - DICA)\nA number of new VGOS-radio telesco
pes are built or under construction\, partly at new locations. VGOS radio
telescopes enable observations in the range of 2-14 GHz. For this reason V
GOS radio telescopes are much more receptive for unwanted radio frequency
interference. RFI originates from local transmitting devices as well as fr
om space based transmitting systems. Some space-borne devices may cause de
trimental radiation to VGOS receivers. It is important to register the new
sites at ITU in order to obtain administrative protection for the radio t
elescope sites and to avoid direct illuminations by strong radars. This co
ntributions explains how to achieve the registration.\n\nhttps://events.sa
ip.org.za/event/56/contributions/4656/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4656/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The new Geodetic Research Data Management System at HartRAO
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4620@events.saip.org.za
DESCRIPTION:Speakers: Glenda Coetzer (HartRAO)\nThe Hartebeesthoek Radio A
stronomy Observatory (HartRAO) participates in astronomic\, astrometric an
d geodetic Very Long Baseline Interferometry (VLBI) observations using bot
h 26- and 15-m diameter radio telescopes. These as well as additional geod
etic data from a Satellite Laser Ranger (SLR)\, Global Navigation Satellit
e System (GNSS)\, Met4 weather stations\, a new seismic network must be st
ored at HartRAO and made available to the scientific community. Some data
are e-transferred to correlators\, analysis centres and space geodesy data
providers\, while others are processed locally to produce basic data prod
ucts. The African VLBI Network (AVN) data storage and correlation will occ
ur at HartRAO as well.\n\nThe AVN correlation and seismic network will gen
erate large volumes of raw data to be stored and archived at HartRAO. The
current data storage systems are distributed and outdated\, and management
systems currently being used will not be able to handle the additional la
rge data volumes. This necessitates the design and implementation of a new
\, next-generation research data management system which combines all the
datasets into one database\, as well as cater for current and future data
volume requirements. \n\nIn terms of processing\, HartRAO is collaborating
with the CSIR Centre for High Performance Computing and we will operate a
Dell Westmere cluster containing 2880 CPU cores (61.5 TFlops)\n\nProfessi
onals from different disciplines will be working together in designing and
implementation of the new data and processing systems. A short overview o
f the project as well as a progress report will be presented.\n\nhttps://e
vents.saip.org.za/event/56/contributions/4620/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4620/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Statistic Analysis of Atmospheric Effects of Differential VLBI
DTSTART;VALUE=DATE-TIME:20160317T100000Z
DTEND;VALUE=DATE-TIME:20160317T101500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4621@events.saip.org.za
DESCRIPTION:Speakers: Shuangjing Xu (Shanghai Astronomical Observatory)\nD
uring the Chinese Lunar Mission hundreds of VLBI observations have been ca
rried\, we re-analysis all the quasar observations which used to calibrate
the satellite observables. In each observation there are two quasar scans
lasting about one hour\, we use these data by splitting them into differe
nt time intervals and doing self-calibration each other in phase-referenci
ng style to investigate the relationship of differential atmospheric delay
and different “time-switching”. In this report we will present our pr
imary result.\n\nhttps://events.saip.org.za/event/56/contributions/4621/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4621/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Automated simultaneous local ties with GNSS and robot tachymeter
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4622@events.saip.org.za
DESCRIPTION:Speakers: Sten Bergstrand (SP Technical Research Institute of
Sweden)\nWe have used GPS-based local-tie measurements simultaneously with
geo VLBI observations since 2008 during every geodetic VLBI session at Me
tsähovi. This system uses gimbal-mounted GNSS-antennas that are mounted o
n the reflector of the Metsähovi 14 m radio telescope. A similar system h
as been installed in 2013 at the Onsala 20 m radio telescope and been used
for a large number of VLBI sessions\, including e.g. the 15 day long CONT
14 campaign. In order to verify the results of the two systems\, we perfor
med a dedicated measurement campaign in the framework of the SIB60 project
\, involving both Metsähovi and Onsala. During this campaign the local ti
es at the two stations were measured simultaneously during two VLBI sessio
ns in August and September 2015 where both stations participated. The robo
t tachymeter monitoring system HEIMDALL was used for the automated classic
al monitoring of the telescopes at both stations. Moreover\, additional lo
cal terrestrial measurements were performed several times to derive the fu
ll IVS-IGS local ties at both sites. The kinematic GPS measurement at the
two stations were analyzed with two individually developed analysis progra
ms.\nWe present here the preparations of the campaign\, the measurement pr
ocess\, and preliminary results.\n\nhttps://events.saip.org.za/event/56/co
ntributions/4622/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4622/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Current status of the development and performance of OCTAVE-DAS an
d Correlator System
DTSTART;VALUE=DATE-TIME:20160314T121500Z
DTEND;VALUE=DATE-TIME:20160314T123000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4623@events.saip.org.za
DESCRIPTION:Speakers: Tomoaki Oyama (NAOJ)\nThe new VLBI observing system
(OCTAVE-DAS) have been developed based on the VSI-H and VDIF specification
s at NAOJ (National Astronomical Observatory of Japan). It consists of 1)
a high speed 1-20 Gsps 3-10 bit RF direct ADC (OCTAD) enable us to acquire
not only wide intermediate frequency but also radio frequency up to 50 GH
z and have DBBC functions for VGOS (VLBI Global Observing System)\, 2) a c
onverter (OCTAVIA and OCTAVIA2) between one 10 GigE port and four 2 Gbps i
nput and output ports conformable to VSI-H\, and 3) new recorders (OCTADIS
K\, OCTADISK2 and VSREC)have functions of both recording and playing at a
maximum rate of 32 Gbps and 4) Gbit realtime correlator (OCTACOR) and soft
ware correlator system (OCTACOR2) using GICO3 was developed by NICT. We ha
ve been upgrading the software correlator using GPGPU technology. These O
CTAVE-DAS are connected via >10 GigE network with VDIF and VSI specificati
ons. These components have been used for VERA\, JVN (Japanese VLBI network
) and Daejeon Correlator. We will report on a installation plan and a 4-ye
ar progress since the 7th IVS general meeting and results of test and scie
ntific broad-band(>8 Gbps) VLBI observations using the OCTAVE-DAS.\n\nhttp
s://events.saip.org.za/event/56/contributions/4623/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4623/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The first geodetic VLBI field-test of LIFT: a 550Km long optical f
iber link for remote antenna synchronization
DTSTART;VALUE=DATE-TIME:20160316T083000Z
DTEND;VALUE=DATE-TIME:20160316T084500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4624@events.saip.org.za
DESCRIPTION:Speakers: Matteo Stagni (IRA - INAF)\nWe present the first fie
ld-test of the implementation of a coherent optical fiber link for remote
antenna synchronization realized in Italy between the Italian Metrological
Institute (INRIM) and the Medicina radio observatory. The Medicina VLBI a
ntenna participated to the Eur137 experiment carried out in September 201
5\, in tag along mode\, using\, as reference systems\, both the local H ma
ser and a remote H maser hosted at the INRIM labs in Turin\, 550km far fro
m Medicina. In order to assess the quality of the remote clock\, the obser
ved sources were split in two sets\, each one has been observed with the a
ssociated H maser (local or remote). A system to switch automatically betw
een the two references was integrated in the antenna field system. The obs
ervations were correlated in Bonn and preliminary results are encouraging
since fringes have been detected with both time references along all the 2
4 hours of the session. The experimental set-up\, the results and the pers
pectives for future radio astronomical and geodetic experiments will be pr
esented.\n\nhttps://events.saip.org.za/event/56/contributions/4624/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4624/
END:VEVENT
BEGIN:VEVENT
SUMMARY:ivg::ASCOT: The Development of a new VLBI Software Package
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4627@events.saip.org.za
DESCRIPTION:Speakers: Thomas Artz (Institute of Geodesy and Geoinformation
\, University of Bonn)\nAlthough several fully developed VLBI software pac
kages exist already\, the VLBI group of the Institute of Geodesy and Geoin
formations of Bonn University (ivg) started implementing a new analysis to
olbox. The main reason is the need for a flexible environment\, which allo
ws for straightforward implementations of new scientific and software-rela
ted ideas for VLBI data analysis. Furthermore\, we wanted to be able to co
ntrol and understand the whole processing chain and\, last but not least\,
the developments\, which have been performed in Bonn in recent years\, sh
ould be accumulated under a unified software installation.\n\nThe software
is implemented in C++ and should finally be able to perform schedules of
VLBI sessions\, simulation of VLBI observations as well as geodetic data a
nalysis and intra-technique combination. Thus\, it is named: Analysis\, Sc
heduling and Combination Toolbox of the Institute of Geodesy and Geoinform
ations VLBI group (ivg::ASCOT). Currently\, we are able to perform single-
session data analysis in line with the IERS2010 Conventions\, at a stage w
here the ambiguities have been resolved. The VGOS-DB data format is used a
s input. Furthermore\, global solutions to derive celestial and terrestria
l reference frames can be performed on the normal equation level. This can
be done based on our single session analysis as well as with SINEX input
from other analysis centers. Intra-technique combinations of several solut
ions complete the initial functionality of the software package. In this p
aper\, we present the modelling of our toolbox as well as some key ideas o
f our processing and some first results.\n\nhttps://events.saip.org.za/eve
nt/56/contributions/4627/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4627/
END:VEVENT
BEGIN:VEVENT
SUMMARY:DOR Local-correlation Delay Model Calculation Experiment in CE-3 M
ission
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4628@events.saip.org.za
DESCRIPTION:Speakers: Yidan Huang (Shanghai Astronomical Observatory)\nThe
beacon of CE-3 satellite have several tones for communication and VLBI tr
acking. In order to improve data transferring and processing efficiency\,
we tried the local-correlation method which was different from the one use
d in CE-3 project. The Time delay model used in local-correlation experime
nt also differed from normal time delay model. The result shows that there
are a few dozen meters of discrepancy between orbit determination result
and reference orbit. The equivalent delay difference is less than 1 ns.\n\
nhttps://events.saip.org.za/event/56/contributions/4628/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4628/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Application and development of VieVS at BACC
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4629@events.saip.org.za
DESCRIPTION:Speakers: Johannes Boehm (Technische Universität Wien)\nBACC(
Beijing Aerospace Control Center)\, as the command center for the Chinese
space program\, got access to VieVS in 2011. Since 2013\, IVS VLBI data ha
s been downloaded and analyzed automatically with VieVS at BACC and the ge
odetic products will be provided firstly in the presentation. VieVS was al
so used to estimate the coordinates of new Chinese VLBI telescopes with do
mestic VLBI network in the past two years\, the preliminary results will b
e presented secondly. Furthermore\, Chinese lander on the moon has been ob
served by IVS VLBI telescopes with success already and the APOD (Atmospher
ic density detection and Precise Orbit Determination) satellite provides g
reat possibility since it carries dual-frequency GNSS (GPS/BD) receiver\,
SLR reflector and S/X band VLBI beacon. VieVS was developed at BACC to mee
t the requirements of satellite observations. Lastly EOP prediction has be
en interpolated to VieVS and the comparisons of EOP prediction will also b
een presented.\n\nhttps://events.saip.org.za/event/56/contributions/4629/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4629/
END:VEVENT
BEGIN:VEVENT
SUMMARY:ICRF sources: How good is the 'deep' southern sky
DTSTART;VALUE=DATE-TIME:20160317T091500Z
DTEND;VALUE=DATE-TIME:20160317T093000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4630@events.saip.org.za
DESCRIPTION:Speakers: Sayan Basu (University of South Africa and Hartebees
thoek Radio Astronomy Observatory\, South Africa)\nThe International Celes
tial Reference Frame (ICRF) are constructed using catalogs of extragalacti
c radio source (mainly quasars) positions measured at 2.3 and 8.4 GHz with
the Very Long Baseline Interferometry (VLBI) technique. Most extragalacti
c radio sources exhibit spatially extended structures on milliarcsecond an
d sub-milliarcsecond scales which are variable in both time and frequency
. These extended structures may contribute significant errors in the VLBI
measurements that will introduce uncertainty in the source position measur
ements. Therefore\, in order to define and maintain the celestial referenc
e frame with the highest accuracy\, efforts are required to map sources an
d to study their suitability as reference frame source on VLBI scales. \n
We will present multi-epoch imaging results of the ICRF sources in the sou
thern sky from the Celestial Reference Frame Deep South (CRDS) observing c
ampaign from the IVS. Source morphology as well as source quality aspects
will be discussed in the presentation which will give a better understand
ing of source behavior at 2.3 and 8.4 GHz observing frequencies with the V
LBI technique.\n\nhttps://events.saip.org.za/event/56/contributions/4630/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4630/
END:VEVENT
BEGIN:VEVENT
SUMMARY:VieVS 2.3 - status of the Vienna VLBI Software and plans for the f
uture
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4631@events.saip.org.za
DESCRIPTION:Speakers: Johannes Böhm (Technische Universität Wien)\nThe V
ienna VLBI Software (VieVS) is a VLBI analysis software developed and main
tained at Technische Universität Wien (TU Wien) since 2008 with contribut
ions from groups all over the world. It is used for both academic purposes
in university courses as well as for providing VLBI analysis results to t
he geodetic community. Written in a modular structure in Matlab\, VieVS of
fers easy access to the source code and the possibility to adapt the progr
ams for particular purposes.\nThe new version 2.3\, released in December 2
015\, includes several new parameters to be estimated in the global soluti
on\, such as tidal ERP variation coefficients. The graphical user interfac
e was slightly modified for an improved user functionality and\, e.g.\, th
e possibility of deriving baseline length repeatabilities. The scheduling
of satellite observations was refined\, the simulator newly includes the e
ffect of source structure which can also be corrected for in the analysis.
\nThis poster gives an overview of all VLBI-related activities in Vienna a
nd provides an outlook to future plans concerning the Vienna VLBI Software
.\n\nhttps://events.saip.org.za/event/56/contributions/4631/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4631/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vienna contribution to ITRF2014
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4632@events.saip.org.za
DESCRIPTION:Speakers: Johannes Boehm (Technische Universität Wien)\nThe n
ext realisation of the International Terrestrial Reference System\, the IT
RF2014\, is currently in preparation or under evaluation\, respectively. T
he VLBI input to ITRF2014 is provided by the International VLBI Service fo
r Geodesy and Astrometry (IVS) and consists of a combination of all analys
is center contributions. One of these single solutions is contributed by t
he Vienna special analysis center of the Department of Geodesy and Geoinfo
rmation at TU Wien. In this presentation we describe the characteristics o
f the Vienna contribution (calculated using the Vienna VLBI Software VieVS
) to ITRF2014 or VTRF2014\, respectively. We give a documentation of the i
ncluded sessions and stations as well as some statistical information whic
h show the performance of the Vienna contribution compared to the other co
ntributions to the IVS combination. In addition to that\, a single solutio
n TRF\, VieTRF2014\, which is based on the Vienna input to ITRF2014\, is p
resented and compared to previous TRF solutions.\n\nhttps://events.saip.or
g.za/event/56/contributions/4632/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4632/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The XKa Celestial Reference Frame: Assessing Accuracy
DTSTART;VALUE=DATE-TIME:20160317T081500Z
DTEND;VALUE=DATE-TIME:20160317T083000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4633@events.saip.org.za
DESCRIPTION:Speakers: Christopher Jacobs (JPL/NASA)\nObservations at X/Ka-
band are motivated by their ability to access more compact source morpholo
gy and reduced core shift relative to observations at the historically st
andard S/X-band. In addition\, the factor of four increase in interferomet
er resolution at Ka-band should resolve out some wide binary black holes w
hich are a topic of concern \nfor AGN centroid stability.\n\nGiven these m
otivations\, an X/Ka-band (8.4/32 GHz) celestial reference frame has been
constructed using a combined NASA and ESA Deep Space Network. In 124 ob
serving sessions we detected 673 sources covering the full 24 hours of ri
ght ascension and the full range of declinations. The resulting XKa median
precision is now better than the ICRF-2 precision thereby raising the que
stion of which frame is more accurate. \n\nComparison of over 500 X/Ka sou
rces in common with the S/X-band (2.3/8.4 GHz) ICRF2 produced wRMS agreem
ent of about 200 microasec. There is evidence for systematic errors above
the 100 microasec level. Known errors include limited SNR\, lack of phase
calibration\, troposphere mismodelling\, and terrestrial frame distortion
s. Actions are underway to reduce all of these errors. In particular\, a
collaboration between NASA and the ESA deep space antenna in Malargüe\,
Argentina is quickly reducing weaknesses in the southern hemisphere. By l
ooking at the best observed sources\, we probe the accuracy limits of curr
ent celestial frames in an effort to understand the advantages of each fra
me.\n\nhttps://events.saip.org.za/event/56/contributions/4633/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4633/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Progress on the United Nations Global Geospatial Information Manag
ement initiative on the Global Geodetic Reference Frame and the Norwegian
Mapping Authority's core station project at 79°\; North
DTSTART;VALUE=DATE-TIME:20160314T131000Z
DTEND;VALUE=DATE-TIME:20160314T132500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4634@events.saip.org.za
DESCRIPTION:Speakers: Per Erik Opseth (Norwegian Mapping Authority)\nFebru
ary 26th 2015 the United Nations General assembly adopted the resolution o
n the Global Geodetic Reference Frame (GGRF). Presently major effort under
a UN mandate is entered into developing a road map giving guidance to how
the GGRF shall become sustainable. This work will influence the geodetic
framework conditions in the years to come. As a contribution to global geo
desy\, Norway is building a core station at Ny-Ålesund\, Spitsbergen. Pre
sently the station buildings and fundaments are finished and waiting for t
he new twin VLBI telescopes to be installed.\n\nhttps://events.saip.org.za
/event/56/contributions/4634/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4634/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hard- and software tools for the education of Geodetic VLBI
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4635@events.saip.org.za
DESCRIPTION:Speakers: Thomas Hobiger (Chalmers / Onsala Space Observatory)
\nOnsala Space Observatory hosts two 2.3 m radio telescopes called SALSA (
"Such a lovely small antenna") which are utilised to bring front-line inte
ractive astronomy to the classroom. Until now SALSA has been used for astr
onomical educational purposes solely\, in particular demonstrating the con
cept of single dish measurements. However\, it is possible to combine both
SALSAs to an interferometer by making use of hardware which has been deve
loped for software-defined radio. In doing so\, one can utilise the SALSA
antenna pair as a student demonstrator for geodetic Very Long Baseline Int
erferometry. We will discuss the COTS hardware components that are necessa
ry to turn the SALSA installation into an interferometer. Moreover\, we wi
ll show how a simple correlator has been used to detect fringes and provid
e single-band delays. Such delays were then processed with our analysis so
ftware c5++. We are going to discuss how it is possible to mimic the compl
ete processing chain of geodetic VLBI and how this can be used for trainin
g of students and other interested parties.\n\nhttps://events.saip.org.za/
event/56/contributions/4635/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4635/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Transition to the vgosDb data format.
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4636@events.saip.org.za
DESCRIPTION:Speakers: John Gipson (NVI Inc/GSFC NASA)\nThe IVS Working Gro
up 4 developed the new format to store and exchange data obtained from geo
detic VLBI observations. The new data format\, vgosDb\, will replace exist
ing Mk4 databases this year. At the GSFC NASA we developed software that w
ill implement vgosDb format and will be used routinely to convert correlat
or output to the new data storage format. On this poster we present the vg
osDb capable utilities that will replace the legacy software and our plans
for switching to vgosDb format in the routine VLBI data analysis.\n\nhttp
s://events.saip.org.za/event/56/contributions/4636/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4636/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Estimating the Celestial Reference Frame via Intra-Technique Combi
nation
DTSTART;VALUE=DATE-TIME:20160317T073000Z
DTEND;VALUE=DATE-TIME:20160317T074500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4637@events.saip.org.za
DESCRIPTION:Speakers: Andreas Iddink (Institute of Geodesy and Geoinformat
ion\, University of Bonn)\nOne of the primary goals of VLBI is the determi
nation of a CRF. Currently the third realization of the internationally ad
opted CRF\, the ICRF3\, is under preparation. In this process\, various op
timizations are planned to realize a CRF which does not only benefit from
the increased number of observations. For instance\, various campaigns hav
e been performed to sample the southern hemisphere with a better density.
Furthermore\, the VLBI Calibrator Surveys have been redone. Further optimi
zations of the ICRF3 with respect to the prior versions will be obtained o
n the analysis side. The new ICRF will benefit also from an intra-techniqu
e combination as it is also done for the TRF. Following IUGG Resolution No
. 3 (2011) this approach can then easily be extended to a consistent estim
ation of CRF\, TRF and the EOPs\, based on the observations of different g
eodetic space techniques.\n\nHere\, we aim at estimating an optimized CRF
by means of an intra-technique combination. The solutions are based on the
input to the official combined product of the International VLBI Service
for Geodesy and Astrometry (IVS)\, also providing the radio source paramet
ers. We discuss the differences in the setup between the classical TRF-EOP
combination and an extended CRF-TRF-EOP combination. Furthermore\, we inv
estigate the differences between the combined CRF and the CRFs for the ind
ividual ACs. Finally\, the impact on the TRF and the EOPs are analyzed to
demonstrate the benefits of our enhanced combination procedure.\n\nhttps:/
/events.saip.org.za/event/56/contributions/4637/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4637/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Implementation of the VGOS Trials
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4638@events.saip.org.za
DESCRIPTION:Speakers: Dirk Behrend (NVI\, Inc.)\nIn February 2014\, the VG
OS Project Executive Group (VPEG) presented the\nso-called VGOS Observing
Plan\, which outlined possible steps on how to go from initial VGOS broadb
and tests to intermediate observing scenarios to the fully operational VGO
S system. The document introduced VGOS trial campaigns as the initial mean
s to accustom the VGOS stations as well as the subsequent component types
to the VGOS processing load: scheduling\, data taking\, data transport\, c
orrelation\, and analysis. Three different trial campaigns of 6-8 weeks ea
ch were envisioned. The Coordinating Center in conjunction with the Observ
ing Program Committee (OPC) was tasked with their implementation. In this
presentation we will discuss the progress made on implementing the trial c
ampaigns.\n\nhttps://events.saip.org.za/event/56/contributions/4638/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4638/
END:VEVENT
BEGIN:VEVENT
SUMMARY:New DiFX sofware correlator cluster at Bonn
DTSTART;VALUE=DATE-TIME:20160316T073000Z
DTEND;VALUE=DATE-TIME:20160316T074500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4639@events.saip.org.za
DESCRIPTION:Speakers: Arno Mueskens (IGG Uni Bonn)\nWe present the status
of the Bonn Correlator Center (2015/2016)\nfor astronomical and geodetic c
orrelation. The correlator\ncenter is being operated jointly by the Max Pl
anck Institute for Radio\nAstronomy (MPIfR) in Bonn\, the Federal Agency f
or\nCartography and Geodesy (BKG) in Frankfurt with support from the\nInst
itute of Geodesy and Geoinformation (IGG) in Bonn for more than 20\nyears.
\nWe will give a brief summary of the first experience with correlating on
our new DiFX correlator cluster\, which was planned to be compatible with
the VGSO requirements. \nWe will also report on new features implemented
for instance to handle Mark 6 recordings and some benchmarking of the corr
elation of VGOS observations\, and on planned further software improvement
s.\n\nhttps://events.saip.org.za/event/56/contributions/4639/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4639/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The IVS Contribution to JTRF2014
DTSTART;VALUE=DATE-TIME:20160316T120000Z
DTEND;VALUE=DATE-TIME:20160316T121500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4640@events.saip.org.za
DESCRIPTION:Speakers: Richard Gross (Jet Propulsion Laboratory)\nKALREF\,
JPL's KALman filter and smoother for REference Frames\, has been used to p
roduce JTRF2014\, a combined terrestrial reference frame determined from t
he input SINEX files submitted by the IVS\, IGS\, ILRS\, and IDS for ITRF2
014. Using a Kalman filter and smoother allows the reference frame to be d
etermined sequentially as a time series. Incorporating process noise\, det
ermined from geophysical fluid loading models\, allows the observed statio
n positions to be smoothed between discontinuities caused by earthquakes a
nd equipment changes. Non-linear and non-seasonal changes in station posit
ions\, such as postseismic displacements\, are automatically included in t
he smoothed time series. The creation of JTRF2014 will be discussed with a
n emphasis on the contribution that the VLBI observations made to it.\n\nh
ttps://events.saip.org.za/event/56/contributions/4640/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4640/
END:VEVENT
BEGIN:VEVENT
SUMMARY:First 2 Gbps observations between KVAZAR VGOS antennas and Yebes R
AEGE antenna
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4641@events.saip.org.za
DESCRIPTION:Speakers: Pablo de Vicente (Observatorio de Yebes (IGN))\nA se
ries of joint test observations using three 13-m VGOS antennas were carrie
d on between September and November\, 2015. These were include 256 Mbps ex
periments as well as first 2 Gbps observations. Different working setups o
f DBBC were tested at Yebes\, data recorded\, and transferred to IAA Corre
lator Center. Combined correlation of mixed bandwidth data from KVAZAR ant
ennas and Yebes were performed with DiFX 2.4.1 and some results were obtai
ned.\n\nhttps://events.saip.org.za/event/56/contributions/4641/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4641/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Selecting sources that define a stable celestial reference frame w
ith the Allan variance
DTSTART;VALUE=DATE-TIME:20160317T074500Z
DTEND;VALUE=DATE-TIME:20160317T080000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4642@events.saip.org.za
DESCRIPTION:Speakers: Karine Le Bail (NVI\, Inc.)\nICRF2 was adopted by th
e IAU in 2009 and was based on the position of 3414 radio sources determin
ed by VLBI. Discussions on the next realization of the ICRF (ICRF3) have b
een underway within the IAU and IVS since 2012. VLBI has made significant
advances since ICRF2.\nFrom the latest GSFC solution\, we extract a set of
sources that defines a stable celestial reference frame\, as shown by M.
Feissel-Vernier 2003 (A&A) using tools such as the Allan variance and the
drift of the position time series. This method also allows us to highlight
a set of the least "stable" sources that may need special handling.\n\nht
tps://events.saip.org.za/event/56/contributions/4642/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4642/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Prototyping automation and dynamic observing with the AuScope arra
y
DTSTART;VALUE=DATE-TIME:20160315T074500Z
DTEND;VALUE=DATE-TIME:20160315T080000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4643@events.saip.org.za
DESCRIPTION:Speakers: Jim Lovell (University of Tasmania)\nThe continuous
observing mode envisioned for the new array of VGOS stations would benefit
greatly from a high level of automation\, from scheduling through to anal
ysis. The centrally-operated AuScope VLBI array of three 12m antennas in A
ustralia is serving as a testbed for these automation techniques. Here we
describe the challenges we are addressing\, how we are using simulations t
o undertand where the most benificial improvements can be obtained (in dyn
amic scheduling for example) and present the progress we have already made
.\n\nhttps://events.saip.org.za/event/56/contributions/4643/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4643/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Connected-element interferometry and error analysis of Beidou GEO
navigation satellites
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4644@events.saip.org.za
DESCRIPTION:Speakers: Fengchun Shu (Shanghai Astronomical Observatory)\nUs
ing the same frequency standard\, a high-precision phase delay can be obta
ined in a connected element interferometry (CEI) system. Beidou GEO naviga
tion satellite C02 is tracked from a CEI observations\, where the CEI of t
he two stations at hangtiancheng and shahe linked by a phase stabilization
system is built by Beijing Aerospace Control Center (BACC). And Beidou GE
O navigation satellite C03 is applied as calibration to conduct a differen
tial measurement. After introducing group-delay-aided phase delay\, the me
asure noise of the interferometry delay is about 9.4ps (root mean square o
f the linear fitting residuals in each 300 seconds). Following a different
ial observation as "2 hours calibration-13 hours tracking -2 hours calibra
tion"\, the accuracy of the interferometry delay for C02 is better than 0.
4ns. Results show that using a GEO satellite with high-accuracy ephemeris
as the calibration\, a high-accuracy interferometry can be achieved for th
e target satellite using small aperture antennas.\n\nhttps://events.saip.o
rg.za/event/56/contributions/4644/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4644/
END:VEVENT
BEGIN:VEVENT
SUMMARY:First Local Ties from Data of the Wettzell Triple Radiotelescope A
rray
DTSTART;VALUE=DATE-TIME:20160315T092500Z
DTEND;VALUE=DATE-TIME:20160315T094000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4645@events.saip.org.za
DESCRIPTION:Speakers: Torben Schüler (Geodetic Observatory Wettzell - BKG
)\nThe Geodetic Observatory Wettzell features a 20 m radiotelescope (RTW)
as well as two new 13.2 m TWIN telescopes. Whilst RTW performs routine ope
rations since 1984\, the first of the TWIN telescopes\, TTW1\, has entered
its productive phase in mid 2014\, and TTW2 has just been equipped with a
n Elevenfeed broadband receiving system.\n\nThe triple telescope array at
Wettzell establishes a geodetic very short baseline interferometry network
. Local correlation yields group delay observations for baseline estimatio
n from VLBI data alone without any immediate augmentation by terrestrial m
easurements. Apart from relative positioning of the telescopes\, these are
versatile capabilities for an end-to-end quality control of the VLBI data
.\n\nResults from local VLBI data analysis will be portrayed in this contr
ibution and compared to the latest local ties from precision terrestrial s
urveying. Moreover\, monitoring results of the TTW2 reference point will b
e presented and an initial concept for continuous surveillance of the TWIN
reference points is discussed.\n\nhttps://events.saip.org.za/event/56/con
tributions/4645/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4645/
END:VEVENT
BEGIN:VEVENT
SUMMARY:On the impact of different mapping functions on geodetic and tropo
spheric products from VLBI data analysis
DTSTART;VALUE=DATE-TIME:20160317T103000Z
DTEND;VALUE=DATE-TIME:20160317T104500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4646@events.saip.org.za
DESCRIPTION:Speakers: Kyriakos Balidakis (Technische Universität Berlin\,
Institute of Geodesy and Geoinformation Science\, Berlin\, Germany)\nDue
to the highly volatile character of the neutral atmosphere\, the modeling
of the related propagation delay is challenging. This poses the most promi
nent limitation in the precision and accuracy of the parameters estimated
in very long baseline interferometry (VLBI) data analysis. Hence\, it is o
f paramount importance that all parameters involved in the process to desc
ribe the atmosphere induced delay effects such as mapping functions or gra
dients are rigorously accounted for.\nIn this work\, we assess the impact
of different mapping functions (MFs) in the analysis of the 24-hour VLBI s
essions from 2002 onwards. Besides the original Vienna mapping functions (
VMF1)\, which are based on data from ECMWF operational analysis\, we apply
MFs based on this concept but utilizing data from ray tracing in CMC's GD
PS (UNB-VMF1). In addition to these we test the concept of advanced mappin
g using ECMWF's ERA-Interim reanalysis based on rigorous ray-tracing appro
ach. For the parameter estimation we use the VieVS@GFZ software applying t
he classical Gauß-Markov model. \nThe purpose of this study is twofold. W
e investigate the effect of these analysis options on the baseline length
repeatability as well as on the time series of station\, source coordinate
s and Earth orientation parameters. As far as the tropospheric products ar
e concerned\, estimated zenith wet delays and linear horizontal gradients
are compared with the ray traced ones from the aforementioned models.\n\nh
ttps://events.saip.org.za/event/56/contributions/4646/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4646/
END:VEVENT
BEGIN:VEVENT
SUMMARY:INVITED TALK: An Overview of the Japanese GALA-V Wideband V
LBI System
DTSTART;VALUE=DATE-TIME:20160314T074000Z
DTEND;VALUE=DATE-TIME:20160314T080500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4647@events.saip.org.za
DESCRIPTION:Speakers: Mamoru Sekido (National Institute of Information and
Communications Technology)\nWe are developing a new broadband VLBI system
\, named GALA-V with aim of frequency comparison between atomic time stand
ards over intercontinental distances. The development of broadband GALA-V
system is coordinated to be as compatible as possible with the VGOS system
. Kashima 34m antenna that had modified Cassegrain optics was enabled to c
arry out broadband observation with originally developed two types of prot
otype broadband feeds named IGUANA-H and NINJA. Two ways of data acquisiti
on modes\; broad channel mode and narrow channel mode\, are employed in th
e project. Narrow channel mode acquires multiple channels of 32MHz bandwid
th\, and this mode is compatible with the observation mode developed by MI
T Haystack as the ‘NASA proof of Concept’ (PoC) system. Broad channel
mode acquires four channels of 1 GHz bandwidth signal. RF Direct sampling
technique is applied in this mode as a new approach for broadband observat
ion by using high speed sampler K6/GALAS. This technique has several advan
tages in precision delay derivation by broadband bandwidth synthesis. \nI
shioka 13m VGOS station has constructed by GSI in Japan\, and the first br
oadband observation over 8 GHz bandwidth was successfully performed in ear
ly 2015 on Kashima 34m - Ishioka 13m baseline. We have achieved super broa
dband bandwidth synthesis over 8GHz bandwidth for the first time in the wo
rld. The theoretical delay precision has reached about 30 femto seconds in
this experiment. This presentation will report about recent progress of t
he broadband GALA-V developments.\n\nhttps://events.saip.org.za/event/56/c
ontributions/4647/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4647/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Current Status of Ishioka VGOS antenna
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4648@events.saip.org.za
DESCRIPTION:Speakers: Ryoji Kawabata (Geospatial Information Authority of
Japan)\nThe Geospatial Information Authority of Japan (GSI) is constructin
g a new VGOS station in Ishioka. The construction of the 13-m antenna has
been finished\, and a new operation building will be completed by February
2016. Ishioka 13-m antenna is observing legacy S/X-band VLBI observation
with Tsukuba 32-m antenna by using tri-band feed system. We have also carr
ied out some broadband experiments collaborating with the National Institu
te of Information and Communications Technology (NICT). The paper reports
current situation of Ishioka VGOS antenna including recent geodetic result
of VLBI observation.\n\nhttps://events.saip.org.za/event/56/contributions
/4648/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4648/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Activities of Sejong station and toward the GGOS
DTSTART;VALUE=DATE-TIME:20160315T094000Z
DTEND;VALUE=DATE-TIME:20160315T095500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4649@events.saip.org.za
DESCRIPTION:Speakers: Sang Oh YI (NGII(National Geographic Information Ins
titutue))\nThe Sejong station is a part of SGOC(Space Geodetic Observation
Center) which belongs to NGII(National Geographic Information Institute).
We will present conventional S/X system issues that we need to improve\,
establishment of sever cluster for S/W correlation(Storage about 100TB)\,
local tying results for collocation\, installation of the ARGO(Mobile SLR
system\, 40cm diameter) which developed by KASI(Korea Astronomy & Space Sc
ience Institute) at the SGOC site\, current progress of construction KVNG(
Korea VLBI Network for Geodesy) and development of wide-band feed horn for
VGOS.\n\nhttps://events.saip.org.za/event/56/contributions/4649/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4649/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Status and first results from the VGOS-compatible antenna Ws with
an Elevenfeed at Wettzell
DTSTART;VALUE=DATE-TIME:20160314T103000Z
DTEND;VALUE=DATE-TIME:20160314T104500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4650@events.saip.org.za
DESCRIPTION:Speakers: Gerhard Kronschnabl (Geodetic Observatory Wettzell)\
nThe VGOS antenna Ws at Wettzell is equipped with an Elevenfeed\, having a
continuous frequency range from 2 GHz - 14 GHz. The receiving system with
eight parallel intermediate frequency channels enables the use of four ba
nds at different polarizations. A DBBC in combination with a FILA10G and a
Mark6 System is used as backend. The presentation gives an overview about
the current status of the broadband development and the recording systems
installed at the Wettzell antenna Ws.\n\nhttps://events.saip.org.za/event
/56/contributions/4650/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4650/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Preparations for a new VGOS radio telescope at HartRAO
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4651@events.saip.org.za
DESCRIPTION:Speakers: Ludwig Combrinck (HartRAO)\nVery long baseline inter
ferometry (VLBI) is used in geodesy to determine a telescope’s position
relative to the galactic centre. A modern\, fast slewing radio telescope m
easuring approximately 13 metres in diameter have been chosen to be used i
n the VLBI Global Observing System (VGOS)\, which will help improve the ac
curacy across global baselines from around 1 cm down to 1 mm. In 2014 Hart
RAO started the process of obtaining the new radio telescope which will be
used within the VGOS network. Specifying the telescope requirements\, Rad
io Frequency Interference (RFI) measurements\, core drilling and logging\,
and an Environmental Impact Assessment (EIA) are part of the prerequisite
actions that need to take place before construction can commence.\n\nhttp
s://events.saip.org.za/event/56/contributions/4651/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4651/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Current Status of Shanghai VLBI Correlator
DTSTART;VALUE=DATE-TIME:20160316T080000Z
DTEND;VALUE=DATE-TIME:20160316T081500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4652@events.saip.org.za
DESCRIPTION:Speakers: Wu Jiang (SHAO\,CAS)\nShanghai Astronomical Observat
ory has upgraded its DiFX cluster to a 420 cpu cores and a 432 TB storage
system at the end of 2014. An international network connection for the raw
data transfer has also been established. The routine operations for IVS s
essions including CRF\, AOV\, and APSG series began from the ealy 2015.Som
e X/Ka fringe search experiments were conducted with Tianma 65-m radio tel
escope in order to check its performance. In addition to the IVS observati
ons\, the correlator is also dedicated to astrophysical and astrometric ob
servations with Chinese VLBI network\, the east Asian VLBI network and som
e international joint VLBI observations. Meanwhile\, comparisons to the do
mestic software correlator and the SFXC correlator are to be made with DiF
X. Shanghai correlator is also planning a more powerful platform for the f
uture correlation tasks.\n\nhttps://events.saip.org.za/event/56/contributi
ons/4652/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4652/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Update on the Spanish-Portuguese RAEGE project
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4653@events.saip.org.za
DESCRIPTION:Speakers: Pablo de Vicente (Observatorio de Yebes (IGN))\nAn u
pdate of the deployment and activities at the Spanish/Portuguese RAEGE pro
ject (“Atlantic Network of Geodynamical and Space Stations”) is presen
ted. Regular observations with Yebes radio telescope are ongoing. Commissi
oning of the radio telescope at Santa Maria is advanced\, and site works f
or a new station in Tenerife (Canary Islands) have started. Technological
developments on receivers for VGOS are progressing at Yebes laboratories\,
as well as works on local-ties.\n\nhttps://events.saip.org.za/event/56/co
ntributions/4653/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4653/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The progress of Seshan VGOS station construction
DTSTART;VALUE=DATE-TIME:20160314T093000Z
DTEND;VALUE=DATE-TIME:20160314T094500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4654@events.saip.org.za
DESCRIPTION:Speakers: Guangli Wang (Shanghai Astronomical Observatory)\nTh
e Seshan VGOS station is now in building. It is a very-fast-slewing 13.2m
antenna\, with QRFH wideband feed\, and a realtime 3D measurement system o
f reference point variation is planing to install. And it locates in the y
ard of Tianma 65m radio telescope. Its recent progress will be introduced
in this report.\n\nhttps://events.saip.org.za/event/56/contributions/4654/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4654/
END:VEVENT
BEGIN:VEVENT
SUMMARY:VLBI Delay Reduced from S/C Observation and its Calibration in Cha
ng’E Mission
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4657@events.saip.org.za
DESCRIPTION:Speakers: Guangli Wang (Shanghai Astronomical Observatory)\nVL
BI technique was used in China’s Lunar Exploration Project Since the Cha
ng’E-1 launched in the year of 2007\, after then VLBI was played an impo
rtant role in the series of Chang’E missions\, CE-2\, CE-3 and CE-5T1\,
and will be continued in the future space mission. The observation network
consists of Shanghai 25m&65m\, Beijing 50m\, Kunming 40m and Urumqi 25m r
adio telescopes. Up to now it still works in the traditional astronomy-com
patible S/X station systems \, both quasar and S/C are observed in the sa
me Frequency setup. In CE-1 & CE-2 the quasar and S/C switching rules are
15min quasar and 45min S/C\, in CE-3 and thereafter are <5min switching.\n
\nhttps://events.saip.org.za/event/56/contributions/4657/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4657/
END:VEVENT
BEGIN:VEVENT
SUMMARY:On the impact of inhomogeneities in meteorological data on VLBI da
ta analysis
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4658@events.saip.org.za
DESCRIPTION:Speakers: Kyriakos Balidakis (Technische Universität Berlin\,
Institute of Geodesy and Geoinformation Science\, Berlin\, Germany)\nIn t
his study\, the issue of the quality of meteorological data employed for V
LBI data analysis is addressed. Traditionally\, ambient barometric pressur
e and temperature values are used to model the hydrostatic component of th
e neutral atmospheric propagation delay and the thermal deformation of ant
ennas\, in VLBI data analysis. Unlike the other microwave-based space geod
etic techniques currently contributing to the TRF\, where the necessary me
teorological data are customarily acquired by either empirical or numerica
l weather models\, VLBI analysis has the advantage that the aforementioned
nuisance effects can be potentially eliminated more effective employing i
n situ meteorological data. Nevertheless\, there are cases where erroneous
meteorological records yield unacceptable products which have a dubious t
raceability. For instance\, if the recorded pressure series at a certain s
ite has a significant positive bias with respect to the actual one\, negat
ive zenith wet delays will indicate a serious problem. Should the bias be
anything but like this\, its detection will be challenging and it will con
taminate the geodetic products of the site and potentially at other sites
participating in the same session. In the long term\, such biases will aff
ect the scale of the estimated TRF.\nWe establishe a service for the onlin
e detection and correction of inhomogeneities in recorded meteorological d
ata at the VLBI sites. Employing the homogenized data set\, the “IVS Rap
id Tropospheric Combination Center” is re-launched providing zenith tota
l and wet delays\, as well as linear horizontal gradients.\n\nhttps://even
ts.saip.org.za/event/56/contributions/4658/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4658/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A Technical Overview of the EVN
DTSTART;VALUE=DATE-TIME:20160316T071500Z
DTEND;VALUE=DATE-TIME:20160316T073000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4659@events.saip.org.za
DESCRIPTION:Speakers: Pablo de Vicente (Observatorio de Yebes (IGN))\nAs c
hair of the Technical and Operations Group (TOG) of the European VLBI Netw
ork (EVN) I would like to present an overview of the technical aspects of
the EVN. I will explain which institutes and telescopes constitute the EVN
\, and their main characteristics and observation frequencies. The schedul
ing process together with fringe tests\, network monitor experiments\, sta
ndard observations\, e-VLBI observations and target of opportunity observa
tions will be described. The EVN signed a MoU with JIVE and as result acti
vities from both sides are deeply interleaved. I will present some of thes
e activities with relevant impact in the EVN. I will also describe the cal
ibration control process. Finally technical developments in the last year\
, including 2 Gbps recording in DDC mode\, 2 Gbps recording in VDIF format
supported by the FS for Mark5C\, Mark6 and Flexbuff and the works to get
PFB mode will also be presented together with the tests performed. These d
evelopments are the result of collaboration works from different parties i
n the EVN and also NVI Inc with with which the EVN signed a contract.\n\nh
ttps://events.saip.org.za/event/56/contributions/4659/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4659/
END:VEVENT
BEGIN:VEVENT
SUMMARY:INVITED POSTER: APOD mission status and observe APOD by VLB
I
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4660@events.saip.org.za
DESCRIPTION:Speakers: Guangli Wang (Shanghai Astronomical Observatory)\nOn
Sept. 20\, 2015\, the Chinese CZ-6 test rocket was launched successfully
from TaiYuan Satellite Launch Center\, and 20 satellites was sent simultan
eously into a circular\, near-polar and 520 Km altitude orbit. Among thes
e 20 satellites\, four CubSats\, named with APOD (Atmospheric density dete
ction and Precise Orbit Determination)\, are projected for atmospheric den
sity in-situ detection and derivation via precise orbit. The APOD satellit
es\, manufactured by DFH Co.\, carries a number of instruments including d
ensity detector\, dual-frequency GNSS (GPS/BD) receiver\, SLR reflector an
d S/X band VLBI beacon. The mission aims to detect atmospheric density bel
ow 520 Km. The ground segment is run by BACC for payload operation as well
as science data receiving\, processing\, archiving and distribution. Curr
ently\, one of the APOD satellites and payload validation had finished\, a
nd the preliminary resultsare presented as follows. The precision of orbit
determination is about 10cm by both overlap method and by compared with S
LR observation\, and the derived atmospheric density from this precise orb
it determination matches well with in-situ detection. \n\nSince three spac
e geodetic techniques (i.e. GNSS\, SLR\, and VLBI) are co-located on APOD
satellite\, the observations can be used for combination and validation in
order to detect the systematic differences. Furthermore the observations
of APOD satellite by VLBI radio telescope scan be used in an ideal fashion
to link the dynamical reference frames of the satellite with terrestrial
and\, most importantly\, to the celestial reference frame as defined by th
e positions of quasars. From a VLBI observational point of view\, APOD sat
ellites rather challenging since mutual visibility depends on the altitude
of APOD satellite and the separation of the radio telescopes. And the APO
D satellite travel through the field of view very fast. The possibility of
observing APOD satellite by IVS VLBI radio telescopes will be analyzed in
the presentation\, considering continental-size VLBI observing networks a
nd the small telescopes with sufficient speed.\n\nhttps://events.saip.org.
za/event/56/contributions/4660/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4660/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The effects of quasar variability on astrometry
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4661@events.saip.org.za
DESCRIPTION:Speakers: Shabala Stanislav (University of Tasmania)\nRadio so
urces observed in global IVS sessions are mostly flat-spectrum radio-loud
quasars. While some quasars appear almost point like\, many have extended
jet components in addition to compact cores. The structure of these jets o
ften varies on timescales of months to years as the black hole at the cent
re of the quasar accretes new material and ejects components of radio-emit
ting plasma. These components expand adiabatically as they move away from
the compact core\, and eventually disappear. In this way\, the structure a
nd flux density of quasars are related.\n\nWe present an analysis of nine
variable quasars frequently observed in global geodetic VLBI programs. We
find a clear anti-correlation between source flux density and structure in
dex\, in the sense that the brightest sources are also the most compact. T
his anti-correlation is stronger on the rising side of the flare\, consist
ent with astrophysical expectations. Consistent with previous findings\, w
e show that bright\, compact quasars also have more repeatable astrometric
positions. We suggest that flux density time series may be a useful addit
ional piece of information used in selecting quasars for geodetic VLBI obs
ervations.\n\nhttps://events.saip.org.za/event/56/contributions/4661/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4661/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Italian VLBI network: first results and future perspectives
DTSTART;VALUE=DATE-TIME:20160316T070000Z
DTEND;VALUE=DATE-TIME:20160316T071500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4669@events.saip.org.za
DESCRIPTION:Speakers: Matteo Stagni (IRA - INAF)\nA first 24-h Italian VLB
I geodetic experiment\, involving the Medicina\, Noto and Matera antennas\
, shaped as an IVS standard EUROPE\, was successfully performed. Starting
from the correlator output\, a geodetic database was created and a typical
solution of a small network was achieved\, here presented. From this prom
ising result\, we have planned new observations in 2016\, involving the th
ree Italian geodetic antennas\, that should be the beginning of a possible
routine activity\, creating a data set that can be combined with GNSS obs
ervations to contribute to the National Geodetic Reference Datum. Particul
ar care should be taken in the scheduling of the new experiments in order
to optimize the number of the usable observations. These observations can
be used to study and plan future experiments in which the time and frequen
cy standards can be given by an optical fiber link\, so having a common cl
ock at different VLBI stations.\n\nhttps://events.saip.org.za/event/56/con
tributions/4669/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4669/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Observing with sibling and twin telescopes
DTSTART;VALUE=DATE-TIME:20160315T073000Z
DTEND;VALUE=DATE-TIME:20160315T074500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4662@events.saip.org.za
DESCRIPTION:Speakers: Lucia Plank (University of Tasmania)\nWith the trans
ition to VGOS\, co-located radio telescopes will be common at many sites.
This can be as a sibling telescope\, when a VGOS antenna is built next to
a legacy one or as the concept of a twin telescope\, with two identical VG
OS antennas. \nThe co-location of two antennas offers new possibilities in
both operation and analysis. The immediate question for observing with a
sibling/twin telescope is the applied observing strategy and its realisati
on in the scheduling software.\nIn this contribution we report about our e
fforts implementing new scheduling modes for sibling and twin telescopes i
n the Vienna VLBI Software. On the example of the sibling telescope in Hob
art\, several types of sessions will be discussed: scheduling redundant ob
servations observing in identical scans\, improved troposphere solution th
rough observations in different directions\, improved antenna sensitivity
through adding the legacy antenna for observations to weak sources\, or se
ssions dedicated to determine the local baseline.\nResults from sibling ex
periments\, applying new analysis strategies combining common parameters\,
will further demonstrate the potential of twin telescopes for VGOS.\n\nht
tps://events.saip.org.za/event/56/contributions/4662/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4662/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Improvement of the IVS-INT01 Sessions
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4663@events.saip.org.za
DESCRIPTION:Speakers: John Gipson (NVI Inc/GSFC NASA)\nAn on-going goal of
the GSFC Analysis Center is the improvement of the UT1 formal error obtai
ned from the IVS-INT01 sessions\, as well as the improvement of related me
trics\, such as robustness against atmospheric turbulence. Improvement can
be achieved by improving the scheduling and/or the analysis of these sess
ions. Here we report on our latest efforts to improve the performance of
the IVS-INT01 sessions.\n\nhttps://events.saip.org.za/event/56/contributio
ns/4663/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4663/
END:VEVENT
BEGIN:VEVENT
SUMMARY:From CONT to VGOS: The Evolution of the CONT Campaigns
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4664@events.saip.org.za
DESCRIPTION:Speakers: Cynthia Thomas (NVI\, Inc.)\nContinuous VLBI Campaig
ns (CONT) started in 1994 with the goal of demonstrating state of the art
VLBI over a continuous period of time. The first CONT was followed by camp
aigns in 1995 and 1996. After a six year hiatus\, CONT campaigns were orga
nized approximately every three years from 2002 through 2014. In this pres
entation we primarily focus on the cornerstones of each CONT campaign. Spe
cifically\, we review the developments in networks\, scheduling techniques
\, recording media\, correlation\, and other resources used. A timeline of
the history of the CONTs and the goals for future campaigns will be prese
nted. The CONTs used a significant amount of IVS resources to produce a la
rge volume of high quality data and demonstrated the advantages of continu
ous observing which will soon be realized with VGOS.\n\nhttps://events.sai
p.org.za/event/56/contributions/4664/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4664/
END:VEVENT
BEGIN:VEVENT
SUMMARY:On your Marks ... Flex\, Buff and VGOS\, partly even in real-time
DTSTART;VALUE=DATE-TIME:20160314T123000Z
DTEND;VALUE=DATE-TIME:20160314T124500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4665@events.saip.org.za
DESCRIPTION:Speakers: harro verkouter (Joint Institute for VLBI ERIC\, Dwi
ngeloo)\nModern\, VGOS and general purpose radio-astronomical digital back
ends (DBEs)\, will produce enormous amounts of data\, posing some challen
ges for the recorders. Fortunately\, the availability of ever faster digit
al hardware has also meant that capturing these large data streams on - re
latively speaking - general purpose hardware has become quite feasible.\n\
nCurrently there are two models of ethernet packet recorders in use: MIT H
aystack's Mark6 and the FlexBuff\, developed in the European VLBI Network
(EVN). As the hardware has become more and more commercial-off-the-shelf (
COTS) so has grown the importance of software support\; in fact\, these ne
wer recorders are full software recorders.\n\nAs such the usability and pe
rformance of such a recorder is completely defined by the functionality of
the software running on it. In this talk I would like to introduce the ca
pabilities of EVN's software jive5ab on this class of recorders and what e
xtra benefits it may have for dealing with recorded ethernet data.\n\nBesi
des these mundane recording aspects\, I would like to present\, on behalf
of Stuart Weston (Warkworth\, New Zealand) and Simone Bernhart (IGG Bonn)\
, an application of the features of the jive5ab recording software for rea
l-time recording of IVS R1 sessions.\n\nIn this test the scans were record
ed on Warkworth's Mark5B+ but also\, in parallel and in real-time\, at the
cluster in Bonn. This has proven to work and provides a measurable increa
se in turn-around time for correlation with a minimum of hassle if more st
ations [w/c]ould do this.\n\nhttps://events.saip.org.za/event/56/contribut
ions/4665/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4665/
END:VEVENT
BEGIN:VEVENT
SUMMARY:IVS Retreat 2015
DTSTART;VALUE=DATE-TIME:20160314T080500Z
DTEND;VALUE=DATE-TIME:20160314T082000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4666@events.saip.org.za
DESCRIPTION:Speakers: Axel Nothnagel (Institute of Geodesy and Geoinformat
ion\, University of Bonn)\nOn October 7 and 8\, 2015\, the IVS Directing B
oard held an IVS Retreat at the Dominion Radio Astrophysical Observatory\,
Penticton\, BC\, Canada\, to discuss current implications and future chal
lenges of the IVS’s existence and operations. In order to benefit from o
utside views\, six external advisors had been invited as well. The group s
pent two days discussing correlation\, product lines\, institutional relat
ions\, and operations details with concepts for the future. Critical items
included the aging of the experienced workforce of the IVS\, the preparat
ion of the correlators for the large increase in data throughput for VGOS\
, an emphasis on the service aspect of the IVS\, and the need for increase
d public relations work\, among other items. In this presentation\, the ch
air of the IVS will inform the participants about the retreat and its cons
equences.\n\nhttps://events.saip.org.za/event/56/contributions/4666/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4666/
END:VEVENT
BEGIN:VEVENT
SUMMARY:BRAND EVN
DTSTART;VALUE=DATE-TIME:20160314T082000Z
DTEND;VALUE=DATE-TIME:20160314T083500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4667@events.saip.org.za
DESCRIPTION:Speakers: Gino Tuccari (INAF-IRA and MPI)\nMulti-band concurre
nt observation capability for the frequencies bands commonly\nused in EVN
greatly could improve the VLBI scientific opportunities\, even enabling im
portant simplification in the radiotelescope operations.\nThe project for
a 1.5 - 15.5 GHz fully digital receiver is presented with the\npossible so
lutions for a smooth introduction in the different from each other\nEVN ra
diotelescopes.\n\nhttps://events.saip.org.za/event/56/contributions/4667/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4667/
END:VEVENT
BEGIN:VEVENT
SUMMARY:INVITED TALK: Status of the ICRF3 and Gaia activities
DTSTART;VALUE=DATE-TIME:20160316T130000Z
DTEND;VALUE=DATE-TIME:20160316T132500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4668@events.saip.org.za
DESCRIPTION:Speakers: Patrick Charlot (Laboratoire d'Astrophysique de Bord
eaux)\nThe ICRF3\, the next realization of the International Celestial Ref
erence Frame\, is going to be built within the next two years for approval
at the IAU 2018 General Assembly. This timescale is driven by the forthco
ming optical reference frame to be built by the Gaia mission and aligned a
t best with the ICRF3. The ICRF3 work is carried out by an IAU Working Gro
up set up in 2012. While the work so far was primarily focused on increasi
ng the pool of observations\, it must now concentrate on the analysis. The
Gaia mission is operational since September 2014\, observing 30-40 millio
n sources per day. It is performing largely nominally despite a few proble
ms which slightly degrade the accuracy. A first release of the Gaia data i
s planned for mid-2016 while a second release is expected by mid-2017.\n\n
https://events.saip.org.za/event/56/contributions/4668/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4668/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Application of Kalman filtering for the analysis of Intensive se
ssions
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4670@events.saip.org.za
DESCRIPTION:Speakers: Tobias Nilsson (GFZ German Research Centre for Geosc
iences)\nThe VLBI Intensive sessions are one-hour long\, usually single-ba
seline VLBI sessions performed every day in order to estimate UT1-UTC. Due
to the small number of observations in these sessions\, the latency betwe
en observation and results is relatively short\, normally a few days. Howe
ver\, the accuracy of the UT1-UTC estimates is significantly lower than ex
pected based on their formal errors. Although the reason for this is not c
ompletely understood\, it indicates that the results could get better if i
mproved modeling or estimation procedures are applied.\nIn this contributi
on\, we analyze the Intensive sessions with the newly developed Kalman fil
ter module of our software\, VieVS@GFZ\, and investigate whether results i
mprove compared to those obtained when applying the classical least square
s method for the data analysis. The accuracy is evaluated by comparing the
results for UT1-UTC as well as the tropospheric delays with the estimates
from 24-hour VLBI sessions on the same days as the Intensives. We study t
he impact of different stochastic modelling of the estimated parameters\,
e.g. of the tropospheric delays. Furthermore\, we test whether the results
could be improved by including tropospheric parameters estimated from GNS
S as additional observations in the Kalman filter.\n\nhttps://events.saip.
org.za/event/56/contributions/4670/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4670/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Images of VLBI calibrators from the BeSSeL survey
DTSTART;VALUE=DATE-TIME:20160317T094500Z
DTEND;VALUE=DATE-TIME:20160317T100000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4671@events.saip.org.za
DESCRIPTION:Speakers: Bo Zhang (Shanghai Astronomical Observatory)\nThe Be
SSeL Survey (Bar and Spiral Structure Legacy Survey) is a VLBA Key Science
project. The primary goal of the survey is to study the spiral structure
and kinematics of the Milky Way\, by measuring distances and proper motion
s to masers in regions of massive star formation across large portions of
the Milky Way. To measure the distances of masers via trigonometric parall
axes\, the relative positions between the masers and extragalactic VLBI ca
librators are determined with phase-referencing VLBI at different epochs s
panning at least 1 year. \n\nThe Masers are usually served as phase refere
nce since they are much stronger than the calibrators\, allowing several h
ours' integration times for the weak calibrators. In addition\, the calibr
ators are often observed though the whole observing program\, providing ex
cellent uv-coverage for imaging. From the BeSSeL survey\, there will be ab
out ~5000 high quality images of ~ 400 VLBI calibrators distributed near t
he Galactic plane. For each calibrator\, there are at least 4 images obtai
ned from different epochs spanning at least 1 year. In this talk\, I will
introduce the construction of the image database of these calibrators\, an
d discuss the potential application on VLBI astrometry using this image da
tabase.\n\nhttps://events.saip.org.za/event/56/contributions/4671/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4671/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Metsähovi Geodetic Fundamental Station in Finland - new VGOS site
\, plans\, and current status
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4672@events.saip.org.za
DESCRIPTION:Speakers: Nataliya Zubko (Finnish Geospatial Research Institut
e)\nThe Metsähovi Geodetic Fundamental Station is a key infrastructure of
the Finnish Geospatial Research Institute (FGI). It is a Global Geodetic
Observing System (GGOS) core site\, i.e.\, member of global network of geo
detic stations which is used in maintaining global terrestrial and celesti
al reference frames\, computing precise orbits of satellites\, and for geo
physical studies. Metsähovi is one of the few geodetic stations that has
all major geodetic observing instrumentations co-located. These include sa
tellite laser ranging (SLR)\, very long baseline interferometry (VLBI)\, g
lobal navigation satellite system (GNSS)\, superconducting and absolute gr
avimeters\, and the DORIS beacon. The station has been operational since 1
978\, it contributes several global services of the International Associat
ion of Geodesy (IAG)\, and due to its long existence it helps to retain su
stainability in the maintenance of global reference frames. \n\nIn the aut
umn 2015 FGI obtained financial support to build new VGOS compatible radio
telescope. This project is funded by Finnish Ministry of Agriculture and
Forestry and the National Land Survey. The site chosen for a new telescope
is within 100 m from other facilities of the Metsähovi geodetic station.
We aim for a 12-13 m telescope and expect to complete the procurement pro
cess during the first half of 2016. The plan is to be operational by the e
nd of 2018.\n\nhttps://events.saip.org.za/event/56/contributions/4672/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4672/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Defining Sources Selection and Celestial Reference Frame Stability
DTSTART;VALUE=DATE-TIME:20160317T080000Z
DTEND;VALUE=DATE-TIME:20160317T081500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4673@events.saip.org.za
DESCRIPTION:Speakers: César GATTANO (SYRTE - Observatoire de Paris)\nIn a
previous study\, we characterized radio sources observed by Very Long Bas
eline Interferometry by different criteria in both radio and optical domai
ns (see the abstract "VLBI sources in optical\nand radio"). On the basis o
f the data derived from this study\, we constructed several celestial refe
rence frames by choosing a set of defining sources and studied their stabi
lity by two ways\, statistically and temporally\, inspired by Lambert [201
3]. In parallel\, a re-analysis of the ICRF2 was made\, in the perspective
of ICRF3 (expected date : 2018)\, to estimate its current stability and i
f it has changed since 2009\, as it was the case for ICRF1 [ Gontier et al
. 2001\, Feissel-Vernier 2003\, Lambert et al. 2008\, Lambert & Gontier 20
09 ] . Finally\, an ambitious goal will be to develop by those works an au
tomatic tool that will regularly analyse new VLBI observation sessions and
will be able to alert the community on defining sources becoming potentia
lly unstable.\n\nhttps://events.saip.org.za/event/56/contributions/4673/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4673/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Plans and progress of the Vienna Correlator
DTSTART;VALUE=DATE-TIME:20160314T134500Z
DTEND;VALUE=DATE-TIME:20160314T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4674@events.saip.org.za
DESCRIPTION:Speakers: Johannes Boehm (Technische Universität Wien)\nThe V
LBI group at Technische Universität Wien (TU Wien) is going to run a VLBI
software correlator for scientific purposes. For that reason\, DiFX is in
stalled on the Vienna Scientific Cluster 3 (VSC-3) consisting of 2020 node
s\, each equipped with 2 processors (Intel Xeon E5-2650v2\, 2.6 GHz\, 8 co
res). Of course\, only a fraction of the total number of cores will be ava
ilable for VLBI correlation. The VSC-3 is connected to the scientific Geà
nt network with 10 Gbps\, thus providing a high bandwidth for downloading
data via e-transfer. In this presentation\, we provide information about t
he current status of that project and future plans.\n\nhttps://events.saip
.org.za/event/56/contributions/4674/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4674/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Simulations of near real-time EOP estimation from a future VGOS ne
twork
DTSTART;VALUE=DATE-TIME:20160316T095500Z
DTEND;VALUE=DATE-TIME:20160316T101000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4675@events.saip.org.za
DESCRIPTION:Speakers: Tobias Nilsson (GFZ German Research Centre for Geosc
iences)\nThe VLBI Global Observing System (VGOS) will present a number of
challenges for VLBI data analysis. For example\, there will be an increase
in the number of observations per day by a factor of 10-30 or even more.
Furthermore\, another goal of VGOS is to reduce the latency between observ
ation and availability of the results\, like the Earth Orientation Paramet
ers (EOP) to less than one day. Ideally\, the results should be available
in near real-time. Thus\, every part of the VLBI processing chain\, e.g. o
bservation\, data transfer\, correlation\, and data analysis\, needs to be
able to operate autonomously in real-time.\nTo meet the challenges that V
GOS will put on the data analysis part\, we have implemented a Kalman filt
er module in our software\, VieVS@GFZ\, which is able to analyze VLBI data
fully automated in near real-time. In this contribution\, we present this
module\, in particular the setup for real-time analysis\, and we test its
performance through simulation of a real-time estimation scenario from a
potential future 30 station VGOS network. We focus on the precision obtain
ed for the EOP\, which is the most interesting VLBI product in terms of ne
ar real-time availability. Furthermore\, we study how well the Kalman filt
er is able to autonomously cope with potential problems in the VLBI data\,
such as clock breaks.\n\nhttps://events.saip.org.za/event/56/contribution
s/4675/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4675/
END:VEVENT
BEGIN:VEVENT
SUMMARY:INVITED TALK: IVS contribution to the ITRF2014
DTSTART;VALUE=DATE-TIME:20160316T102500Z
DTEND;VALUE=DATE-TIME:20160316T105000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4676@events.saip.org.za
DESCRIPTION:Speakers: Sabine Bachmann (BKG)\nGenerating the contribution o
f the International VLBI Service for Geodesy and Astrometry (IVS) to the I
TRF2014 was the main task of the IVS Combination Center at the Federal Age
ncy for Cartography and Geodesy (BKG\, Germany) in 2015. Starting with the
ITRF2005\, the IVS contribution to the ITRF is an intra-technique combine
d solution using multiple individual contributions from different institut
ions.\nFor the ITRF2014 nine international institutions were used for a co
mbined solution. The data files contain 24h VLBI sessions from the late 19
70s until the end of 2014 in SINEX file format containing datum free norma
l equations with station coordinates and Earth orientation parameters (EOP
). All contributions have to meet the IVS standards for ITRF contribution
in order to guarantee a consistent combined solution.\nIn the course of th
e generation of the intra-technique combined solution\, station coordinate
time series for each station as well as a terrestrial reference frame bas
ed on the contributed VLBI data (VTRF) were generated and analyzed.\nThe d
ata analysis\, the combination procedure and results of the combined solut
ion for station coordinates and EOP will be presented.\n\nhttps://events.s
aip.org.za/event/56/contributions/4676/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4676/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The structure of the radio source 0642+449 detected from CONT14 ob
servations
DTSTART;VALUE=DATE-TIME:20160317T093000Z
DTEND;VALUE=DATE-TIME:20160317T094500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4677@events.saip.org.za
DESCRIPTION:Speakers: Minghui XU (Shanghai Astronomical Observatory)\nThe
CONT14 campaign features state-of-art VLBI data. Therein\, the radio sourc
e 0642+449 was observed with about one thousand observables each day durin
g the continuous observing period of fifteen days\, providing tens of thou
sands of closure delays\, the sum of the delays around a closed loop of ba
selines. The closure delay is independent of the instrumental and propagat
ion delays and provides valuable additional information about the source s
tructure. An example of the use of this new “observable” for the deter
mination of source structure is given for the radio source 0642+449. This
source\, as one of the defining sources in the second realization of the I
nternational Celestial Reference Frame (ICRF2)\, is found to have two poin
t-like components with separation of 425 milliarcseconds in right ascensio
n and 47 milliarcseconds in declination. The two components are almost equ
ally bright with the flux-density ratio up to 0.92. With the help of recen
t space VLBI observations at 1.6 GHz\, the morphology of 0642+449 could be
identified to some extent. The closure delays larger than 1 ns are found
to be caused by the source structure as well\, demonstrating the structure
effect of a source with this simple structure could reach up to tens of n
anoseconds\, at least one magnitude larger than expected. We anticipate ou
r study to be a starting point for more effective determination of the str
ucture effect in VLBI observations without the involvement of radio source
images.\n\nhttps://events.saip.org.za/event/56/contributions/4677/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4677/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Constraining Least Squares VLBI Solutions
DTSTART;VALUE=DATE-TIME:20160316T091000Z
DTEND;VALUE=DATE-TIME:20160316T092500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4678@events.saip.org.za
DESCRIPTION:Speakers: Thomas Artz (Institute of Geodesy and Geoinformation
\, University of Bonn)\nIn a traditional least squares adjustment of param
eters to the VLBI observation\, typically tropospheric as well as clock pa
rameters are determined in form of continuous piece-wise linear functions
(CPWLF) with a given temporal resolution. As the VLBI observations are not
equidistant\, and on the contrary\, exhibit gaps of sometimes several hou
rs\, singularities arise due to unresolvable parameters inside these gaps.
This issue as well as the geometric datum deficiency require additional i
nformation to determine the VLBI target parameters\, e.g\, Earth orientati
on parameters\, as well as the celestial and terrestrial reference frames.
For this reason\, it is necessary to constrain the respective parameters
in the solution. \n\nIn this paper we analyze the singularities which aris
e within the geodetic VLBI data analysis and show the ramifications of tra
ditional constraining. Furthermore\, we give suggestions to optimize the l
east squares solution with regard to constraining the VLBI solution. The e
ffects of various approaches are validated by the analysis of continuous V
LBI campaigns.\n\nhttps://events.saip.org.za/event/56/contributions/4678/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4678/
END:VEVENT
BEGIN:VEVENT
SUMMARY:An Inequality Constrained Least-Squares approach as an alternative
estimation procedure for atmospheric parameters from VLBI observations
DTSTART;VALUE=DATE-TIME:20160317T101500Z
DTEND;VALUE=DATE-TIME:20160317T103000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4679@events.saip.org.za
DESCRIPTION:Speakers: Sebastian Halsig (Institute of Geodesy and Geoinform
ation\, University of Bonn)\nOn its way through the atmosphere\, the signa
ls of space-geodetic techniques\, such as GNSS or VLBI\, are delayed and a
ffected by bending and attenuation effects relative to a theoretical path
in vacuum. Changing atmospheric conditions contribute considerably to the
error budget of the observations. At the same time\, space-geodetic techni
ques play a crucial role in the understanding of the Earth's atmosphere\,
because atmospheric parameters can be linked to the water vapor content in
the atmosphere.\n\nIn the VLBI data analysis\, the tropospheric delay is
usually taken into account by applying an adequate model for the hydrostat
ic component and by additionally estimating zenith wet delays for the high
ly variable wet component. Unfortunately\, the standard Least-Squares appr
oach sometimes leads to negative estimates\, which would be equivalent to
negative water vapor in the atmosphere and does of course not reflect the
meteorological and physical conditions in a plausible way.\n\nTo cope with
this phenomenon\, we introduce an Inequality Constrained Least-Squares (I
CLS) method from the field of convex optimization and use inequality const
raints to force the tropospheric parameters to be non-negative allowing fo
r a more realistic tropospheric parameter estimation in a meteorological s
ense. The impact of the ICLS approach will be validated with regard to sta
tion positions. Since deficiencies in the a priori hydrostatic modeling ar
e almost fully compensated by the tropospheric estimates\, the ICLS approa
ch urgently requires suitable a priori hydrostatic delays. Thus\, we prese
nt strategies to deal with missing or incorrect a priori model data.\n\nht
tps://events.saip.org.za/event/56/contributions/4679/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4679/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Application of Kalman filtering for the determination of a VLBI te
rrestrial reference frame
DTSTART;VALUE=DATE-TIME:20160316T121500Z
DTEND;VALUE=DATE-TIME:20160316T123000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4680@events.saip.org.za
DESCRIPTION:Speakers: Benedikt Soja (GFZ German Research Centre for Geosci
ences)\nTerrestrial reference frames (TRF) of high quality are indispensab
le for many geoscientific and geodetic applications including very long ba
seline interferometry (VLBI) data analysis. While secular station coordina
te changes\, e.g. due to tectonic plate motion\, can be well represented b
y a linear model\, current accuracy requirements also demand modeling of n
on-linear signals such as surface deformations due to mass loading or post
-seismic deformations. The ITRF2014\, for instance\, includes coefficients
for exponential and logarithmic functions after major earthquakes. Anothe
r approach\, used for the determination of JTRF2014\, is the application o
f Kalman filtering that allows post-seismic displacements to be accounted
for in a non-parametric manner.\n\nIn this paper\, we portray a TRF soluti
on solely based on VLBI data\, employing Kalman filtering and smoothing fo
r the computation of session-wise coordinates of more than hundred VLBI ra
dio telescopes over more than 30 years. By using a random walk process\, n
on-linear coordinate changes are modeled stochastically. The noise model i
s derived from loading deformation time series that are not included in th
e model for the station motion (i.e.\, non-tidal atmosphere\, non-tidal oc
ean\, and continental water storage loading). This stochastic model alone
is not able to adapt to the large coordinate variations that can happen af
ter major earthquakes. Therefore\, we additionally increase the process no
ise in the periods following earthquakes based on the amplitude of the est
imated coordinate jumps\, introducing the epochs of the seismic events as
prior information.\n\nWe compare our Kalman filtered and smoothed VLBI-TRF
to a classical least squares VLBI solution calculated by the VieVS@GFZ so
ftware\, based on linear segments between episodic events. Additionally\,
multi-technique TRF\, such as the ITRF2014 and JTRF2014\, are included in
the comparisons\, especially for assessing the different approaches of mod
eling post-seismic deformations.\n\nhttps://events.saip.org.za/event/56/co
ntributions/4680/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4680/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Results from the VLBI Analysis Software Comparison Campaign 2015
DTSTART;VALUE=DATE-TIME:20160316T094000Z
DTEND;VALUE=DATE-TIME:20160316T095500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4681@events.saip.org.za
DESCRIPTION:Speakers: Grzegorz Klopotek (Chalmers University of Technology
)\nThe IERS Conventions contain recommendations\, definitions and models f
or space geodetic techniques including geodetic VLBI. In practice\, differ
ent analysis software packages follow different estimation methods\, use a
variety of different correction models and sometimes adhere to convention
s that might not be the latest. This may lead to differences in the result
s that should not appear among the software packages dealing with the same
observational data-set. Consistency of geodetic VLBI analysis is especial
ly important for the VLBI Global Observing System (VGOS)\, for which we ne
ed station position and velocity accuracies of 1 mm and 0.1 mm per year\,
respectively.\nThe aim of the VLBI Analysis Software Comparison Campaign 2
015 (VASCC2015) was to compare different VLBI analysis software packages o
n the basis of computed theoretical delays. Two networks\, one in the nort
hern and one in the southern hemisphere\, were scheduled in a way so that
in each network a single source could be tracked continuously. In total fi
fteen consecutive 24 hour sessions with one minute observation resolution
formed the base of this comparison campaign. More than eight research grou
ps and institutes participated in this project\, which allowed us to compa
re software packages that are used in operational VLBI analysis as well as
those being currently under development. \nWe are going to present the fi
rst results and the outcomes of this project and we show how well the indi
vidual software packages agree. We will discuss discrepancies between anal
ysis software packages and reveal where those differences are coming from.
Moreover\, we are going to evaluate whether these discrepancies are small
enough to be neglected for reaching the VGOS goals.\n\nhttps://events.sai
p.org.za/event/56/contributions/4681/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4681/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Robust ambiguity estimation for automated analysis of Intensive se
ssions
DTSTART;VALUE=DATE-TIME:20160316T092500Z
DTEND;VALUE=DATE-TIME:20160316T094000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4682@events.saip.org.za
DESCRIPTION:Speakers: Niko Kareinen (Chalmers University of Technology)\nR
obust and automatic estimation of ambiguities is one of the main requireme
nts for a fully automated analysis of Intensive sessions. We apply the L1-
norm minimization to ambiguity estimation and ionosphere calibration using
the c5++ analysis software. This study includes IVS Intensive sessions on
the Kokee-Wettzell baseline from 2001 to 2015 where Version-1 database ar
e accessible. Version-1 corresponds to correlation output meaning the ambi
guity elimination and the ionosphere calibration need to be performed prio
r to parameter estimation. In total we use 1778 databases in this study. T
he analysis is done in two steps. First the session is processed in automa
tic mode to resolve the ambiguities and estimate the ionospheric delays. T
hen\, we estimate UT1-UTC using the ionosphere-free databases. In standard
c5++ both steps use the well-known least-squares optimization (L2-norm mi
nimization) to fit the model to the observations. We introduce the L1-norm
minimization into the first step and then estimate UT1-UTC using the leas
t-squares method. The results are compared with databases analysed using l
east-squares in both steps. The performance differences are assessed by in
vestigating the session fit and the respective UT1-UTC estimates. Further
details can be found in [1].\n\n[1] Kareinen et al. (2015)\, Robust ambigu
ity estimation for automated analysis of Intensive sessions\, manuscript s
ubmitted to Computers & Geosciences.\n\nhttps://events.saip.org.za/event/5
6/contributions/4682/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4682/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Real-time e-VLBI in the EVN and software correlation at JIVE
DTSTART;VALUE=DATE-TIME:20160316T074500Z
DTEND;VALUE=DATE-TIME:20160316T080000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4683@events.saip.org.za
DESCRIPTION:Speakers: Bob Campbell (JIVE)\nReal-time e-VLBI continues to f
orm an integral element of the European VLBI Network (EVN)\, accounting fo
r about a quarter of all EVN hours and providing unique rapid-response cap
abilities to transient events as well as the opportunity for higher-cadenc
e observations compared to the standard EVN sessions that fall three times
per year. The EVN software correlator at JIVE (SFXC) can currently proce
ss real-time correlation for a 14-station array at 1 Gbps with cross-polar
izations. Tests show that 8-9 stations at 2 Gbps can also be sustained. \
n\n The classes of e-EVN proposals has grown to include two new types of
triggered observations. "Generic triggers" allow a set of potential targe
ts that can not be defined explicitly at proposal time\, which opens e-EVN
observations to newly discovered transient sources. "Automatic triggers"
can receive and adjudicate trigger requests without human intervention (e
.g.\, by a program listening for specified VO events)\, and can similarly
create and distribute an appropriately modified schedule to override the
currently running observations (for stations permitting such remote interv
entions). This can provide significantly faster response -- down to 10 mi
nutes\, as compared to the 29 hr for traditional triggers. Running jive5a
b at the correlator and the stations enables simultaneous real-time e-VLBI
correlation and recording (at the correlator and/or at the stations). Th
is permits\, among other applications\, commensal searches for transients
via analysis of the real-time autocorrelations\, the result of which could
trigger a wide-field correlation of the baselines for the corresponding t
ime-range\, detached from the on-going real-time correlation. \n\n SFXC h
as processed all EVN disk-based observations correlated at JIVE since the
May/June 2012 session\, and all e-EVN observations since December 2012. I
t removes the physical limitations to the number of stations\, the channel
& total bit-rates\, and the number of frequency points. It also applies
a purely station-based fringe rotation\, decouples the correlation and del
ay-tracking FFT sizes\, and permits choice of the spectral-windowing funct
ion. It can correlate observations containing a mixed number of channels\
, mixed channel bandwidths\, and mis-matched side-bands -- accelerating de
velopments in various digital back-ends has led to this being a quite rout
ine situation. SFXC opens up new astronomical areas for correlation at JI
VE via pulsar gating/binning (including coherent de-dispersion)\, multiple
phase-center output within a wider field\, spectral zooming\, space VLBI
(comprising both antennas in orbit such as RadioAstron\, and near-field ta
rgets in the solar-system)\, and a phased-up mode. Each of these has been
exploited by proposal-driven user experiments over the past couple years.
\n\nhttps://events.saip.org.za/event/56/contributions/4683/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4683/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Plan for a VLBI antenna in Tahiti from 2018
DTSTART;VALUE=DATE-TIME:20160314T083500Z
DTEND;VALUE=DATE-TIME:20160314T085000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4684@events.saip.org.za
DESCRIPTION:Speakers: richard Biancale (CNES/GRGS)\nIt is known that the V
LBI Global Observing System (VGOS) network suffers from a lack of implemen
tation in the South Pacific area. It is why GRGS was considering setting u
p a VLBI antenna in Tahiti in cooperation with NASA.\nThere is an existing
geodetic observatory (OGT) in the campus of the French Polynesian Univers
ity (UPF) which was created in 1998 in a tripartite cooperation between UP
F\, NASA and CNES. It gathers several geodetic instruments such as the NAS
A’s MOBLAS-8 station\, a DORIS master beacon and several GNSS receivers.
But there is not enough room to install a VLBI antenna\, moreover in an e
nvironment surrounded by many buildings or houses.\nThat is why we explore
d other hosting possibilities for a NASA's VLBI2010 antenna and other new
geodetic instruments (SLR-NG\, Regina GNSS\, DORIS). Finally\, we could fi
nd an adequate ground on the site of the Tahiti Nui Telecom (TNT) company.
The project was submitted then to the French involved organisms: CNES\, I
NSU-CNRS\, OCA… and to NASA for further implementing studies.\nWe propos
e to describe the state-of-the-art of this project for a possible realizat
ion from 2018 in addition to the core space geodetic network. Some simulat
ion results will be presented as well in support to this project.\n\nhttps
://events.saip.org.za/event/56/contributions/4684/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4684/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Accurate spacecraft positioning by VLBI imaging
DTSTART;VALUE=DATE-TIME:20160317T143000Z
DTEND;VALUE=DATE-TIME:20160317T144500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4685@events.saip.org.za
DESCRIPTION:Speakers: Weimin Zheng (Shanghai Astronomical Observatory\,CAS
)\nVLBI is a radio astronomy tool with very high space angle resolution an
d Chinese VLBI Network has played a important roles in the Chang’E serie
s lunar mission. In the upcoming Chinese lunar and deep space missions\, h
igher angular position ability is needed. For these reasons\, we carried o
ut research on accurate spacecraft positioning and conducted several space
vehicles phase-referencing positioning experiments using the Chinese VLBI
network and other VLBI antennas. The near-field target uvw prediction met
hod is adopted. This paper shows the VLBI spacecraft imaging position expe
riment results of several ChangE lunar probes\, the Mars Express probe and
the Rosetta probe. The results validate VLBI with the mill-arcsecond leve
l position ability for deep space probes.\n\nhttps://events.saip.org.za/ev
ent/56/contributions/4685/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4685/
END:VEVENT
BEGIN:VEVENT
SUMMARY:INVITED TALK: Delay & Phase Calibration in VGOS Post-proces
sing
DTSTART;VALUE=DATE-TIME:20160314T124500Z
DTEND;VALUE=DATE-TIME:20160314T131000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4686@events.saip.org.za
DESCRIPTION:Speakers: Roger Cappallo (MIT Haystack Observatory)\nNow that
significant amounts of data have begun to flow through the VGOS pipeline\,
we are encountering real-world issues in the fringe-fitting process. In o
rder to create a high-quality geodetic observable one wants to minimize th
e sensitivity of group delay to instrumental parameters that may change ov
er time\, while at the same time maximizing the amount of information that
is extracted. This talk will address a number of topics relevant to those
goals\, such as matching of delays in polarization products and receiving
bands\, and coherent phasing of the four polarization products. Software
that automates the somewhat tedious determination of the calibration param
eters will be described. The accurate removal of the effect of the ionosph
ere is central to a precision observable\, and our procedures and experien
ce in doing so will be discussed.\n\nhttps://events.saip.org.za/event/56/c
ontributions/4686/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4686/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Combination of the two radio space geodetic techniques with VieVS
during CONT14
DTSTART;VALUE=DATE-TIME:20160316T124500Z
DTEND;VALUE=DATE-TIME:20160316T130000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4687@events.saip.org.za
DESCRIPTION:Speakers: Younghee Kwak (Technische Universität Wien)\nUnlike
CONT11\, CONT14 does not have official information on common frequency st
andards for co-location sites. Nevertheless\, according to Kwak et al. (20
15)\, we have a possibility to find the co-located sites\, which used the
same clocks\, through comparing clock rates from single technique solution
s. Moreover\, CONT14 includes co-located VLBI radio telescopes\, i.e. HOBA
RT26 and HOBART12. Therefore\, it is a good test bed to develop the analys
is strategy for future twin/sibling telescopes.\nIn this study\, we comput
e GNSS single differences between the ranges from two stations to a satell
ite\, using phase measurements with most of the errors corrected by the c5
++ software. We estimate station coordinates and site common parameters\,
i.e. zenith wet delays\, troposphere gradients and clock parameters\, with
the Vienna VLBI Software. Common clock parameters are limited to the site
s that are sharing the same frequency standard during CONT14. Local tie ve
ctors are introduced as fictitious observations for co-located instruments
\, GNSS-VLBI and even VLBI-VLBI\, i.e. at Hobart. In this presentation\, w
e show the comparison results between the combination solutions and the si
ngle technique solutions in terms of station position repeatability during
15 days.\n\nhttps://events.saip.org.za/event/56/contributions/4687/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4687/
END:VEVENT
BEGIN:VEVENT
SUMMARY:VGOS observations with GGAO12M\, Westford\, and the new Kokee 12m
antenna
DTSTART;VALUE=DATE-TIME:20160314T094500Z
DTEND;VALUE=DATE-TIME:20160314T100000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4688@events.saip.org.za
DESCRIPTION:Speakers: Arthur Niell (MIT Haystack Observatory)\nThe GGAO 12
m and Westford 18m antennas are instrumented with the broadband signal cha
in to provide VGOS capability. These antennas have been making VGOS geode
tic observations for more than a year. Approximately seventeen one- to tw
enty-four-hour VGOS sessions were conducted in 2015 to develop and test ma
ny of the procedures needed for an operational program\, including schedul
ing\, unattended observing\, correlation\, and preliminary data analysis t
hrough geodetic estimation. Currently\, after the creation of a schedule\
, the session can be run unattended following checkout of the antenna sens
itivity and pointing. The Field System controls the Backend\, including t
he four UpDownConverters (for band frequency selection)\, the four RDBE-G
digital backends in polyphase filter bank (PFB) mode\, and the Mark6 recor
der. For correlation direct playback from the Mark6 is being tested. The
broadband delay observable is derived by combining the four linear polariz
ation cross-products in all four RF bands and simultaneously estimating th
e phase dispersion due primarily to the ionosphere. With some slight modi
fications of the database creation and editing programs it has been possib
le to do geodetic analysis of most of the sessions using nuSolve. Prelimi
nary analysis of the first eleven sessions gives a weighted RMS deviation
of 2 mm from the mean baseline length (600 km) for those one-hour sessions
.\n\nThe Kokee 12m VGOS antenna\, designed and manufactured by InterTronic
s Solutions\, has been completed\, and the broadband signal chain\, built
by Haystack\, will be installed in early 2016. It is expected that Kokee1
2m will be added to the GGAO-Westford observations by February\, and the p
rocedures developed for the GGAO-Westford sessions will form the basis for
observations with the three-station network.\n\nResults for both the GGAO
-Westford series and for observations with all three antennas will be repo
rted.\n\nhttps://events.saip.org.za/event/56/contributions/4688/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4688/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ultra-rapid earth rotation determination with VLBI during CONT11 a
nd CONT14
DTSTART;VALUE=DATE-TIME:20160317T123000Z
DTEND;VALUE=DATE-TIME:20160317T124500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4689@events.saip.org.za
DESCRIPTION:Speakers: Rüdiger Haas (Chalmers University of Technology)\nI
n 2007 the Geospatial Information Authority of Japan (GSI) and the Onsala
Space Observatory (OSO) started a collaboration project aiming at determin
ing the earth rotation angle\, usually expressed as UT1-UTC\, in near real
-time. In the beginning of this project dedicated one hour long one-baseli
ne experiments were observed periodically using the VLBI stations Onsala (
Sweden) and Tsukuba (Japan). The strategy is that the observed VLBI data a
re sent in real-time via the international optical fibre backbone to the c
orrelator at Tsukuba where the data are correlated with a software correla
tor and analyzed in near-real time with the c5++ VLBI data analysis softwa
re\, thus producing UT1-UTC results with very low latency. The latency bet
ween the observation at the stations and the determination of UT1-UTC is o
n the order of a few minutes\, thus we can talk about an ultra-rapid deter
mination of UT1-UTC. An offline version of this strategy was adopted in 20
09 for the regular VLBI intensive series INT-2\, organized by the Internat
ional VLBI Service for Geodesy and Astrometry (IVS)\, that involves Wettze
ll (Germany) and Tsukuba. Since March 2010 the INT-2 is using real-time e-
transfer\, too\, and since June 2010 also automated analysis. Starting in
2009 the ultra-rapid approach was applied to regular 24 hour long IVS VLBI
-sessions that involve Tsukuba and Onsala\, so that ultra-rapid UT1-UTC re
sults can be produced already during ongoing VLBI-sessions. This strategy
was successfully operated during the 15 days long continuous VLBI campaign
s CONT11 and CONT14. In this presentation we give an overview of the ultra
-rapid concept\, present the results derived during CONT11 and CONT14\, an
d compare these ultra-rapid results to results derived from post-processin
g.\n\nhttps://events.saip.org.za/event/56/contributions/4689/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4689/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Effects on Earth Orientation Parameters caused by different analys
is options
DTSTART;VALUE=DATE-TIME:20160317T124500Z
DTEND;VALUE=DATE-TIME:20160317T130000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4690@events.saip.org.za
DESCRIPTION:Speakers: Robert Heinkelmann (GFZ Potsdam)\nThe Earth Orientat
ion Parameters (EOP) are arguments of the time-dependent rotation matrices
describing the difference in orientation between the Earth crust-fixed re
ference system\, ITRS\, and the space-fixed reference system\, ICRS. Very
Long Baseline Interferometry (VLBI) is the technique that connects the rea
lizations of ITRS and ICRS in terms of orientation directly on the observa
tion level. Many applications in spacecraft navigation\, fundamental astro
nomy\, astrometry\, and geosciences depend on the provision of the Earth O
rientation Parameters (EOP). Currently\, under the IAG/IAU Joint Working G
roup on the Theory of Earth Rotation\, activities are supported that foste
r the advance on the theory of Earth rotation. Some components of the Eart
h rotation\, such as the Free Core Nutation (FCN)\, are not well predictab
le but rely entirely on empirical determination through VLBI. In our paper
we step-by-step alternate different analysis options\, such as a priori d
ata and models\, and quantify the resulting effects on the EOP. Our approa
ch is purely empirical: we will alternate certain analysis options and ass
ess the differences with respect to the reference solution that adheres to
IERS Conventions (2010) and applies the parameterization that was used in
our contribution to ITRF2014\, the next realization of the ITRS. For demo
nstration we analyze current regular International VLBI Service for Geodes
y and Astrometry (IVS) sessions: IVS-R1 and –R4. The IAG flagship compon
ent GGOS (Global Geodetic Observing System) aims to realize EOP with an ac
curacy of 1 mm\, i.e. about 30 microarcseconds. This accuracy will be used
as a threshold to interpret the significance of the effects.\n\nhttps://e
vents.saip.org.za/event/56/contributions/4690/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4690/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Current status of an implementation of a system monitoring for sea
mless auxiliary data at the Geodetic Observatory Wettzell
DTSTART;VALUE=DATE-TIME:20160315T080000Z
DTEND;VALUE=DATE-TIME:20160315T081500Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4691@events.saip.org.za
DESCRIPTION:Speakers: Alexander Neidhardt (Technische Universität Münche
n\, Geodätisches Observatorium Wettzell)\nA first test implementation of
an auxiliary data archive is tested at the Geodetic Observatory Wetttzell.
It is software which follows-on the Wettzell SysMon\, extending the datab
ase and data sensors with the functionalities of a professional monitoring
environment\, named Zabbix. Some extensions to the remote control server
on the NASA Field System PC enable the inclusion of data from external ant
ennas. The presentation demonstrates the implementation and discusses the
current possibilities to encourage other antennas to join the auxiliary ar
chive.\n\nhttps://events.saip.org.za/event/56/contributions/4691/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4691/
END:VEVENT
BEGIN:VEVENT
SUMMARY:IVS Combiantion Center at BKG: Options and functions of the revise
d website
DTSTART;VALUE=DATE-TIME:20160314T150000Z
DTEND;VALUE=DATE-TIME:20160314T160000Z
DTSTAMP;VALUE=DATE-TIME:20240319T093112Z
UID:indico-contribution-56-4692@events.saip.org.za
DESCRIPTION:Speakers: Sabine Bachmann (BKG)\nThe International VLBI Servic
e for Geodesy and Astrometry (IVS) Combination Center at the Federal Agenc
y for Cartography and Geodesy (BKG\, Germany) is responsible for generatin
g combined Earth orientation parameter (EOP) products. Additionally\, res
ults of combined station coordinates and a terrestrial reference frame bas
ed on VLBI observations are generated. For providing information on the co
mbination\, the Combination Center maintains the CCIVS website where resul
ts\, activities and new products are presented. Due to the implementation
of a new content management system\, the website was revised and new funct
ions were added. A new search function was realized to find individual ter
ms of the page content. A glossary\, a sitemap and simplified standardized
contact forms improve and enhance the handling of the website. The new de
sign is clear\, color matched and fills up the text content with informati
ve graphics and pictures. Information about the results on the IVS contrib
ution to the ITRF2014 were introduced and all existing data is regularly u
pdated. The website is reachable over the Internet link ccivs.bkg.bund.de
or www.ccivs.bkg.bund.de. In the future all users may get in contact with
the Combination Center via the simplified contact forms or the new central
email address ccivs@bkg.bund.de. The revised website with old and new opt
ions\, functions and features is presented.\n\nhttps://events.saip.org.za/
event/56/contributions/4692/
LOCATION:
URL:https://events.saip.org.za/event/56/contributions/4692/
END:VEVENT
END:VCALENDAR