In 2012, the activities of the BKG/IGGB VLBI Analysis Center, as in previous years, consisted of routine computations of Earth orientation parameter (EOP) time series and of a number of research topics in geodetic VLBI. The VLBI group at BKG continued its regular submissions of time series of tropospheric parameters and the generation of daily SINEX (Solution INdependent EXchange format) files. Quarterly updated solutions have been computed to produce terrestrial reference frame (TRF) and celestial reference frame (CRF) realizations. Routine computations of the UT1-UTC Intensive observations include all sessions of the Kokee-Wettzell and Tsukuba-Wettzell baselines and the networks Kokee-Svetloe-Wettzell and Ny-degAlesund-Tsukuba-Wettzell. The VLBI group at BKG developed a procedure to get the most probable station positions of Tsukuba after the earthquake on March 11, 2011 for the epochs of the Intensive sessions. The analysis of the Intensive sessions with station Tsukuba could be resumed in February 2012. At IGGB, the emphasis has been placed on individual research topics

Artz, Thomas

Engelhardt, Gerald

Leek, Judith

Nothnagel, Axel

Thorandt, Volkmar

Ullrich, Dieter

NASA Technical Reports Server

Bundesamt fu¨r Kartographie und Geoda¨sie BKG/IGGB Analysis Center
The BKG/IGGB VLBI Analysis Center
Volkmar Thorandt, Axel Nothnagel, Gerald Engelhardt, Dieter Ullrich, Thomas Artz,
Judith Leek
Abstract
In 2012, the activities of the BKG/IGGB VLBI Analysis Center, as in previous years, consisted of
routine computations of Earth orientation parameter (EOP) time series and of a number of research
topics in geodetic VLBI. The VLBI group at BKG continued its regular submissions of time series
of tropospheric parameters and the generation of daily SINEX (Solution INdependent EXchange for-
mat) files. Quarterly updated solutions have been computed to produce terrestrial reference frame
(TRF) and celestial reference frame (CRF) realizations. Routine computations of the UT1–UTC In-
tensive observations include all sessions of the Kokee–Wettzell and Tsukuba–Wettzell baselines and
the networks Kokee–Svetloe–Wettzell and Ny-A˚lesund–Tsukuba–Wettzell. The VLBI group at BKG
developed a procedure to get the most probable station positions of Tsukuba after the earthquake on
March 11, 2011 for the epochs of the Intensive sessions. The analysis of the Intensive sessions with
station Tsukuba could be resumed in February 2012. At IGGB, the emphasis has been placed on
individual research topics.
1. General Information
The BKG/IGGB VLBI Analysis Center has been established jointly by the analysis groups of
the Federal Agency for Cartography and Geodesy (BKG), Leipzig, and the Institute of Geodesy
and Geoinformation of the University of Bonn (IGGB). Both institutions cooperate intensely in the
field of geodetic VLBI. The responsibilities include both data analysis for generating IVS products
and special investigations with the goal of increasing accuracy and reliability. BKG is responsible
for the computation of time series of EOP and tropospheric parameters, for the generation of
SINEX files for 24-hour VLBI sessions and one-hour Intensive sessions, and for the generation of
quarterly updated global solutions for TRF and CRF realizations. Besides data analysis, the BKG
group is also responsible for writing schedules for the Tsukuba-Wettzell Int2 UT1-UTC observing
sessions. IGGB continues to host the office of the IVS Analysis Coordinator and carries out special
investigations within the technique of geodetic and astrometric VLBI. Details of the research topics
of IGGB are listed in Section 3.
2. Data Analysis at BKG
At BKG, the Mark 5 VLBI data analysis software system Calc/Solve, release 2010.05.21 [1], has
been used for VLBI data processing. It is running on a Linux operating system. As in the previous
releases, the Vienna Mapping Function (VMF1) has been implemented in a separate Solve version.
This modified version was used for all data analysis. The VMF1 data were downloaded daily
from the server of the Vienna University of Technology. Additionally, the technological software
environment for Calc/Solve has been refined to link the Data Center management with the pre-
and post-interactive parts of the EOP series production and to monitor all Analysis and Data
Center activities.
• Processing of correlator output
The BKG group continued the generation of calibrated databases for the sessions correlated at
IVS 2012 Annual Report 257
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BKG/IGGB Analysis Center Bundesamt fu¨r Kartographie und Geoda¨sie
the MPIfR/BKG Astro/Geo Correlator at Bonn (e.g., EURO, OHIG, and T2) and submitted
them to the IVS Data Centers.
• Scheduling
BKG continued scheduling the Int2 Intensive sessions, which are observed on the TSUKUBA-
WETTZELL baseline. Altogether 86 schedule files for this baseline were created in 2012.
Furthermore 30 schedule files for baseline KOKEE-WETTZELL (Int1 Intensive sessions on
weekends) were made available in the first half of the year 2012.
• BKG EOP time series
The BKG EOP time series bkg00013 was continued. The main features of this solution were
not changed. But three new VLBI stations (HART15M in South Africa, KOGANEI, and
UCHINOUR in Japan) could be included successfully in data processing.
Each time after the preprocessing of any new VLBI session (correlator output database
version 1), a new global solution with 24-hour sessions since 1984 was computed, and the
EOP time series bkg00013 was extracted. Altogether 4391 sessions were processed. The
main parameter types in this solution are globally estimated station coordinates and veloc-
ities together with radio source positions. The datum definition was realized by applying
no-net-rotation and no-net-translation conditions for 25 selected station positions and veloc-
ities with respect to VTRF2008a and a no-net-rotation condition for 295 defining sources
with respect to ICRF2. The station coordinates of the telescopes AIRA (Japan), CHICHI10
(Japan), CTVASTJ (Canada), DSS13 (USA), HOBART12 (Australia), KASHIM34 (Japan),
KATH12M (Australia), PT REYES (USA), SEST (Chile), SINTOTU3 (Japan), TIGO-
CONC (Chile), TSUKUB32 (Japan), WIDE85 3 (USA), VERAISGK (Japan), VERAMZSW
(Japan), WARK12M (New Zealand), YARRA12M (Australia), and YEBES40M (Spain) were
estimated as local parameters in each session. The three new VLBI stations HART15M
(South Africa), KOGANEI (Japan), and UCHINOUR (Japan) were modeled in the same
way.
• BKG UT1 Intensive time series
Regular analysis of the UT1-UTC Intensive time series bkgint09 was continued. The series
bkgint09 was generated with fixed TRF (VTRF2008a) and fixed ICRF2. The a priori EOP
were taken from finals USNO series [2]. The estimated parameter types were only UT1-TAI,
station clock, and zenith troposphere.
A semi-automatic process for handling the Intensive sessions (Int2/3) with station TSUKUBA
after the Japan earthquake has been developed. Using the latest global solution with 24-hour
sessions, including all available sessions with the station TSUKUBA, a particular a priori
coordinate file for each TSUKUBA Intensive session is created by interpolating the values
of the 24-hours TSUKUBA sessions. These files are used as input for the session by session
TSUKUBA Intensive cycle run. Finally, an IVS formatted EOP list is created and mixed
with the non-TSUKUBA IVS EOP list. These algorithms are included in the BKG post solve
procedure for establishing the IVS EOP solutions.
A total of 4048 UT1 Intensive sessions were analyzed for the period from 1999.01.01 to
2012.12.31.
• Quarterly updated solutions for submission to IVS
In 2012, one quarterly updated solution was computed for the IVS products TRF and CRF.
258 IVS 2012 Annual Report
Bundesamt fu¨r Kartographie und Geoda¨sie BKG/IGGB Analysis Center
There are no differences in the solution strategy compared to the continuously computed
EOP time series bkg00013. The results of the radio source positions were submitted to
IVS in IERS format. The TRF solution is available in SINEX format, version 2.1, and
includes station coordinates, station velocities, and radio source coordinates together with
the covariance matrix, information about constraints, and the decomposed normal matrix
and vector.
• Tropospheric parameters
The VLBI group of BKG continued regular submissions of long time series of tropospheric
parameters to the IVS (wet and total zenith delays and horizontal gradients) for all VLBI
sessions since 1984. The tropospheric parameters were extracted from the standard global
solution bkg00013 and transformed into SINEX format.
• Daily SINEX files
The VLBI group of BKG also continued regular submissions of daily SINEX files for all avail-
able 24-hour sessions for the IVS combined products and for the IVS time series of baseline
lengths. In addition to the global solutions, independent session solutions were computed for
the station coordinates, radio source coordinates, and EOP parameters including the X,Y-
nutation parameters. The a priori datum for TRF was defined by VTRF2008a, and ICRF2
was used for the a priori CRF information.
• SINEX files for Intensive sessions
The parameter types are station coordinates, pole coordinates and their rates, and UT1-TAI
and its rate. But only the normal equations stored in the SINEX files are important for
further intra-technique combination or combination with other space geodetic techniques.
3. Research Topics at IGGB
• Measurements of paraboloid deformations of the Effelsberg 100-m telescope with
a laser scanner
Variations in the focal length of a radio telescope have a direct effect on the delay observables
and on the position estimates. To study this, the paraboloid of the Effelsberg 100-m telescope
was scanned with a Leica HDS 6100 terrestrial Laser scanner. The scanner was mounted
head-down on an empty prime focus receiver box. Putting the receiver box in place gave the
scanner an almost unobstructed view of the main paraboloid. Scans were repeated in various
telescope elevation angles down to 7.5◦ with each data set consisting of 370 million points with
three polar components each. This is equivalent to one data point every 64 mm2. Proprietary
software of the instrument’s manufacturer was not able to handle this large amount of data;
thus, a dedicated C++ program running on a computer cluster was developed. As a first
result, the estimated focal length variations agree very well with the empirical model for
the sub-reflector displacement corrections. Since the accuracy of the individual distance
measurements of the scanner is only a few millimeters at a distance of 50-m, the ultimate
insight into the deformations cannot be achieved from individual data points but from a
surface fitting procedure to the residuals. Figure 1 shows the smoothed surface of the solid
part of the paraboloid at 30◦ elevation after a best fit paraboloid has been subtracted. In the
second and third quadrant, two reflector panels can be identified which had been displaced
on purpose by plus and minus 3 mm for a holography survey some time ago, validating the
IVS 2012 Annual Report 259
BKG/IGGB Analysis Center Bundesamt fu¨r Kartographie und Geoda¨sie
−40 −20 0 20 40
−40
−30
−20
−10
0
10
20
30
40
x [m]
y 
[m
]
 
 
w
 [m
m]
−5
−4
−3
−2
−1
0
1
2
3
4
5
Figure 1. Smoothed surface of the solid part of the paraboloid at 30◦ elevation after a best fit paraboloid
has been subtracted.
correctness of the whole procedure. The second blue spot at the third quadrant persists at
other elevation angles as well and must, thus, be a real local deformation.
• Automatic scheduling based on Singular Value Decomposition
The automatic scheduling method which selected the observations successively by means
of their impact factors has been developed to create schedules for VLBI Intensive sessions
replacing the participating single telescopes by twin telescopes successfully. For assessment
reasons, observations related to the created schedules have been simulated. The simulation
has been adapted for the special features of twin telescopes. However, the simulation has to
be improved some more to reach a well-founded evaluation of twin telescope observations in
Intensive sessions.
4. Personnel
Table 1. Personnel at BKG/IGGB Analysis Center.
Thomas Artz IGGB +49-228-733563 artz@igg.uni-bonn.de
Gerald Engelhardt BKG +49-341-5634438 gerald.engelhardt@bkg.bund.de
Judith Leek IGGB +49-228-733565 judith.leek@igg.uni-bonn.de
Axel Nothnagel IGGB +49-228-733574 nothnagel@uni-bonn.de
Volkmar Thorandt BKG +49-341-5634285 volkmar.thorandt@bkg.bund.de
Dieter Ullrich BKG +49-341-5634328 dieter.ullrich@bkg.bund.de
Reiner Wojdziak BKG +49-341-5634286 reiner.wojdziak@bkg.bund.de
References
[1] GSFC, NASA (2010): Release of Mark 5 VLBI Analysis Software Calc/Solve from May 21, 2010 (Web
reference: http://gemini.gsfc.nasa.gov/solve).
[2] USNO (2011): Earth orientation parameters series from finals USNO series 2011, (Web reference:
http://gemini.gsfc.nasa.gov/500/oper/solve apriori files/usno finals.erp).
260 IVS 2012 Annual Report


The BKG/IGGB VLBI Analysis Center

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