Technical description of solution bkg2013a.crf
1. Purpose of solution: CRF
2 - Analysis Center: Federal Agency for Cartography and Geodesy (BKG Leipzig) and
Institute of Geodesy and Geoinformation of the University of Bonn (IGGB)
3. Short narrative description of solution:
VLBI data from Jan 1984 to OCT 2013 were used for this solution.
The orientation of CRF is defined by no-net-rotation constraints
for 295 defining sources related to the ICRF2 catalogue. The TRF is defined
by no-net-translation and rotation constraints for the coordinates and velocities
of 25 sites related to VTRF2008a. The values of the official list of VLBI antenna axis
offsets issued by the IVS Analysis Coordinator were used from IVS-table antenna-info.txt
(http://lupus.gsfc.nasa.gov/IVS-AC_data_information.htm).
Mean pole coordinates used for computation of pole tide deformation were applied
according to IERS Conventions 2003 (eq. 23a, 23b). The Vienna mapping function (VMF1) is
applied for troposphere correction modelling. Positions of GILCREEK, HRAS_085, PIETOWN are
modeled with spline.
The atmospheric pressure loading time series provided by the Goddard VLBI group
which are available on the Web at http://lacerta.gsfc.nasa.gov/aplo (Petrov & Boy, 2004) are used.
A priori short-period tidal variations in EOP were taken into account in accordance with IERS
Conventions 2003. Ocean loading model FES2004 computed by H. G. Scherneck was used.
Thermal expansion modelling developed by Axel Nothnagel (2009) was used.
The values of station eccentricities were taken from the official IVS-table ECCDAT.ecc.
4. Estimated parameters:
a. celestial frame: right ascension, declination
b. terrestrial frame: X, Y, Z, Xdot, Ydot, Zdot
and coordinates series of stations
AIRA CHICHI10 CTVASTJ DSS13 HART15M KASHIM11 KASHIM34
KOGANEI KUNMING PT_REYES SINTOTU3 SEST TIGOCONC TSUKUB32 UCHINOUR
VERAISGK VERAMZSW WIDE85_3 YEBES40M
estimated in respective session,
spline coefficients for stations GILCREEK, HRAS_085, PIETOWN
c. Earth orientation: X-pole, Y-pole, UT1-TAI, Xdot, Ydot, UT1dot,
X-nutation, Y-nutation
d. zenith troposphere: 1h piece-wise linear functions,
rate constraint generally 50 ps/hour,
VMF1 wet partial derivative (segmented)
e. troposphere gradient: east and north offset,
offset constraint 0.5 mm,
rate constraint 2.0 mm/day
f. station clocks: 1h piece-wise linear functions,
rate constraint generally 5.E-14
g. baseline clocks: set in initial analysis - usually used
h. other: No
5. Celestial reference frame:
a. a priori source positions: ICRF2
b. source positions adjusted in solution: Yes
c. definition of orientation: no-net-rotation of sources with respect
to ICRF2 for 295 defining sources marked in the ITRF2 catalogue
6 - Terrestrial reference frame:
a. a priori station positions: VTRF2008a
b. a priori station velocities: VTRF2008a
c. reference epoch: 2000.0
d. definition of origin, orientation, and their time evolution:
no-net-translation and no-net-rotation of position with respect to
VTRF2008a for 25 stations:
ALGOPARK BR-VLBA DSS45 FD-VLBA FORTLEZA HARTRAO HOBART26
KASHIMA KAUAI KOKEE LA-VLBA MATERA MK-VLBA NL-VLBA NOTO
NRAO20 NRAO85_3 NYALES20 ONSALA60 RICHMOND SANTIA12 SC-VLBA SESHAN25
WESTFORD WETTZELL
no-net-translation and no-net-rotation of velocity with respect to
VTRF2008a for the same 25 stations:
ALGOPARK BR-VLBA DSS45 FD-VLBA FORTLEZA HARTRAO HOBART26
KASHIMA KAUAI KOKEE LA-VLBA MATERA MK-VLBA NL-VLBA NOTO
NRAO20 NRAO85_3 NYALES20 ONSALA60 RICHMOND SANTIA12 SC-VLBA SESHAN25
WESTFORD WETTZELL
e. stations with nonlinear velocities:
GILCREEK, HRAS_085, PIETOWN
7. Earth orientation:
a. a priori precession/nutation model: IAU2000A Precession-Nutation,
IERS 2003 implementation, modified using the IAU2006
precession model
b. a priori short-period tidal variations in X, Y and UT1 due to short
period tidal and nutation effects were applied as recommended in the
IERS 2003 Conventions
c. a priori UT1 and polar motion: usno_finals.data
(http://gemini.gsfc.nasa.gov/solve_save/usno_finals.erp)
d. EOP estimation: X, Y, UT1, Xdot, Ydot, UT1dot, X-nutation, Y-nutation, each session
for the middle epoch of it, and X-nutation and Y-nutation are relative to
IAU2000A/2006 Nutation/Precession models,
also X, Y, UT1, Xdot, Ydot, UT1dot, Deps, Dpsi, each session
for the middle epoch of it, and Deps and Dpsi are relative to the
IAU 1976 precession and IAU 1980 nutation models.
8. A priori geophysical models:
a. troposphere: hydrostatic component with VMF1 mapping function
b. solid Earth tide: IERS Conventions
c. ocean loading: FES2004
d. atmosphere loading: atmospheric pressure loading time series provided by GSFC
(available at http://lacerta.gsfc.nasa.gov/aplo/aplo_bds.tar.bz2)
9. Data type: Group delays
10. Data editing: 5 deg elevation cutoff, editing of outliers
during adjustment when necessary
11. Data weighting: Observations are weighted using std reported
in observational files; re-weighting iteration for each session
to achieve the chi-square unity.
12. Standard errors reported: Reported formal errors are derived from
least-squares estimation propagated from data uncertainties and
weighted as discussed in #11.
13 Software: Calc 10, SOLVE release: 2010.05.21
References:
Axel Nothnagel (2009) Conventions on thermal expansion
modelling of radio telescopes for geodetic and astrometric VLBI;
Journal of Geodesy, Vol. 83(3), 787-792, DOI: 10.1007/s00190-008-0284-z.
L. Petrov, J.-P. Boy, Study of the atmospheric pressure loading signal in VLBI observations,
Journal of Geophysical Research, 10.1029/2003JB002500, Vol. 109, No. B03405, 2004.