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[IGSMAIL-5400]: igs05_1390.atx - New release of the absolute IGS antenna correction file

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IGS Electronic Mail      29 Aug 23:48:53 PDT 2006      Message Number 5400
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Author: Ralf Schmid


Dear IGS colleagues!

The absolute IGS antenna correction file (igs05_wwww.atx) has again been updated. The new release is called 'igs05_1390.atx'. This is expected to be one of the last updates before the official switch from relative to absolute antenna phase center corrections that will take place together with the adoption of ITRF2005 (see IGSMAIL-5189: http://igscb.jpl.nasa.gov/mail/igsmail/2005/msg00111.html ).


1) New GLONASS offsets

As the offset values for the two GLONASS-M satellites launched in December 2005 (R713, R714) were not available in igs05_1365.atx, CODE computed antenna offsets for all GLONASS satellites using the observation data till the beginning of August 2006:

New solution in 2006 AUG 21 | Values from IGS05_1365.atx | Diff Diff
SVN PRN Off[mm] | | Off nobs
701 6 2194.7 +- 11.1 nobs: 320| 6 2187.6 +- 16.7 nobs: 193 | 7.1 127
711 5 1914.1 +- 16.7 nobs: 364| 5 1912.1 +- 21.6 nobs: 242 | 2.0 122
712 7 2323.2 +- 11.4 nobs: 289| 7 2330.3 +- 19.1 nobs: 162 | -7.1 127
713 24 2325.3 +- 14.6 nobs: 94| | -
714 23 2277.2 +- 30.5 nobs: 111| | -
783 18 1927.4 +- 8.8 nobs: 457| 18 1906.6 +- 11.0 nobs: 322 | 20.8 135
787 17 2055.9 +- 11.2 nobs: 412| 17 2044.6 +- 15.1 nobs: 275 | 11.3 137
788 24 2073.8 +- 15.3 nobs: 251| 24 2073.8 +- 15.3 nobs: 251 | 0 0
789 3 2004.6 +- 12.2 nobs: 386| 3 1971.0 +- 16.6 nobs: 256 | 33.6 130
791 22 2000.9 +- 8.8 nobs: 454| 22 1978.1 +- 11.5 nobs: 317 | 22.8 137
792 21 1975.4 +- 10.7 nobs: 424| 21 1954.7 +- 13.4 nobs: 284 | 20.7 140
793 20 2002.2 +- 8.8 nobs: 435| 23 1987.0 +- 10.5 nobs: 321 | 15.2 114
794 2 1957.7 +- 9.8 nobs: 359| 2 1939.2 +- 13.9 nobs: 228 | 18.5 131
795 4 2006.1 +- 9.7 nobs: 358| 4 2001.0 +- 15.0 nobs: 228 | 5.1 130
796 1 1944.4 +- 9.7 nobs: 346| 1 1924.2 +- 13.1 nobs: 219 | 20.2 127
797 8 1853.4 +- 12.9 nobs: 328| 8 1817.8 +- 20.3 nobs: 197 | 35.6 131
798 19 2039.0 +- 12.9 nobs: 165| 19 2044.4 +- 25.8 nobs: 25 | -5.4 140
Attention: 793 is also the old PRN23

It is worth mentioning that the offset values for the two latest GLONASS-M satellites (still marked unusable!) were derived exclusively from observation data of a relatively small number of all-in-view (AIV) tracking GNSS receivers of the IGS network.

The new values (based on about 15 months of data) are expected to be more accurate than the values contained in igs05_1365.atx (based on 10 months). Therefore, it was decided to replace ALL GLONASS z-offsets by the values listed above (However, the name of the model is kept. See below!).

The latest release contains new entries for R20 (R793), R23 (R714) and R24 (R713). In addition, decommission dates were added for R23 (R793) and R24 (R788).


2) New absolute ROBOT calibrations from Geo++ ( http://gnpcvdb.geopp.de/ )

Three antenna calibrations that were converted from relative field calibrations could be repclaced by robot calibrations from Geo++:

ASH700228A      NONE
ASH700228D      NONE
ASH700718B      NONE

These antenna types are not in use within the IGS at the moment. However, the reprocessing project starting soon should make use of the values. As the absolute file is still not official, the name of the antenna model ('igs05') is kept. (As soon as the IGS ANTEX file is officially used for the generation of IGS products, the name of the model will be changed, if existing values are replaced!)


3) Additional L1 antennas

The values for five additional L1 antennas were converted from relative NGS calibrations ( http://www.ngs.noaa.gov/ANTCAL/ ):

NOV501          NONE
NOV501+CR       NONE
NOV531          NONE
NOV531+CR       NONE
TPSLEGANT_G     NONE


4) Additional antennas recently added to rcvr_ant.tab ( http://igscb.jpl.nasa.gov/igscb/station/general/rcvr_ant.tab )

LEISR399_INTA   NONE
SOK702          NONE
TRM41249USCG    SCIT


5) 'Previously valid' antenna names removed

ASH701945.02B   NONE
ASH701946.012   NONE
ASH701946.022   NONE


After the official release of ITRF2005 within a few weeks the IGS will define the new IGS05 reference frame and will then officially switch to the absolute antenna model ('igs05').

The latest version of the model can be found at:

ftp://igscb.jpl.nasa.gov/igscb/station/general/pcv_proposed/igs05_1390.atx


With best regards from Munich,

Ralf Schmid
schmid @ bv.tum.de