Subject: [IGSMAIL-0433] ITRF92 FIXED/CONSTRAINED COORDINATES
From: Analysis Center Coordinator
Date: Mon, 10 Jan 1994 12:18:27 PST

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IGS Electronic Mail      Mon Jan 10 12:18:27 PST 1994      Message Number 0433
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Author: Analysis Center Coordinator
Subject: ITRF92 FIXED/CONSTRAINED COORDINATES

Dear  colleagues,

After discussions with several Analysis Centres  and the TRF Section of the
IERS it is recommended that the corrected ITRF92 coordinates  & velocities for
the thirteen stations as given in the IGSMAIL #430 be fixed or constrained in
the IGS processing, starting with the GPS week 730 (January 2-8, 1993).

Please note that in this set , which is given for the epoch 1994.0, the
positions and velocities of TROM and YELL have been corrected with respect to
the original ITRF92 coordinate/velocities set. Also please  note that stations
TIDB now refers to the monument (ant. height 0.092m) rather than to ARP as
given previously (e.g. IGSMAIL#263). The ITRF92(1994.0) coordinates for the
remaining stations can be found in IGSMAIL#421 . The associated antenna
heights can be obtained (by anonymous ftp) from :

         sideshow.jpl.nasa.gov (128.149.70.41)
  file: /igscb/station/tie/localtie.tab

It is also recommended that several days (preferably one week) is processed
with both the new and old sets of fixed/constrained coordinates. Then either
both EOP solutions, or an average EOP offset and sigmas should be submitted to
IERS and noted in the summary report.

Sorry for the delay and inconvenience this might have caused.

Jan Kouba
Geodetic Survey of Canada
Ottawa, Ontario, Canada
Internet: [email-masked]