Subject: [IGSMAIL-0437] CODE
From: M. Rothacher
Date: Wed, 12 Jan 1994 9:30:25 PST

IGS Electronic Mail      Wed Jan 12  9:30:25 PST 1994      Message Number 0437
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Author: M. Rothacher
Subject: CODE: Change to ITRF92

Dear Colleagues,

starting January 1, 1994, we are using the ITRF92 site coordinates and 
the ITRF92 velocity field for the sites we fix or constrain in our
routine IGS processing. The official ITRF92 coordinates and velocities 
(IERS Technical Note 15) were changed according to the two updates by Zuheir 
Altamimi of December 23, 1993 (IGSMAIL #421) and January 10, 1994 (IGSMAIL 
#430). In our 3-days solutions we fix now the 13 sites selected at the
IGS Anaylsis Center Workshop in Ottawa:

               Site  Dome No.

               KOSG  13504M003
               MADR  13407S012
               TROM  10302M003
               WETT  14201M009
               HART  30302M002
               ALGO  40104M002
               FAIR  40408M001
               GOLD  40405S031
               KOKB  40424M004
               YELL  40127M003
               SANT  41705M003
               TIDB  50103M108
               YAR1  50107M004   

The antenna heights, antenna phase center offset corrections, marker names,
and receiver/antenna names are consistent with those given in the database 
at the IGS Central Bureau.

We recomputed the solutions from DOY 200 to DOY 365 of 1993 using the new
set of coordinates, velocities, and fixed sites. The following offsets
were computed between the old set of ERP (using ITRF91 coordinates and
different fixed sites) and the new set (ITRF92):
   
          Delta X-POLE (ITRF92-ITRF91) =  -0.88  mas  
          Delta Y-POLE (ITRF92-ITRF91) =  -0.60  mas
 
In addition to these offsets the new estimates of the y-pole coordinate 
show a better "long-term" consistency with the IERS values over the
second half of 1993.

                                           Markus Rothacher
                                           CODE IGS Analysis Center

NB:  The file COD07240.EPH (21-NOV-93, DOY 325) was replaced at the global 
     data centers. We detected that one epoch was missing in this file for 
     satellite PRN05 at 21:15:00.