[IGSMAIL-0691] Wk 747-750 Final IGS orbits

AC AC
Wed Jul 27 11:58:45 PDT 1994


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IGS Electronic Mail      Wed Jul 27 11:58:45 PDT 1994      Message Number 0691
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Author: AC Coordinator
Subject: Wk 747-750 Final IGS orbits


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IGS Final orbits/clocks completed and put onto CDDIS (Weeks 747 - 750)
                                                     ( May 01 - May 28, 1994)
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According to the recommendations of the Analysis Centre Workshop the IGS
Rapid Orbits were recomputed using up to date orbits and the final EOP values
of Bulletin B, published by IERS. ( Daily values, page 2 of Bull. B were
used). The EOP were corrected for the difference between the IERS pole series 
and ITRF as published in the IERS 1992 Annual Report (p. II-17, Table II-3),
so both the IGS orbits and associated ERP files are consistent with ITRF92
(current epoch).

We have downloaded all submitted ephemeris and ERP files from CDDIS before
the final orbit/clock combination to ensure that the sets are complete and up
to date. In the final combination we have largely followed the actions taken
during the Rapid orbit generation and since there were very few orbit
resubmissions, both the IGS Rapid  and Final orbits are virtually same except
for the the orientation difference (the current Bull.A and final Bull.B).
Orbit evaluation are also nearly the same, since we used centre specific ERP
in these long arc evaluations. For more information see the corresponding
summary files on CDDIS.

Starting with the GPS week 742 a new clock combination scheme was put in
place for the final orbit/clock combinations. The clock solution alignment
and centre clock weight assignment are based on non SA broadcast  satellite
corrections only (PRN12, 15, 20). This should result in more realistic and
objective clock weighting than employed before, provided that the non SA
satellites are representatives of each centre clock solution quality.

PRODUCTS GENERATED:

The resulting final IGS ephemeris and clocks are in daily files in the SP3
format. The sat. orb. accuracy codes displayed in the headers are based on
weighted RMS for each satellite. Note that each file contains all the submitted
satellites. If satellite or centre had to be excluded from the combination it
is noted in the summary file along with the reason for doing so.

The IGS FINAL ORBIT files generated and uploaded into CDDIS @ NASA/GSFC are:

IGS07470-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0747
IGS07480-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0748
IGS07490-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0749
IGS07500-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0750

IGS07477.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS07487.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS07497.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS07507.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)

IGS07477.SUM    Complete summary/statistics report
IGS07487.SUM    Complete summary/statistics report
IGS07497.SUM    Complete summary/statistics report
IGS07507.SUM    Complete summary/statistics report

The old Rapid Orbit files have been renamed (on CDDIS) to:
(Note this is temporary, based on discussions with AC and GB and may be
changed )

IGR07470-6.SP3   Rapid service orbits/clocks for days 0-6, week 747
IGR07480-6.SP3   Rapid service orbits/clocks for days 0-6, week 748
IGR07490-6.SP3   Rapid service orbits/clocks for days 0-6, week 749
IGR07500-6.SP3   Rapid service orbits/clocks for days 0-6, week 750

IGR07477.ERP     Rapid service EOP associated with the above orbits (Bull A)
IGR07487.ERP     Rapid service EOP associated with the above orbits (Bull A)
IGR07497.ERP     Rapid service EOP associated with the above orbits (Bull A)
IGR07507.ERP     Rapid service EOP associated with the above orbits (Bull A)

IGR07477.SUM     Rapid service complete summary/statistic report 
IGR07487.SUM     Rapid service complete summary/statistic report 
IGR07497.SUM     Rapid service complete summary/statistic report 
IGR07507.SUM     Rapid service complete summary/statistic report 

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REMARKS/CORRECTIONS:

None


[Mailed From: Jan Kouba <kouba at geod.emr.ca>]



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