Subject: [IGSMAIL-0952] Wk 0790-0794 IGS Final Orbits
From: AC Coordinator
Date: Wed, 17 May 1995 11:12:55 PDT

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IGS Electronic Mail      Wed May 17 11:12:55 PDT 1995      Message Number 0952
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Author: AC Coordinator
Subject: Wk 0790-0794 IGS Final Orbits

Subject: Wk 0790-0794 IGS Final Orb.

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IGS Final orbits/clocks completed and put onto CDDIS (Weeks 790 - 794)
                                                     (Feb. 26 - Apr. 01, 1995)
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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 )
The EOP were corrected for the difference between the IERS pole series 
and ITRF as published in the IERS 1993 Annual Report (p. II-19, Table II-3),
so both the IGS orbits and the associated ERP files are consistent with ITRF93
(current epoch).

We have downloaded all the 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 the same
except for the orientation difference (Bull.A and Bull.B). Orbit evaluation are
also nearly the same, since we used centre specific ERP in the 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, 28). This should result in more realistic and objective clock
weighting than employed before, provided that the non-SA satellites are
representatives of centre clock solution quality. Starting with the GPS
week 756 the new IGS erp format (see IGSMAIL# 662) is used by all Analysis
Centres and for the IGS erp files. ERP rates, whenever given, are also utilized
in both orbit combination and the long arc evaluation.

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:

IGS07900-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0790
IGS07910-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0791
IGS07920-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0792
IGS07930-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0793
IGS07940-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0794

IGS07907.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS07917.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS07927.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS07937.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS07947.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)

IGS07907.SUM    Complete summary/statistics report
IGS07917.SUM    Complete summary/statistics report
IGS07927.SUM    Complete summary/statistics report
IGS07937.SUM    Complete summary/statistics report
IGS07947.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)

IGR07900-6.SP3   Rapid service orbits/clocks for days 0-6, week 0790
IGR07910-6.SP3   Rapid service orbits/clocks for days 0-6, week 0791
IGR07920-6.SP3   Rapid service orbits/clocks for days 0-6, week 0792
IGR07930-6.SP3   Rapid service orbits/clocks for days 0-6, week 0793
IGR07940-6.SP3   Rapid service orbits/clocks for days 0-6, week 0794

IGR07907.ERP     Rapid service EOP associated with the above orbits (Bull A)
IGR07917.ERP     Rapid service EOP associated with the above orbits (Bull A)
IGR07927.ERP     Rapid service EOP associated with the above orbits (Bull A)
IGR07937.ERP     Rapid service EOP associated with the above orbits (Bull A)
IGR07947.ERP     Rapid service EOP associated with the above orbits (Bull A)

IGR07907.SUM     Rapid service complete summary/statistic report 
IGR07917.SUM     Rapid service complete summary/statistic report 
IGR07927.SUM     Rapid service complete summary/statistic report 
IGR07937.SUM     Rapid service complete summary/statistic report 
IGR07947.SUM     Rapid service complete summary/statistic report 

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REMARKS/CORRECTIONS:

The following table shows the average statistics of the Final Orbit/clock 
combination for the current five weeks (0790-0794).

Start: 95 Feb / wk790
End:   95 Apr / wk794

     STA  DX    DY    DZ     RX     RY     RZ   SCL  RMS  WRMS LaRMS  RMSc  Days
    ----------------------------------------------------------------------------
cod  52  0.00  0.00  0.00  -0.49   0.19   0.22  0.0   11    8   15   398.3   35
         0.01  0.01  0.01   0.20   0.20   0.23  0.2
emr  25  0.01 -0.02  0.01  -0.19  -0.02   0.03 -0.2   11   11   17     1.1   35
         0.01  0.01  0.01   0.24   0.29   0.18  0.1
esa  37  0.01 -0.01 -0.03   0.36   0.42  -0.11  0.1   17   15   20     5.9   35
         0.01  0.01  0.01   0.30   0.41   0.36  0.1
gfz  42 -0.03 -0.01  0.01  -0.21   0.27  -0.10 -0.3   11   10   17     7.8   35
         0.01  0.01  0.01   0.15   0.27   0.18  0.1
jpl  32  0.01  0.04  0.00  -0.56   0.18   0.19  0.0   10   10   13     1.3   35
         0.01  0.01  0.01   0.23   0.29   0.18  0.1
ngs  36  0.01 -0.01 -0.01  -0.47   0.64  -0.30  0.7   23   22   24 13002.5   35
         0.01  0.02  0.02   0.38   0.38   0.26  0.4
sio  37  0.01 -0.02 -0.01   0.81  -0.34  -0.40  0.3   24   21   24     0.0   35
         0.01  0.02  0.05   0.58   0.58   1.33  0.2

     Units: m   - DX, DY, DZ, RMS, WRMS, LaRMS (Long arc orbit RMS)
            mas - RX,RY,RZ
            ppb - SCL
            ns  - RMSc (sv clock)

The following table shows the average statistics of the Final Orbit/clock 
combination for the current year (1995, weeks 0782-0794).

Start: 95 Jan / wk782
End:   95 Apr / wk794

     STA  DX    DY    DZ     RX     RY     RZ   SCL  RMS  WRMS LaRMS  RMSc  Days
    ----------------------------------------------------------------------------
cod  50  0.00  0.00  0.00  -0.38   0.12   0.10  0.0   11    9   13   290.4   91
         0.01  0.01  0.01   0.26   0.28   0.24  0.1
emr  24  0.01 -0.02 -0.01  -0.02  -0.06   0.03 -0.2   12   12   16     1.0   91
         0.01  0.01  0.02   0.40   0.35   0.18  0.2
esa  32  0.00 -0.01 -0.02   0.02   0.20  -0.08  0.1   18   15   18     4.7   91
         0.01  0.01  0.01   0.49   0.50   0.37  0.2
gfz  40 -0.03 -0.01  0.01  -0.28   0.18  -0.14 -0.3   12   11   16     7.0   91
         0.01  0.01  0.01   0.21   0.27   0.18  0.2
jpl  32  0.01  0.05  0.00  -0.49   0.11   0.09  0.1   10   10   11     1.1   91
         0.01  0.01  0.01   0.26   0.31   0.18  0.2
ngs  35  0.02 -0.02 -0.01  -0.40   0.46   0.00  0.7   22   22   23  9163.1   91
         0.02  0.02  0.02   0.37   0.38   0.40  0.3
sio  35  0.02 -0.04  0.05   0.40   0.05  -0.89  0.1   24   21   24     0.0   91
         0.02  0.03  0.09   0.62   0.69   2.26  0.3

     Units: m   - DX, DY, DZ, RMS, WRMS, LaRMS (Long arc orbit RMS)
            mas - RX,RY,RZ
            ppb - SCL
            ns  - RMSc (sv clock)

[Mailed From: Jan Kouba <[email-masked]>]