Subject: [IGSMAIL-1034] Wk 0803-807 IGS Final Orb.
From: AC Coordinator
Date: Fri, 4 Aug 1995 12:31:36 PDT

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IGS Electronic Mail      Fri Aug  4 12:31:36 PDT 1995      Message Number 1034
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Author: AC Coordinator
Subject: Wk 0803-807 IGS Final Orb.

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IGS Final orbits/clocks completed and put onto CDDIS (Weeks 803 - 807)
                                                     (May 28 - July 1, 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 (IGS mean pole 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:

IGS08030-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0803
IGS08040-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0804
IGS08050-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0805
IGS08060-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0806
IGS08070-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0807

IGS08037.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS08047.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS08057.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS08067.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS08077.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)

IGS08037.SUM    Complete summary/statistics report
IGS08047.SUM    Complete summary/statistics report
IGS08057.SUM    Complete summary/statistics report
IGS08067.SUM    Complete summary/statistics report
IGS08077.SUM    Complete summary/statistics report

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

IGR08030-6.SP3   Rapid service orbits/clocks for days 0-6, week 0803
IGR08040-6.SP3   Rapid service orbits/clocks for days 0-6, week 0804
IGR08050-6.SP3   Rapid service orbits/clocks for days 0-6, week 0805
IGR08060-6.SP3   Rapid service orbits/clocks for days 0-6, week 0806
IGR08070-6.SP3   Rapid service orbits/clocks for days 0-6, week 0807

IGR08037.ERP     IGS Mean EOP associated with the above orbits 
IGR08047.ERP     IGS Mean EOP associated with the above orbits
IGR08057.ERP     IGS Mean EOP associated with the above orbits
IGR08067.ERP     IGS Mean EOP associated with the above orbits
IGR08077.ERP     IGS Mean EOP associated with the above orbits

IGR08037.SUM     Rapid service complete summary/statistic report 
IGR08047.SUM     Rapid service complete summary/statistic report 
IGR08057.SUM     Rapid service complete summary/statistic report 
IGR08067.SUM     Rapid service complete summary/statistic report 
IGR08077.SUM     Rapid service complete summary/statistic report 

 *****************************************************************************

REMARKS/CORRECTIONS:
            ************* NOTE: ***************************
-Since Wk 803 the IGS Rapid combinations are performed directly in ITRF frame, 
without any EOP alignments. The associated erp files (IGR0WWW7.erp) contain
weighted avaverages of all submitted erp solutions given at 12h UT each day
(using the orbit weights), augmented with the current IERS Bull.A UT1-UTC.
Consequently, since Wk 803, the IGR erp contain 7 daily EOP values at 12h UT,
unlike the Final orbit erp (and the Rapid orbit erp prior Wk 803) which
contain 9 daily IERS EOP values at 0h UT to facilitate accurate interpolation 
during the whole week period.
            ***********************************************

The following table shows the average statistics of the Final Orbit/clock 
combination for the current period (Wks 0803-0807).

Start: 95 May 28 / wk803
End:   95 Jul 01 / wk807

     STA  DX    DY    DZ     RX     RY     RZ   SCL  RMS  WRMS LaRMS  RMSc  Days
    ----------------------------------------------------------------------------
cod  57  0.00  0.03  0.00  -0.52  -0.09   0.00  0.0   11    8   13  1892.5   35
         0.01  0.01  0.01   0.22   0.20   0.15  0.1
emr  26  0.01 -0.02  0.00  -0.30  -0.14   0.16 -0.1    9    9   16     0.9   35
         0.01  0.01  0.01   0.32   0.26   0.16  0.1
esa  36  0.00 -0.01 -0.02   0.54   0.16   0.08  0.1   18   16   19    35.0   35
         0.01  0.01  0.01   0.34   0.32   0.41  0.1
gfz  44 -0.04 -0.01 -0.01  -0.21   0.26  -0.32 -0.3   11   11   17    11.8   35
         0.01  0.01  0.01   0.13   0.16   0.14  0.1
jpl  34  0.01  0.05  0.01  -0.59   0.05   0.18  0.2   10   10   12     0.9   35
         0.01  0.01  0.01   0.21   0.22   0.15  0.1
ngs  37  0.01 -0.05 -0.02  -0.35   0.23   0.00  0.4   20   19   21  2094.0   35
         0.02  0.01  0.02   0.45   0.31   0.36  0.3
sio  34  0.00 -0.08  0.04   0.41  -0.34  -0.25  0.2   25   22   25     0.0   35
         0.02  0.02  0.05   0.59   0.55   3.95  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 since Jan. 1/95 (Wks 0782-0807).

Start: 95 Jan 01 / wk782
End:   95 Jul 01 / wk807

     STA  DX    DY    DZ     RX     RY     RZ   SCL  RMS  WRMS LaRMS  RMSc  Days
    ----------------------------------------------------------------------------
cod  53  0.00  0.01  0.00  -0.46   0.05   0.09  0.0   11    9   13  5271.8  182
         0.01  0.01  0.01   0.25   0.31   0.21  0.1
emr  25  0.01 -0.02  0.00  -0.18  -0.08   0.09 -0.2   11   11   15     1.0  182
         0.01  0.01  0.01   0.38   0.33   0.20  0.2
esa  34  0.00 -0.01 -0.03   0.25   0.19   0.00  0.1   19   15   20    23.6  182
         0.01  0.01  0.01   0.47   0.44   0.37  0.2
gfz  42 -0.04 -0.01  0.00  -0.27   0.17  -0.22 -0.3   11   11   16    15.0  182
         0.01  0.01  0.01   0.19   0.27   0.19  0.1
jpl  33  0.01  0.05  0.00  -0.54   0.06   0.11  0.1   10   10   11     1.0  182
         0.01  0.01  0.01   0.24   0.30   0.16  0.1
ngs  36  0.01 -0.03 -0.01  -0.37   0.35  -0.01  0.6   21   20   22  8348.4  182
         0.02  0.02  0.02   0.40   0.40   0.38  0.3
sio  34  0.02 -0.06  0.04   0.24  -0.23  -0.54  0.1   23   21   24     0.0  182
         0.02  0.03  0.08   0.62   0.68   2.39  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]>]