Subject: [IGSMAIL-1110] Wk 0817-820 IGS Final Orb
From: AC Coordinator
Date: Tue, 7 Nov 1995 12:09:21 PST

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IGS Electronic Mail      Tue Nov  7 12:09:21 PST 1995      Message Number 1110
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Author: AC Coordinator
Subject: Wk 0817-820 IGS Final Orb

Subject: Wk 0817-820 IGS Final Orb

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IGS Final orbits/clocks completed and put onto CDDIS (Weeks 817 - 820)
                                                     (Sep 03 - Sep 30, 1995)
*******************************************************************************

    The IGS Rapid Orbits for this period 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.

    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 an objective clock weighting, provided that the non-SA satellites
    are representative 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 a 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:

IGS08170-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0817 
IGS08180-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0818
IGS08190-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0819
IGS08200-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0820

IGS08177.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS08187.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS08197.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS08207.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)

IGS08177.SUM    Complete summary/statistics report
IGS08187.SUM    Complete summary/statistics report
IGS08197.SUM    Complete summary/statistics report
IGS08207.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)

IGR08170-6.SP3   Rapid service orbits/clocks for days 0-6, week 0817
IGR08180-6.SP3   Rapid service orbits/clocks for days 0-6, week 0818
IGR08190-6.SP3   Rapid service orbits/clocks for days 0-6, week 0819
IGR08200-6.SP3   Rapid service orbits/clocks for days 0-6, week 0820

IGR08177.ERP     IGS Mean EOP associated with the above orbits 
IGR08187.ERP     IGS Mean EOP associated with the above orbits
IGR08197.ERP     IGS Mean EOP associated with the above orbits
IGR08207.ERP     IGS Mean EOP associated with the above orbits

IGR08177.SUM     Rapid service complete summary/statistic report 
IGR08187.SUM     Rapid service complete summary/statistic report 
IGR08197.SUM     Rapid service complete summary/statistic report 
IGR08207.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 averages 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 contains 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 
for the whole week period.
            ***********************************************

The following table shows the average statistics of the Final Orbit/clock 
combination for the current period (Wks 0817-0820).

Start: 95 Sep 03 / wk817
End:   95 Sep 30 / wk820

     STA  DX    DY    DZ     RX     RY     RZ   SCL  RMS  WRMS LaRMS  RMSc  Days
    ----------------------------------------------------------------------------
cod  62  0.00  0.03  0.00  -0.32  -0.26  -0.04  0.0    9    8   13    38.5   28
         0.01  0.01  0.01   0.21   0.26   0.13  0.1
emr  28  0.02 -0.02  0.01   0.10  -0.27   0.23 -0.1   10   10   16     1.0   28
         0.01  0.01  0.01   0.34   0.29   0.14  0.1
esa  47  0.00 -0.01 -0.03   0.75  -0.10  -0.22  0.2   16   14   16    38.2   28
         0.01  0.01  0.01   0.38   0.39   0.34  0.2
gfz  46 -0.03 -0.01  0.00  -0.16  -0.05  -0.27 -0.2   11   10   16    88.6   28
         0.01  0.01  0.01   0.20   0.22   0.14  0.1
jpl  34  0.01  0.05  0.00  -0.36  -0.11   0.16  0.1   10   10   12     0.9   28
         0.01  0.01  0.01   0.23   0.26   0.15  0.1
ngs  42  0.01 -0.01  0.00  -0.36  -0.02  -0.03 -0.1   13   12   18  3437.4   28
         0.01  0.01  0.01   0.29   0.33   0.24  0.1
sio  97 -0.01 -0.05  0.01   0.10   0.18  -0.15  0.1   11   10   19     0.0   28
         0.02  0.01  0.02   1.00   1.29   0.48  0.2

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

The following table shows the average statistics of the Final Orbit/clock 
combination for the current year (Wks 0782-0820).

Start: 95 Jan 01 / wk782
End:   95 Sep 30 / wk820

     STA  DX    DY    DZ     RX     RY     RZ   SCL  RMS  WRMS LaRMS  RMSc  Days
    ----------------------------------------------------------------------------
cod  55  0.00  0.02  0.00  -0.44  -0.03   0.05  0.0   10    9   12  4301.9  273
         0.01  0.02  0.01   0.23   0.31   0.20  0.1
emr  26  0.01 -0.02  0.00  -0.11  -0.08   0.14 -0.1   10   10   15     1.0  273
         0.01  0.01  0.01   0.36   0.32   0.19  0.2
esa  38  0.00 -0.01 -0.03   0.31   0.14  -0.06  0.1  451   15   19    27.4  273
         0.01  0.01  0.01   0.44   0.41   0.36  0.2
gfz  43 -0.03 -0.01  0.00  -0.23   0.14  -0.22 -0.3   44   44   15    31.2  273
         0.01  0.01  0.01   0.20   0.26   0.18  0.1
jpl  33  0.01  0.05  0.00  -0.50   0.05   0.12  0.1   10   10   10     0.9  273
         0.01  0.01  0.01   0.25   0.29   0.15  0.1
ngs  37  0.01 -0.03 -0.01  -0.35   0.26  -0.06  0.4   20   19   21  7437.3  273
         0.02  0.02  0.02   0.38   0.42   0.37  0.4
sio  43  0.01 -0.06  0.03   0.15  -0.19  -0.31  0.1 4542 3049   22     0.0  273
         0.02  0.03  0.07   0.64   0.71   2.04  0.3

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

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