Subject: [IGSMAIL-1236] Wk 0834-7 IGS Final Orbits
From: AC Coordinator
Date: Mon, 4 Mar 1996 8:47:29 PST

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IGS Electronic Mail      Mon Mar  4  8:47:29 PST 1996      Message Number 1236
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Author: AC Coordinator
Subject: Wk 0834-7 IGS Final Orbits

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IGS Final orbits/clocks completed and put onto CDDIS (Weeks 834 - 837)
                                                     (Dec 31/95 Jan 27, 1996)
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    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:

IGS08340-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0834
IGS08350-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0835
IGS08360-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0836
IGS08370-6.SP3   IGS GPS orbit/clock files for days 0-6, week 0837

IGS08347.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS08357.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS08367.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)
IGS08377.ERP    EOP associated with the above orbits (Bull. B aligned to ITRF)

IGS08347.SUM    Complete summary/statistics report
IGS08357.SUM    Complete summary/statistics report
IGS08367.SUM    Complete summary/statistics report
IGS08377.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)

IGR08340-6.SP3   Rapid service orbits/clocks for days 0-6, week 0834
IGR08350-6.SP3   Rapid service orbits/clocks for days 0-6, week 0835
IGR08360-6.SP3   Rapid service orbits/clocks for days 0-6, week 0836
IGR08370-6.SP3   Rapid service orbits/clocks for days 0-6, week 0837

IGR08347.ERP     IGS Mean EOP associated with the above orbits 
IGR08357.ERP     IGS Mean EOP associated with the above orbits
IGR08367.ERP     IGS Mean EOP associated with the above orbits
IGR08377.ERP     IGS Mean EOP associated with the above orbits

IGR08347.SUM     Rapid service complete summary/statistic report 
IGR08357.SUM     Rapid service complete summary/statistic report 
IGR08367.SUM     Rapid service complete summary/statistic report 
IGR08377.SUM     Rapid service complete summary/statistic report 

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REMARKS/CORRECTIONS:

            ************* NOTE: ***************************
Since Wk803 the IGS Rapid combinations are performed directly in the 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 
at the beginning and the end of the week.
            ***********************************************

The following table shows the average statistics of the Final orbit/clock 
combination for the current period (Wks 0834-0837).

Start: 95 Dec 31 / wk834
End:   96 Jan 27 / wk837

     STA  DX    DY    DZ     RX     RY     RZ   SCL  RMS  WRMS LaRMS  RMSc  Days
    ----------------------------------------------------------------------------
cod  62  0.00  0.03  0.00  -0.34  -0.03  -0.23  0.1    7    7    9     2.0   28
         0.01  0.01  0.01   0.25   0.25   0.19  0.1
emr  28  0.01 -0.03 -0.01   0.14  -0.12   0.33 -0.1   10   10   14     1.0   28
         0.01  0.01  0.01   0.18   0.19   0.16  0.1
esa  44  0.00 -0.03 -0.02   0.17   0.21  -0.12  0.1   16   14   16     9.6   28
         0.01  0.01  0.02   0.30   0.32   0.42  0.2
gfz  43 -0.03 -0.02  0.00  -0.07  -0.07  -0.13 -0.3   12   11   14     7.2   28
         0.01  0.01  0.01   0.14   0.14   0.19  0.1
jpl  37  0.01  0.03  0.00  -0.43   0.02   0.06  0.2    8    8    9     1.0   28
         0.01  0.01  0.01   0.14   0.21   0.13  0.1
ngs  44  0.01 -0.02  0.01  -0.03   0.46   0.11 -0.1  527  368   16  8366.0   28
         0.01  0.01  0.02   0.21   0.30   0.22  0.2
sio 106 -0.01  0.05  0.02  -0.40   0.02   5.70  0.2 1839 1713   11     0.0   28
         0.01  0.10  0.01   0.46   0.45  29.11  0.1

     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 0782-0837).

Start: 95 Jan 01 / wk782
End:   96 Jan 27 / wk837

     STA  DX    DY    DZ     RX     RY     RZ   SCL  RMS  WRMS LaRMS  RMSc  Days
    ----------------------------------------------------------------------------
cod  57  0.00  0.02  0.00  -0.39  -0.05  -0.02  0.0    9    8   11  3588.0  392
         0.01  0.01  0.01   0.24   0.29   0.23  0.1
emr  26  0.01 -0.02  0.00  -0.02  -0.07   0.13 -0.1   10   10   15     1.0  392
         0.01  0.01  0.01   0.38   0.31   0.19  0.1
esa  41  0.00 -0.01 -0.03   0.29   0.14  -0.01  0.1  377   14   18    24.3  392
         0.01  0.01  0.01   0.42   0.40   0.37  0.2
gfz  44 -0.03 -0.01  0.00  -0.20   0.10  -0.20 -0.3   37   37   15  1829.1  392
         0.01  0.01  0.01   0.20   0.25   0.19  0.1
jpl  34  0.01  0.04  0.00  -0.48   0.04   0.10  0.1    9    9   10     0.9  392
         0.01  0.01  0.01   0.24   0.27   0.15  0.1
ngs  39  0.01 -0.02 -0.01  -0.29   0.29   0.00  0.3  142  100   20 12807.0  392
         0.01  0.02  0.02   0.38   0.40   0.34  0.4
sio  59  0.00 -0.04  0.03   0.01  -0.13   0.17  0.1 3822 2585   20     0.0  392
         0.02  0.05  0.06   0.61   0.64   7.99  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)

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