Subject: [IGSMAIL-0911] Wk 0765-781 IGS orbit update
From: Jan Kouba
Date: Wed, 22 Mar 1995 11:32:29 PST

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IGS Electronic Mail      Wed Mar 22 11:32:29 PST 1995      Message Number 0911
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Author: Jan Kouba
Subject: Wk 0765-781 IGS orbit update

    Dear Colleagues,

    A few weeks ago we've discovered a small mistake in the routine which reads
    the ESA erp files, it mistook the ESA sigmas for the pole rates. The net
    effect was that ESA orbit rms, as shown in the IGS sum files, were slightly
    larger for some weeks, in particular the weeks just prior to Wk 787 when
    this was discovered and corrected. The rms for the other AC's and the IGS
    combined orbits are practically the same and unaffected. This
    bug was in effect from Wk 0765. To be sure, we've reprocessed Wks
    0765-781 and downloaded the new sum and sp3 files into CDDIS. Wks
    0782-785 Final Orbits completed recently are correct, which leaves only Wk
    0786 Rapid Orbits affected by this bug and which will be corrected in early
    April when the Bull. B becomes available.
    
    With the exception of two days of the Wk 0766 (Days 0,1), where, by
    mistake, the Bull. A was used instead of the Bull. B, the remaining IGS
    orbit files are practically identical and no action is required by IGS
    users. The only significant changes are the orbit rms for ESA, in
    particular weeks after 780, when ESA orbit rms improvements are more
    noticeable. The main reason for this resubmission is the correct and
    complete IGS orbit combination statistics.

    We apologize for any inconvenience this might have caused.

    With many greetings,

    Jan Kouba 

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

[Mailed From: Robert Liu <[email-masked]>]