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A message from Ken Seinor.<br>
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<p class="MsoNormal">All,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The clocks in SVN62/PRN01, SVN63/PRN25, and
SVN66/PRN27 were all given delta drift offsets ranging from a
few to ten parts in 10^19 s/s^2 on 17 July. Because these
satellite clocks are relatively very stable as compared to
other ground clocks they’ve been carrying ~5% weight in the
ensemble (excluding SVN66 which is still subject to rubidium
start-up transient) for both IGRT and IGST. While bad data as
well as most delta maneuvers and delta clock changes are easy
to detect and mitigate automatically in the timescale
algorithm, delta drift changes are much less so. Therefore,
since 17 July the timescales have suffered in stability and in
UTC offset. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">To mitigate these effects in the future and
to correct data since 17 July I’ve implemented the ability to
ingest known delta drift corrections from 2SOPS into the IGS
timescales, including the three satellite deltas on 17 July.
The ACC will soon resubmit the Rapids and Finals since 17 July
to incorporate these corrections and update the relevant Clock
RINEX and SP3 files.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Best regards,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Ken Senior<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b><span
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L. Senior</span></b><span
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<br>
</span><span
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Space PNT<br>
Naval Center for Space Technology</span><span
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<o:p></o:p></span></p>
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