[IGSMAIL-6812] Fwd: [IGSCB-31316] IGS timescales

[Robert Khachikyan]

A message from Ken Seinor.


-------- Original Message --------

All,

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.

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.

Best regards,

Ken Senior


	

	

*  Ken L. Senior*
   Advanced Space PNT
   Naval Center for Space Technology


	
	

	

Naval Research Laboratory

4555 Overlook Ave SW

Washington, D.C. 20375

www.nrl.navy.mil

	

TEL:

	

202-767-2043

ALT:

	

202-279-4426

Secure:

	

843-4426

FAX:

	

202-767-2845

E-MAIL:

	

ken.senior at nrl.navy.mil <mailto:ken.senior at nrl.navy.mil>



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