Subject: FW: Biases in SLR data due to Stanford event timer non-linearities
From: "Frank G. Lemoine" <[email-masked]>
To: <[email-masked]>
Date: Wed, 07 Feb 2007 15:51:49 +0000

Dear DORIS colleagues

Although this forum pertains to DORIS issues, I forward below a memo from
 Erricos and compiled by Graham Applby regarding the issue of the Stanford
 Event Timers in the global SLR network. This impacts joint analysis
 of SLR & DORIS data.

Regards,

Frank Lemoine
------ Forwarded Message
From: "Erricos C. Pavlis" <[email-masked]>
Date: Wed, 10 Jan 2007 17:46:34 -0500
To: ILRS Analysis Working Group <[email-masked]>, ILRS Analysis
Centers <[email-masked]>, ILRS Associate Analysis Centers
<[email-masked]>
Cc: carey Noll <[email-masked]>
Subject: Biases in SLR data due to Stanford event timer non-linearities
Resent-From: Carey Noll <[email-masked]>
Resent-To: [email-masked],
[email-masked], [email-masked]
Resent-Date: Thu, 11 Jan 2007 08:43:27 -0500

Dear colleagues,

On Monday I sent you a message with the corrections to be applied to
the SLR data collected at Herstmonceux according to the investigation
carried out by Graham and colleagues at the station. As you all know,
Graham has also produced a table with best estimates for the
corresponding errors at other SLR sites with similar equipment (sent
out in December 2006).

Their results, in a simplified form, are attached below focusing on
the correction (in millimeters !) that should be applied to the
LAGEOS ranges from these stations and over the period that is given
in the table. Please note that the 7 mm shown here for Herstmonceux
is only part of the total correction that we are to apply (8.5 mm),
the additional 1.5 mm coming from a different error source, a filter
in the optical path during calibration ranging, which was not used
during satellite ranging. Please do not be confused by the two
different numbers! The 8.5 mm is the number that we should correct-
for the Herstmonceux data.

I would like to ask you that during the current reprocessing, please
consider including the corrections that are provided for all other
"core" stations below, and for the remaining sites, it is up to you
if you want to apply the corrections AND solve for a bias OR simply
solve for a bias.

Good luck!

ecp

   +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
   Dr. Erricos C. Pavlis                       Phone:    +1 (410)
455-5832
   Research Associate Professor         FAX:    +1 (410) 455-5868
                                                       EU Mobile:
+30-694-241-5079
   Chair, ILRS Analysis Working Group

   Joint Center for Earth Systems Technology, (JCET/UMBC)
   University of Maryland Baltimore County & NASA Goddard
   Academic IV  Wing A  Suite 114E
   1000 Hilltop Circle
   Baltimore, Maryland
   U S A    21250  
[email-masked]

   +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

------ End of Forwarded Message

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