From jimr@maia.usno.navy.mil Tue Jun 15 15:50:01 EDT 1999
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From: Jim Ray (USNO 202-762-1444) 
Message-Id: <199906151947.PAA23402@maia.usno.navy.mil>
Subject: mod to clock file format
To: gpst@maia.usno.navy.mil
Date: Tue, 15 Jun 1999 15:47:22 EDT
X-Mailer: Elm [revision: 212.4]
Status: RO

Based on discussions at the IGS Analysis Center Workshop, held last week
at Scripps Institute of Oceanography, Analysis Centers were asked to
include station coordinates in their clock solution files.  These
coordinates should correspond to the values used in the clock analysis
(whether fixed or adjusted).  This will be a great convenience for users
of these files.

This change can be accomodated in the existing "SOLN STA NAME / NUM" header
record by using 35 previously blank spaces (for stations on or near the
Earth's surface).  Note that the geocentric coordinates should be given in
millimeter units.  The relevant portion of the changed format is:

 +--------------------+------------------------------------------+------------+
 |SOLN STA NAME / NUM | For each station/receiver included in    |            |
 |                    | the clock data records, as well as the   |            |
 |                    | analysis reference clock even if it has  |            |
 |                    | zero values and is not included in the   |            |
 |                    | data records (number given in the        |            |
 |                    | previous header record), include one     |            |
 |                    | record with the following information:   |            |
 |                    | - 4-character station/receiver name      |   A4,1X,   |
 |                    |   designator                             |            |
 |                    | - Unique station/receiver identifier,    |    A20,    |
 |                    |   preferably the DOMES number for        |            |
 |                    |   fixed stations                         |            |
 |                    | - Geocentric XYZ station coordinates     |   I11,X,   |
 |                    |   corresponding to the analysis clock    |   I11,X,   |
 |                    |   values reported (in millimeters!)      |    I11     |
 |                    |                                          |            |
 |                    | * REQUIRED for data types "Ax"           |            |
 |                    |                                          |            |
 +--------------------+------------------------------------------+------------+

An example of such a record would look like:

GOLD 40405S031           -1234567890 -1234567890 -1234567890SOLN STA NAME / NUM

----|---1|0---|---2|0---|---3|0---|---4|0---|---5|0---|---6|0---|---7|0---|---8|


Earlier this month, clarifications were added to deal with reporting
analysis clock reference values when the time scale has been re-aligned.

All these changes are backwards compatible.  The complete documentation
is available at http://maia.usno.navy.mil/gpst/clock-format .

--Jim