[IGSMAIL-4771]: Timely Rapid and Final GLONASS Orbits Available from CODE Analysi s Center

[Slater, James A.]

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IGS Electronic Mail      19 Dec 08:57:21 PST 2003      Message Number 4771
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Author: Jim Slater

Please disregard this message if you already received it via IGLOSmail.

Since 8 June 2003 (GPS Week 1222), the CODE Analysis Center at the
University of Bern has been computing rapid and final orbit products for the
GLONASS satellites.  CODE generates these GLONASS orbits at the same time as
the GPS rapid and final orbits.  (Reference IGSMail-4474.)  The final CODE
GLONASS orbits are in the same ephemeris file as the GPS final orbits and
are not available separately.  At the NASA CDDIS Data Center, the final
GLONASS orbits from CODE can be found at
ftp://cddisa.gsfc.nasa.gov/pub/gps/products by week number in the files
labeled "codnnnnd.eph.Z" where 'nnnn' is the GPS week no. and 'd' is the day
of the week (0-6).

The GLONASS rapid orbits can be found only at the CODE website at
http://www.aiub.unibe.ch/download/CODE in the files labeled as
"CODnnnnd.EPH_R".  Predicted rapid orbits are in the files labeled as
"CODnnnnd.EPH_P". These rapid orbit files include both GPS and GLONASS
satellites.  Lists of the IGS stations used to compute the final and rapid
GLONASS orbits for each day can be found at
http://www.aiub.unibe.ch/download/igsdata in the files labeled
"glonass_final.txt" and "glonass_rapid.txt".

The timely availability of the CODE GLONASS orbits should facilitate the use
of the GLONASS data for a number of applications such as time transfer, and
ionospheric and tropospheric modeling.  This is especially relevant due to
the recent launch of three GLONASS satellites, bringing the potential
operational GLONASS constellation to 11 satellites.  BKG, ESA and MCC also
compute GLONASS orbits, but these are generally not available for 3-6 weeks;
and the combined GLONASS orbit product can only be generated after all the
individual analysis centers submit their final orbits.  Only CODE generates
a rapid orbit for the GLONASS satellites and its final orbits do not have
the latency problem associated with the other analysis centers.

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JIM SLATER     (301)227-4549     Fax: (301)227-2837     E-mail:
slaterj at nima.mil
NGA, PPSC, MS D-68, 4600 Sangamore Rd., Bethesda, MD 20816-5003, U.S.A.
"Discovery consists of seeing what everyone else has seen and thinking what
no one else has thought" -Albert Szent-Gyorgi