| Date: | 1998-08-31 14:00:00 | |
| Sender: | John J. Degnan <slrmail (EDC)> | |
| Subject: | [SLR-Mail] No. 149: IGEX98 GLONASS Tracking Campaign | |
| Author: | John J. Degnan | |
| Content: | ******************************************************************************** SLR Electronic Mail 1998-08-31 14:00:00 UTC Message No. 149 ******************************************************************************** Author: John J. Degnan Subject: IGEX98 GLONASS Tracking Campaign I am forwarding to you a request from the IGEX98 Steering Committee as represented by the group´s SLR liaison, Werner Gurtner, for all SLR stations to take part in an international GLONASS tracking campaign for a period of three months, beginning September 20, 1998 and ending December 20, 1998. The IGEX98 campaign has the backing of CSTG, IGS, and ION and was tentatively approved by the April 1998 CSTG SLR/LLR Subcommission General Assembly in Nice pending receipt of (1) the official request from the IGEX98 Steering Committee, (2) permission by the spacecraft owners (Missiuon Control center in Moscow) to track the additional satellites, and (3) adequate involvement of the SLR analysis community in the computation of GLONASS orbits. All of these requirements have been met, and I therefore ask, on behalf of the CSTG SLR/LLR Subcommission Steering Committee, that the global SLR network support this campaign to the best of its ability. Specifically, for the period of this campaign, the GLONASS satellites listed in the attached IGEX98 announcement will be assigned a higher CSTG tracking priority than the GPS-35 and GPS-36 satellites. We will revert to the original priority structure on December 21, 1998. Thank you in advance for your support. Sincerely, John J. Degnan Chairperson CSTG Satellite and Lunar Laser Ranging Subcommission IGEX98 GPS/GLONASS Campaign: Request for SLR Tracking ***************************************************** IGEX98 Steering Committe >From September 20, 1998 till December 20, 1998 CSTG, IGS, and ION organize the first worldwide combined GPS/GLONASS (radiowave) tracking campaign. Goals, organizational details and the Call for Participation can be found on two web sites at http://lareg.ensg.ign.fr/IGEX and http://www.ion.org/workgroup.html The campaign has been presented to the SLR community at the CSTG/SLR meeting in Nice in April 1998. One of the primary goals of the campaign is the development of the physical models for precise orbit determination by means of radiowave observations. An independent check of these orbits can be done by SLR tracking. The question will also be raised to what extent SLR tracking can improve the overall orbit quality, depending e.g. on the tracking density. Because SLR tracking of GLONASS satellites is much easier than GPS and because _all_ GLONASS satellites are equipped with corner cubes, the influence of SLR observations on combined orbit determination may be much more important than with GPS. On the other hand, if GLONASS will eventually be combined in the analysis with GPS, the influence of SLR might extend to GPS, as well. Consequently the Steering Committee of the IGEX98 campaign asks the global SLR network to extend their tracking to a larger number of GLONASS satellites during the IGEX98 campaign and to downgrade the priority of GPS satellites for this period, if necessary. IRVs will be generated for all active GLONASS satellites by RGO based on orbit predictions by CODE computed from broadcast orbital elements. See separate SLRMail to be issued shortly by RGO. Tracking of all satellites might be useful. However, in order to not overload the SLR tracking network the IGEX98 Steering Committee does not ask for the tracking of all satellites but limits the request to the follwing 9 satellites, 3 per plane, out of which 3 satellites are already been tracked by (some) SLR stations: Slot Plane SLR name Cospar Currently number Number tracked by SLR 3 1 Glonass 68 9407601 4 1 Glonass 70 9407603 6 1 Glonass 69 9407602 9 2 Glonass 79 9506803 12 2 Glonass 65 9405001 yes 16 2 Glonass 66 9405002 yes 17 3 Glonass 62 9402101 20 3 Glonass 71 9500901 yes 22 3 Glonass 72 9500902 Glonass 67, which is at present tracked by the SLR network, is excluded from this list, as its official status is ”unusable”. Its tracking is probably serving no useful purpose. A full coverage of the passes is not necessary, 5-15 minutes (1-3 Normal Points) around start, middle and end of the pass should be adequate. The authorities of the Russian Space Agency have granted the permission to track all GLONASS satellites by SLR (E-mail from August 10, 1998). Thank you very much for your cooperation. We are looking forward to a fruitful collaboration during and hopefully also after the IGEX campaign. For the IGEX98 Steering Committee Werner Gurtner SLR Liaison -------------------- . . -- -------------- /------------------------ EUROLAS Data Center ( ) ( ) ***_ ^ -o- Tel. +49 89 23031-109 EDC c/o DGFI | | | | *|* o|_ / / / Fax: +49 89 23031-240 Marstallplatz 8 |o| |o| |o |_) / / email: D-80539 Muenchen | |/| | |___| / edc@dgfi.badw-muenchen.de ------------------------------------------------------------------------------- From: slrmail (EDC) ******************************************************************************** |