| Date: | 1999-05-15 12:37:00 | |
| Sender: | John J. Degnan <> gurtner@ubeclu.unibe.ch (WERNER GURTNER)> | |
| Subject: | [SLR-Mail] No. 313: Revised IGEX-98 Tracking Priorities | |
| Author: | John J. Degnan | |
| Content: | ******************************************************************************** SLR Electronic Mail 1999-05-15 12:37:00 UTC Message No. 313 ******************************************************************************** Author: John J. Degnan Subject: Revised IGEX-98 Tracking Priorities for By majority vote, the ILRS Governing Board has voted to approve a modified IGEX-98 Campaign as outlined below. All ILRS Tracking stations are therefore asked to continue tracking the three GLONASS satellites identified below without interruption. All other GLONASS satellites will be dropped from the official ILRS Tracking Priorities List. The Board decision was based on the attached email from Robert Weber, IGEX Coordinator, and Werner Gurtner, our SLR Liaison to the IGEX Campaign. They have recommended an open-ended but significantly scaled-down version of the original IGEX-98 Campaign. Specifically, they would like the SLR network to track one GLONASS satellite in each of the three orbital planes, i.e. Glonass Slot Plane 70 4 1 72 22 3 79 9 2 They offer solid evidence that the campaign to date has provided useful comparisons of GLONASS orbits derived from both laser ranging and microwave data. This strikes me as a very reasonable request - especially since we have had two GLONASS satellites continually on the schedule in the past. Sincerely, John Degnan >Date: Wed, 12 May 1999 11:01:53 +0100 >From: gurtner@ubeclu.unibe.ch (WERNER GURTNER) >Subject: Extension of GLONASS SLR tracking >To: JJD@ltpmail.gsfc.nasa.gov, MPEARLMAN@cfa.harvard.edu >X-VMS-To: DEGNAN_ >X-VMS-Cc: PEARLMAN_,GURTNER > > IGEX-98 Steering Committee > > > Request for Continued GLONASS Tracking by ILRS > ********************************************** > > Dear Colleagues, > > Within the scope of the IGEX experiment the GLONASS satellite > system has been observed intensively by the microwave techniques > since October 1998. In addition, the ILRS supports this > campaign by performing a large number of tracked passes of the > satellites. As a result several institutions within the IGS > and ILRS were able to calculate precise ephemeris. > Currently these orbit solution are accurate to about +/-20 cm > which has been shown by weekly orbit comparisons. > > On April 17, the preliminary end of the IGEX experiment, most of the single- > frequency receiver sites terminated their operation. > > But nevertheless the number of dual frequency receivers is still large > enough for a successful continuation of the campaign and will even increase > during this year. > > From the point of view of the IGEX Associate Analysis Centers a continued > laser tracking of Glonass satellites would be extremely helpful. > > For instance, this would allow for further studies on the bias in the range > residuals between microwave and laser techniques. Moreover unexplained > rotations around the z-axis between laser and microwave ephemeris solutions > occurring on several days (see extract of the orbit combination statistics > below) may be investigated in more details. > > > Table 2.0982.5 GPS week: 0982 Day: 5 MJD: 51123.0 > ----------------------------------------------------- > CENT STA| DX DY DZ RX RY RZ SCL RMS| > --------|-------------------------------------------| > bkg 21| 0.00 0.01 0.04 0.12 0.03 0.84 -0.5 0.20| > cod 17|-0.01 0.00-0.01 0.20 -0.24 -0.26 -0.8 0.15| > esa 32| 0.01-0.01 0.05 -0.69 0.21 0.85 2.0 0.20| > mcc --|-0.01 0.00-0.03 0.22 0.20 -1.37 0.7 0.29| > ----------------------------------------------------- > > Table 2.0981.6 GPS week: 0981 Day: 6 MJD: 51117.0 > ----------------------------------------------------- > CENT STA| DX DY DZ RX RY RZ SCL RMS| > --------|-------------------------------------------| > bkg 16| 0.01 0.00 0.01 0.07 -0.18 0.95 -1.6 0.24| > cod 17| 0.00 0.01 0.01 0.21 -0.31 0.82 -3.0 0.29| > esa 26| 0.02 0.00 0.07 0.35 -0.08 0.70 0.6 0.24| > mcc --|-0.01 0.00-0.01 -0.09 0.11 -0.21 0.1 0.08| > ----------------------------------------------------- > > > Keeping in mind the tremendous workload of the ILRS stations due to various > active and upcoming satellite missions we propose to continue laser tracking > of a significantly reduced number of GLONASS satellites (1 satellite per > each one of the three planes) until the future structure of a global > GLONASS or hopefully GPS/GLONASS microwave tracking network has been > defined and decided upon. > > > Glonass Slot Plane > > 70 4 1 > 72 22 3 > 79 9 2 > > In addition we would like to encourage the ILRS Analyses Centers to submit > GLONASS orbits either on a regular basis (to be included in the > orbit combination process) or from selected weeks and days (for > studying the above mentioned effects) and to present their results > at the IGEX-98 workshop (Nashville, September 13-14, 1999, see IGEXMail 293). > > > Best regards > > Robert Weber Werner Gurtner > (IGEX - AC-Coordinator) (SLR Liaison) > > Dr. John J. Degnan Head, Geoscience Technology Office Code 920.3 NASA Goddard Space Flight Center Greenbelt, MD 20771 USA Phone: 1-301-614-5860 Fax: 1-301-614-5970 Email: jjd@ltpmail.gsfc.nasa.gov ”The early bird may get the worm, but the second mouse gets the cheese!” [Mailed From: John Degnan ******************************************************************************** |