| Date: | 2005-07-12 00:02:00 | |
| Sender: | Mike Pearlman/Director, ILRS Central Bureau <Carey Noll <carey.noll@nasa.gov>> | |
| Subject: | [SLR-Mail] No. 1343: Special CONT05 Campaign - First Notice | |
| Author: | Mike Pearlman | |
| Content: | ******************************************************************************** SLR Electronic Mail 2005-07-12 00:02:00 UTC Message No. 1343 ******************************************************************************** Author: Mike Pearlman/Director, ILRS Central Bureau Subject: Special CONT05 Campaign - First Notice To: ILRS Stations All of the the Space Geodesy Services including the ILRS will be participating in a special data acquisition campaign CONT05 (CONTinuous tracking 05) during the period September 12 - 27. The CONT campaigns were originally organized by the VLBI community, but they are now being expanded under the International Earth Rotation and Reference Systems Service (IERS) to include all of the space geodesy techniques. SLR, GPS, VLBI, and DORIS will all be taking intensive data that can then be analyzed in combination and comparison studies. We know that the combination of techniques gives the best measurement results and campaigns such CONT05 will give us an opportunity to try new ways of combining the data. The VLBI stations will be taking continuous data over the period September 12 - 27. The GPS network will focus on data acquisition at sites with colocated techniques. The DORIS network will place special emphasis on sites with colocated techniques and on satellites with multitracking techniques. (DORIS plus GPS and or SLR). SLR CAMPAIGN SLR will focus on two areas: 1. Tracking on GPS and GLONASS. There are unexplained differences of a few centimeters between the radio and SLR measurements being taken on both GPS and GLONASS. More intensive SLR tracking on these satellites will allow us to study and hopefully resolve the differences between the radio and optical systems. Ranging to GPS and GLONASS is also a means of gaining some operational experience in preparation for the Galileo satellite complex which is scheduled for launch starting late this year. In all, 30 Galileo satellites will be calling on SLR support at various times for calibration and validation. These satelites will be at an altitude of 23,000 km with SLR links comparible to GPS and GLONASS. We need to improve our ranging techniques, if we are going to provide robust support. Historically, SLR data yield in GPS and GLONASS has been weak. This is a chance to try to do better. Ideally we would like a few normal points at the beginning, in the middle, and at the end of a pass. Do the best you can. Some stations will have nightime opportunities on GPS. Most stations will have nightime opportunities on the GLONASS satellites. During the periods when there is nightime visibility at your station, the priority of Glonass and GPS will be elevated above that of LAGEOS. Please make every effort during the campaign to get data during days with visibilities. Our current plan is to start this activity on September 1 and run it through September 28 to increase the number of opportunities. We invite stations that have the capability to range in daylight to GPS and GLONASS to do so. We will issue schedule information to the visibilities for GPS and GLONASS for the network stations. 2. Tracking on multitechnique satellites. Several satellites have at least one tracking technique in addition to SLR - GRACE (GPS), Envisat (DORIS), Jason - 1 (GPS and DORIS). The most accurate orbits that the we have achieved so far are through combination of data types. During the CONT05 Campaign, the normal high priority tracking on these satellites should be sufficient, but please make every effort to track as many passes as possible to give us a very robust data set. Any effort that you can make to augment the station crew or extend the operating hours wil be very beneficial. SPECIAL PROCEDURES In order to the make this work, we need everyone´s cooperation. We ask that the network stations avoid scheduling of upgrading or elective maintenance during the September period. We need to the network to be at full capability during this campaign period. If work needs to be done at your station, try to schedule it before the campaign. With everyone´s cooperation, we can make this campaign a great success. Regards, Mike Dr. Michael R. Pearlman Harvard-Smithsonian Center for Astrophysics 60 Garden St. Cambridge MA 02138 tel. (617) 495-7481 fax. (617) 496-0121 e-mail. mpearlman@cfa.harvard.edu From: Carey Noll ******************************************************************************** |