| Date: | 2015-06-11 08:18:07 | |
| Sender: | ”SLR station ”Katzively-1893” <clogao@rambler.ru> | |
| Subject: | [SLR-Mail] No.2319: LightSail-A satellite | |
| Author: | Andriy Makeyev | |
| Content: | Author: Andriy Makeyev Dear colleagues, LightSail-A is the satellite listed as #1 in current ILRS priority list since Jun 08 (http://ilrs.gsfc.nasa.gov/missions/mission_operations/priorities/index.html). Because of its shape, high atmospheric drag caused by high area to mass ratio, and low perigee of the satellite´s orbit it is going to decay as soon as Jun 14 near 19 h UTC (±18 h), according to latest analysis by amateur astronomer Ted Molczan, published on site http://www.satobs.org/LightSail-A.html The most up-to-date predictions in TLE format are also available on that site. GIT that provides CPFs derives them either from that site or from JSpOC-provided TLEs through CalPoly that are updated not so often (http://mstl.atl.calpoly.edu/~ops/ultrasat/ultrasat_jspoc.txt) Predictions tend to be unprecise: it is even hard to catch the sat into telescope´s field of view. Our SLR station tried to perform laser ranging last night and found it out of the FOV on the second pass. Laser ranging was unsuccessfull (no echoes received in 100 mcs window). So, LightSail-A (lightsail1) tends to be a very hard target for ILRS network. Could anyone propose better model then SGP4 to CPF provider (Sean Chait, schait3@gatech.edu)? Also, if observations were made, maybe it would be useful to inform Sean about best element set, that corresponds to observed pass, and time bias? Or share positional observations? Best regards, Andriy Makeyev Chief engineer of the SLR station ”Katzively-1893” |