[Files attached to Steve] I prefer AllCola, also by Rob Matson, which runs ALL satellites in one file against all in another (or the same file, and/or from a certain elset in the first file to end-of-file) [My version of] COLA does not seem to be Y2K-ready. I extracted three elsets to Steve.tle; (my) typical input is in Steve.txt, and the result in Steve.col. #20847 is 88.1 km from #25406, its orbit is 84.5 km from (below) 25406 because it is 16.5 degrees from the nadir of 25406 at 8/17/2002 2:59:03.28 UTC. With a partial satbase.tle (from #25406 - steve2.txt) I get the closest encounter: ------------------------------------------ Target satellite: #25615 Name: USA 141 (ATEX) 3.0 0.0 Perigee: 741.40 km Apogee: 757.08 km Velocity at perigee: 7.4866 km/sec Satellites in range: 3 .... 8/18/2002 6:30:48.48 20847 FengYun 1B r K 2.5 7.0/ 4.1 52.7 +2.13 .... I do not know of any program predicting encounters with three or four satellites - I believe there is at least one which can predict appulses of two satellites. SkyMap can do satellite + star, Sun, Moon or planet. My approach for estimating probability is predicting (graphically with SkyMap) # of crossings over a section (say 30 degrees) of the track over a longer time (say 20 minutes), and reduce that number to the 7 seconds or so separating the USA 160 pair. Over one such section/interval near the 50 degree culmination 2002-08-20 22:11:05 local I found 18 crossings of satbase.tle objects predicted brighter than +10. So, for 7 seconds that gives a 10% chance ! Further from culmination the tracks are denser, so the chances are greater, and for a "total" pass of 150 degrees this gives >> 50% ! (correct me if I am wrong) ----- Original Message ----- ... > Close encounters are interesting. Can some one help me with COLA program, I > never have been able to get it to work.I think this program finds close > encounters, not sure. Also what is the probability or is there a way to > predict if another sat would cross in between the visual track of USA 160 A > and C or thru one of the NOSS triplets? ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www.satellite.eu.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Sat Aug 17 2002 - 10:11:14 EDT