I derived the following using data from Ed Cannon, Paul Gabriel and U.S. Spacecom, between 2001 Aug 14 - 17: USA 159 r1 9.8 3.0 0.0 4.8 v 1 26881U 01033B 01229.08166667 .00286333 00000-0 35779-3 0 08 2 26881 28.6540 176.3098 0378059 193.7583 165.2471 15.39571766 00 Mean residuals are about 0.02 deg. I used Paul's preliminary observations. He prefers to hold off posting them to SeeSat-L until he is more certain of their accuracy. Overall, they look pretty good to me, but 2 of his 5 points have somewhat higher residuals than the others, so his caution may prove warranted. I believe that Paul uses the same method that I use when I need/want to obtain many points on a pass: he does not stop after each observation to sketch the reference stars, but relies on memory, perhaps assisted by a tape recorder. To find our reference stars for the purpose of observation reduction, we compute the expected position of the object at the time of each observation, using the best available elements, and look for the stars in an atlas. If the elements are reliable, then the reference stars should be readily identifiable. However, in this case, Paul had only preliminary elements, which may not be sufficiently accurate to unambiguously reveal the correct reference stars, hence his caution about posting his obs. Regarding my data credit to U.S. Spacecom, I refer to their 2nd elset: 1 26881U 0133B 01226.28993968 .00000349 00000-0 62037-5 0 21 2 26881 28.6968 195.6121 0243087 165.2938 177.1552 15.22595359 1228 I agree with Mike McCants that although this elset is largely erroneous, it probably does have some basis in reality. I assumed that this elset is accurate at its epoch, so I generated a fictitious point, looking straight up from the sub-satellite point at the epoch. Ted Molczan ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www2.satellite.eu.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Fri Aug 17 2001 - 10:02:38 PDT