Very timely observations over a 43 h period, by Tony Beresford, Russell Eberst, Paul Gabriel and Steve Newcomb have captured two manoeuvres by 03054A, to match the mean motion of 03054C, freezing (for now) their time separation at 11.3 s. The situation with 03054A's orbit was extremely confusing after Steve and Paul's obs on consecutive passes last night. Steve's points, added to Russell's pair of Dec 29, yielded the first accurate mean motion after the manoeuvre that preceded Russell's obs: Observation arc 2003 Dec 29.72 - 30.99 UTC: NOSS 3-2 (A) 0.0 0.0 0.0 4.9 v 1 28095U 03054A 03364.96445584 .00000058 00000-0 10000-3 0 07 2 28095 63.4304 230.9972 0124883 178.7269 181.4098 13.40517420 02 WRMS residuals = 0.022 deg Paul's single 03054A point one rev later, was about 0.5 s early relative the above orbit? Had it manoeuvred in the interim? Had Paul reduced the wrong star pair? I actually found a an alternative star pair, that was in excellent agreement with the above orbit. Meanwhile, Steve and Paul's obs were in agreement on 03054C, which still had not manoeuvred: Observation arc 2003 Dec 17.78 - 31.07 UTC: NOSS 3-2 (C) 0.0 0.0 0.0 4.9 v 1 28097U 03054C 03365.03918108 .00000028 00000-0 49374-4 0 09 2 28097 63.4365 230.9936 0127120 180.2910 179.8061 13.40601359 05 WRMS residuals = 0.019 deg Before posting any orbits, I decided to await either a credible referee observation of 03054A, or Paul's confirmation of his reference stars. Tony's observations, more than 11 hours later, make it clear that 03054A had manoeuvred again, and that it likely did occur in the one rev interim between Steve and Paul's obs last night. Here is the preliminary orbit, using Paul's and Tony's observations: Observation arc 2003 Dec 31.07 - 31.53 UTC: NOSS 3-2 (A) 0.0 0.0 0.0 4.9 v 1 28095U 03054A 03365.48661053 .00000058 00000-0 10000-3 0 06 2 28095 63.4304 229.6815 0124883 178.7250 181.4117 13.40602325 04 The new mean motion very nearly matches that of 03054C, which Tony's obs confirms still had not manoeuvred: WRMS residuals = 0.021 deg Observation arc 2003 Dec 17.78 - 31.53 UTC: NOSS 3-2 (C) 0.0 0.0 0.0 4.9 v 1 28097U 03054C 03365.48674127 .00000030 00000-0 52746-4 0 08 2 28097 63.4373 229.8536 0127165 180.3311 179.7650 13.40601466 04 WRMS residuals = 0.019 deg So my prediction that 03054C would manoeuvre to stabilize their separation was incorrect. It was 03054A that made the necessary manoeuvres. I will try to determine the time and location of the recent manoeuvres, and will report my findings. Ted Molczan ----------------------------------------------------------------- To unsubscribe from SeeSat-L, send a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@satobs.org List archived at http://www.satobs.org/seesat/seesatindex.html
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