In my earlier update, for epoch 03342.7, I did not include the Centaur, because Russell Eberst's single observation had it running 0.79 s late. Russell checked his reduction, but found all in order. He had used an excellent star pair, and his position agreed closely with my epoch 3341.76 elset, so I decided to let future obs resolve the matter. Peter Wakelin's obs of consecutive passes ending at epoch 03343.79, revealed the object running later still, proving that Russell's point is indeed accurate, and indicating that the object had recently gained altitude. First, I looked for a single-impulse event, and found some indication of one on 2003 Dec 07, between about 17 h - 18 h UTC. However, it would have been very tiny, reducing the mean motion by just 0.00012 rev/d, so I evaluated the alternative: a steady acceleration over the entire arc since launch. This produced an excellent fit to most of the points since late Dec 03 UTC, with a significant negative rate of decay, so I suspect the Centaur is still venting propellant, and getting a tiny boost as a result. Observation arc 2003 Dec 07.70 - 09.80 UTC: NOSS leader 0.0 0.0 0.0 4.9 v 1 71001U 03054A 03343.77910648 .00000057 00000-0 10000-3 0 05 2 71001 63.4259 285.0442 0127151 180.9376 179.1429 13.39783980 00 WRMS residuals = 0.014 deg Observation arc 2003 Dec 07.70 - 09.80 UTC: NOSS trailer 0.0 0.0 0.0 4.9 v 1 71002U 03054B 03343.77945003 .00000057 00000-0 10000-3 0 09 2 71002 63.4329 285.0679 0124587 180.9254 179.1558 13.39757203 08 WRMS residuals = 0.017 deg Observation arc 2003 Dec 03.97 - 09.79 UTC: NOSS 3-2 r 10.1 3.0 0.0 3.7 v 1 71003U 03054C 03343.77469956 -.00002230 00000-0 -38302-2 0 09 2 71003 63.6867 284.6485 0139957 183.5168 176.4888 13.40519591 02 WRMS residuals = 0.020 deg 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
This archive was generated by hypermail 2b29 : Tue Dec 09 2003 - 20:29:26 EST