1. Orbits from observations Lacrosse 5 0.0 0.0 0.0 3.4 v 1 71001U 05016A 05121.30567409 .00001317 00000-0 10000-3 0 03 2 71001 57.0006 128.1443 0165730 17.3893 343.2720 14.91442536 05 Arc 2005 Apr 30.04 - May 01.33, WRMS residuals = 0.040 deg Lacrosse 5 r 9.8 3.0 0.0 4.8 v 1 71004U 05016B 05121.30509779 .00001315 00000-0 10000-3 0 00 2 71004 56.9969 128.1380 0159329 16.8137 343.8090 14.92106992 06 Arc 2005 Apr 30.04 - May 01.12, WRMS residuals = 0.029 deg 2. Estimated Orbit of 05016A after Circularization The following search orbits are based on the assumption that the payload will circularize its orbit about 48 h after launch, on an apogee pass within range of Diego Garcia, as was the case with Lacrosses 2, 3 and 4. In the case of 05016A, that would be tonight, 2005 May 02 near 01:55:35 UTC. I note that 05016A's initial apogee appears to be greater than that of any of its predecessors: km 88106B 687 91017A 678 97064A 676 00047A 689 05016A 709 Assuming 05016A's higher apogee is intentional, and a nearly circular final orbit, then the following search orbit applies: 703 X 709 km 1 70000U 05122.08026620 .00000044 00000-0 10000-4 0 07 2 70000 57.0006 125.0644 0004000 18.7493 182.1000 14.56000000 03 In the event 05016A manoeuvres to replicate 97064A's initial circularized orbit, the following applies: 670 X 676 km 1 70000U 05122.08026621 .00000044 00000-0 10000-4 0 08 2 70000 57.0006 125.0644 0004000 18.7493 182.1000 14.66200000 06 I recommend the following observational plan. 1. Prior to 2005 May 02 at 01:55:35 UTC, assume 05016A will not have manoeuvred, so use the 14.9144 rev/d elset derived from observations. 2. After 2005 May 02 at 01:55:35 UTC, assume 05016A may or may not have manoeuvred, so look for it first in the 14.9144 rev/d orbit derived from observations. If it fails to appear, then expect its earliest pass in the 14.662 rev/d search orbit, and its latest pass in the 14.56 rev/d orbit. It is recommended to plot all three predicted tracks. Ted Molczan ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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