New observations have been provided by Daniel Deak, Bram Dorreman, Russell Eberst, Rainer Kracht, Walter Nissen, and myself. Here are updated elements: USA 129 15.0 3.0 0.0 5.1 v 1 24680U 96072A 01130.10151620 .00018103 00000-0 25625-3 0 04 2 24680 97.8172 192.9047 0483405 355.5269 4.1740 14.81198472 08 WRMS residuals are about 0.03 degrees. The inclination now appears to have been unaffected by the manoeuvre; perigee height still appears to have increased; however, some of the points have higher than usual residuals, so further observations may change the picture. The pre and post-maneouvre orbits now appear to strongly coincide with the perigee-crossing of 2001 May 08 at about 16:23 UTC, indicating that that was the time of the manoeuvre. This is about 12 h later than my initial estimate, which was based on a few early post-manoeuvre observations. 96072A's maneouvre may have been sufficient to delay the need for the major re-boost until at least the next equator crossing of 96072A's perigee, on 2001 July 02. At typical rates of decay, the mean motion of either KeyHole is unlikely to exceed that maximum observed pre-maneouvre value of about 14.85 rev/d, before that date. The sun is unpredictable, so the satellites' operators could decide to manoeuvre on or about 2001 May 18, when USA 116's perigee next crosses the equator. My guess is that the decision would also depend on whether or not USA 116's required orbital changes require that its maneouvre take place at perigee. There are so many imponderables involved, that all we can do is to be aware of past behaviour, to help us to anticipate when manoeuvres are most likely to occur. Finally, here are my observations: 96 072A 2701 F 010510 023650.980 0.1 1038.305 2601.455 2.0 S 96 072A 2701 F 010510 023809.700 0.1 0542.577 6333.026 1.0 S 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 : Thu May 10 2001 - 07:37:01 PDT