Derek Breit has reported observations of AEHF 1, running about 245 s late relative my epoch 10242.84673563 elements: http://satobs.org/seesat/Sep-2010/0004.html The late arrival is likely due to a second burn of the REA (reaction engine assembly) thrusters, probably near the apogee passage of Aug 31, at 13:25:32 UTC. Here are preliminary elements: AEHF 1 594 X 49978 km 1 36868U 10039A 10244.13816125 .00000000 00000-0 00000-0 0 05 2 36868 21.6235 306.2265 7798000 187.7859 141.3094 1.54112411 04 Arc 20100831.56-0901.17 WRMS resid 0.008 totl 0.005 xtrk I obtained the above by propagating the pre-manoeuvre elements forward, and adjusting them to fit the new observations plus a synthetic observation at the assumed time of the manoeuvre (spacecraft's position relative the centre of the Earth). Since the arc is short, I allowed only RAAN, mean anomaly and mean motion to vary; eccentricity was set manually to maintain apogee. Several iterations of this process were required to converge on a solution. I also experimented with allowing inclination to vary, but the change was little more than 0.1 deg - much less than the ~0.4 deg of the REA burn #1, and may not be real, so for now, I assume it did not change. Two to three additional manoeuvres can be expected in the coming days, resulting in a perigee of 950 km. Ted Molczan _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l
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