Marco Langbroek's finding of a 5 min. period of variation of brightness of MUOS 5 in GTO reminded me AEHF 1's similar behavior in GTO. Analysis of data derived from a video by Kevin Fetter revealed a period of variation of 301.1 s. Assuming rotational symmetry of order 2, then AEHF 1's period of rotation was 10 min., for a rate of 0.1 RPM. This was consistent with the known initial rate of rotation of some other payloads built on the same bus, Lockheed Martin's A-2100. Details here: http://satobs.org/seesat/Aug-2010/0385.html Subsequent observations by Derek Breit and Brad Young confirmed AEHF 1's period of variation. Applying the same method of analysis to Marco's MUOS 5 observations yields a nearly identical result: Maximum Time (UTC) 0 2016 Jul 04 23:40:45 1 2016 Jul 04 23:45:50 2 2016 Jul 04 23:51:00 6 2016 Jul 05 00:10:55 9 2016 Jul 05 00:25:55 10 2016 Jul 05 00:30:40 11 2016 Jul 05 00:35:55 12 2016 Jul 05 00:40:30 13 2016 Jul 05 00:45:55 Slope = 299.55 s Intercept = 23:40:53 UTC rē = 0.999962 The near-unity coefficient of determination of the linear regression confirms the reliability of the slope and intercept, with the caveat that the sample is small, and the numbering of maxima 6 and 9 are based on my assumption that the period of variation was about 300 s. MUOS also is built on the A-2100 bus; therefore, its 0.1 RPM rate of rotation in GTO is not surprising, but it is good to know. Ted Molczan _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-lReceived on Thu Jul 07 2016 - 12:25:37 UTC
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