On 24-5-2017 Alain Figer wrote, in response to my observational report: > Hi Marco, > > You wrote : > >> Obtained a long datastring (a few thousand points spanning several minutes) >> on the USA 144 decoy in order to analyse its brightness behaviour. > > I measured its photometric period on 23 May 2017 at 42.9s. I have now completed the analysis. The resulting curve can be seen in this blog post: https://sattrackcam.blogspot.nl/2017/05/updating-changing-tumble-period-of-usa.html Fitting a sinusoid to 2838 photometric point measurements obtained over a 7m 55.5s timespan, spanning pre- and post culmination, I get a peak-to-peak period of 43.528 +- 0.005 seconds (21 May 2017, 22:17:51 to 22:25:46 UT). This is close to but slightly different from Alain's 42.9 s figure above, perhaps the result of foreshortening effects. The brightness varied between mag +7.2 (R band) and invisible (= fainter than mag +9.4). The photometry was done with TANGRA on a video obatined with a WATEC 902H and Samyang 1.4/85 mm lens. - Marco ----- Dr Marco Langbroek - SatTrackCam Leiden, the Netherlands. e-mail: sattrackcam_at_langbroek.org Cospar 4353 (Leiden): 52.15412 N, 4.49081 E (WGS84), +0 m ASL Cospar 4355 (Cronesteyn): 52.13878 N, 4.49937 E (WGS84), -2 m ASL Station (b)log: http://sattrackcam.blogspot.com Twitter: _at_Marco_Langbroek ----- _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-lReceived on Thu May 25 2017 - 09:30:03 UTC
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