Flashing period of Ajisai (object 16908) at about 2.2 seconds

From: alain.figer@club-internet.fr
Date: Thu Sep 22 2011 - 13:36:26 UTC

  • Next message: Leo Barhorst: "Re: Flashing period of Ajisai (object 16908) at about 2.2 seconds"

    Hi all,
    On sept 14th, I took 2 series of photographs of the nice flashing satellite Ajisai (EGP) 1986-61A, while it passed by Beta Ophiuci (21h04.5 UT) then by Eta Scuti (21h06.6 UT). At first glance, the flashing pattern varies significantly, because a lot of flashes are either missing or visible, however it was rather easy to discover  that a same pattern is repeating every 2.2 seconds or so. The accuracy on this photometric period (2.2 plus or minus 0.15 second) was limited by a 'rough' calculus of the angular speed of the satellite. I couldn't measure it directly on the photographs as usual (each pic being of 4 second exposure time) because only dots are visible so that I cannot define accurately the very beginning and the very end of the 4-sec track. Otherwise it would be easy to guarantee a period at 0.01 sec, due to the sharpness of the dots.
    I issued as examples, 2 such photos on my Flickr's site :
    Alain Figer, France
    2.128° E  ; 48.673°N  ; 170 m asl
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