Phobos Grunt - Observation

Date: Wed Dec 07 2011 - 06:41:41 UTC

  • Next message: Greg Roberts: "Optical 06 Dec 2011"

    Yesterday evening (06 Dec) at 17.00 UTC I observed another pass. Unfortunately 
    conditions were not ideal. 
    Thin clouds were quickly moving through the expected trajectory. I managed to 
    follow PhG for about 2 minutes 
    through binoculars until shadow. Apparently, Its brightness changed slowly 
    (seconds) and irregularly at least 4 times 
    of 1 or 2 magnitudes but I can not exclude that this was due to the non 
    uniform sky. 
    However, at 17.01.38 (+- 2 s) UTC, it gave a clear short "flare" that lasted 
    about 1 second during which the brightness 
    increased of about 2 magnitudes. By using the available TLE (11340.44) and a 
    common reference frame 
    (vertical – along the velocity vector - normal to the orbital plane), I 
    computed that, if it was the flare centre, the reflective surface 
    should have been oriented with tilt of 63.8 +- 0.5 deg and angle of 245 +- 10 
    deg. (My coordinates were lat. 45.483 deg, lon. 8.558 deg).
    Best Regards,
    Seesat-l mailing list

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