Re: Help to identify (re)entering object

From: Alan Pickup (alan@wingar.demon.co.uk)
Date: Fri Nov 07 2008 - 23:49:57 UTC

  • Next message: Peter Wakelin: "SATOBS 2008 November 07"

    As seen from that location at 07:00 UTC on October 24, the Sun would
    have been about 1 degree above the horizon in the ESE (azimuth 106
    degrees).
    
    If I was asked to guess, I'd say that the photo was taken looking E to
    SE under bright twilight conditions a few minutes before 07:00. The
    circumstances (Sun just below the horizon in the general direction of
    the observation) would have been ideal for the observation of a sunlit
    aircraft condensation trail as it shone brightly by forward scattering
    against a sky that is slightly darker than full daylight.
    
    I have seen several images showing such contrails that look very similar
    to this one. Some of these were reported as possible meteoric fireballs
    or satellite reentries, but the duration of visibility (sometimes
    minutes) was inconsistent with the likely duration of such phenomena. A
    meteoric fireball is unlikely to last for more than 5-10 seconds, while
    a reentry could take a minute or two to cross the entire sky, but would
    take only seconds to cover the apparent arc shown on the photograph.
    
    Incidentally, Soyuz TMA-12 landed at 03:37 UTC on October 24, so could
    not have been the cause. SpaceTrack reports no other satellite decays on
    that day. If this were a Taurid fireball (which I doubt) then the
    apparent downwards direction of motion in the E to SE would be
    consistent with the position (low in the W) of the two radiants of the
    Taurids complex.
    
    Alan
    -- 
    Alan Pickup /
    Edinburgh  /
    Scotland  / COSPAR 2707:  55.8968N   3.1989W   +208m   (WGS84 datum)
    
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