Re: No Geosats ............

From: Bjorn Gimle (
Date: Sun Mar 10 2002 - 15:29:23 EST

  • Next message: Bjorn Gimle: "Re: 88-080B tumble/flash obs; John Locker's photo"

    It is not easy to capture geosats at random (I've tried!)
    If you photograph near the the shadow entry/exit circle at the time around
    equinoxes when the Sun has the same declination as your geostationary,
    operational satellites, these satellites may be bright for several minutes,
    and are easily captured on film.
    At other times and directions, you must know the position of known bright
    And many of these just flash a few minutes per night, so you have to choose
    the right period. And the flashes are usually 1/10 second or so, and you
    have to photograph the whole period to get enough light (NB with a
    stationary camera!).
    If enough accurate flash positions (/times) are reported spread over a long
    arc of the sky (actually the midpoint of Sun and flash directions) the
    positions of future flashes can be predicted.
    ----- Original Message -----
    From: "Sebastian Stabroth" <>
    To: <>
    Sent: Sunday, March 10, 2002 6:45 PM
    Subject: Re: No Geosats ............
    > Hi John & list,
    > I also have my problems with GEO sats. ;-)
    > This image above was recorded on 2001-07-23 from 21:00 to 21:30 UTC.
    > The bright star in the upper left is Atair in Aquila. It shows at
    > least 3 satellite tracks and on the lower right corner a tumbling
    > payload or rocket body (?) but also no signs of GEO sats.
    > Well, I'm not sure, but I think what looks like GEO sats in this
    > photo are in real scratches on the film. Any ideas?
    > You can compare this photo with another one I took on the same film
    > ( It shows an
    > Iridium flare with -7mag on the same day and was taken from
    > 22:50-22:57 UTC. My location at that time was 51.905 deg N, 11.068 E.
    > Cheers,
    > Sebastian
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