Photographing geosynch satellites

Ron Lee (scubalee@pcisys.net)
Tue, 23 Jul 1996 20:22:50 -0600 (MDT)

Two years ago I photographed the first two Direct TV satellites.

I piggy back mounted a 35 mm camera and 100-300 mm telephoto lens
onto the top of a Celestron 8 telescope.  When the satellites came
into view in the telescope, i disconnected the telescope clock drive
so that the camera was pointed at the satellites.

I used varying exposures and focal lengths with Ektachrome 200 slide
film at f/5.  Some did not reveal any satellites at exposures of 20
minutes, which is not surprising since visually the same variation
in brightness was also observed over a course of several hours and
on different dates.

A similar camera system could also be mounted on a tripod and aimed
at a star known to be near the geosynch satellite desired.  The 
camera would be set to "BULB" or "B" and a cable release used to start
the exposure.  Lock the cable release open until the exposure is
complete.

Approximate field of view (FOV)on 35 mm film is as follows"

      Focal length (mm)       FOV (degrees)
           100                13.6  x  20.8
           200                 6.8  x  10.4
           400                 3.4  x   5.2

Exposures need not be as long as 20 minutes. I would suggest
varying exposures of a few minutes , 5, 10 and maybe 20 minutes.

Ron Lee