Automatic satellite detection (cheap)

Allen Thomson (
Wed, 12 Feb 1997 11:44:16 -0800

   The Center for Astronomical Adaptive Optics at the University
of Arizona (my alma mater, as it happens) has installed a laser
guide star facility at the refurbished MMT on Mt. Hopkins south
of Tucson.  The US Federal Aviation Administration is understandably 
concerned that intense yellow light not be accidentally directed into
the widows of passing aircraft and requires that the CAAO post airplane 
spotters around the telescope when the guide star is in use.  This is 
a pain for the spotters and not very effective, as peoples' attention tends
to wander after a while.  The USAF Starfire range in New Mexico has similar

   Being no fools, the MMT people decided that it would be a good
idea to automate the aircraft spotting task, and developed a
device called, aptly enough, the "Automated Optical Aircraft Spotter."
It consists of an Electrim CCD camera, a wide field of view camera lens,
and a PC running some homebuilt algorithms that locate moving objects,
determine their motion, and extrapolate their future position relative
to the laser pointing direction. Equipment cost is ~US$3,000

   To nobody's surprise, the system also detects bright satellites. 

   It doesn't appear as if they do anything with the satellite data, but
it isn't hard to imagine using it to derive at least rough orbital
elements, point other cameras, send alerting messages via e-mail to
other sites, etc.