Re: Satellite Track or Meteor?

[<aah@nofs.navy.mil>]

Chris mentioned that radar is the best instrument
for tracking space junk.  That is only true for low
earth orbit or extremely large pieces.  The received
reflection goes as r**4 and you soon lose the ability
to detect small pieces.  We do a fair amount of tracking
of space debris near geosync using optical imagery.
  You can't say the object is brighter at V or I until
you calibrate the field and extract the data.  Brightness
is often deceiving, especially if the focus is different
between the two cameras.  This was an observation near
twilight and so is most likely a piece of space junk
due to solar reflection.  You rarely get uniform rotation
from meteors.  You also don't know the rotation period
other than in pixels since the object doesn't necessarily
take 100 seconds to cross the field of view; that was just
the length of time the shutter was open.  True meteor cameras
get the movement speed by adding a rotating shutter to the
system that interrupts the trail at specified times.
  Regarding government cameras and variable star measurements,
just remember that the GEODSS system is the basis for LINEAR,
the major asteroid discovery program underway in New Mexico.
Most DoD cameras are designed for tracking rockets and so
do not have the right parameters or detectors for most
variable star work, just as the Mark IV has its limits.
Arne