Celestial optical transient or geosynch glint?
Roland Vanderspek (roland@blitz.mit.edu)
Thu, 18 Mar 1999 11:49:29 -0500 (EST)
Hello!
One of the reasons I joined this mailing list many moons ago was my interest
in short celestial optical flashes and how they can be confused with satellite
glints. I ran an automated observatory in Arizona for six years which was
designed expressly to detect any short flashes of light brighter than about
9th magnitude. As you might expect, my database of transients is dominated
by satellite glints or streaks.
In the time we ran this observatory, we came up with no optical transient
which we could correlate with the phenomenon we were examining, gamma-ray
bursts. In the meantime, however, a 9th magnitude transient has been
detected simultaneous with an extremely bright gamma-ray burst, so at least
now we know that optical transients from these sources exist. There are
now many automated instruments which look for these transients based on
triggers given by orbiting satellites (which occur about once per day).
(Sorry for the long-winded intro!).
What I need some help with today is the following. One of these instruments
followed up a gamma-ray burst trigger with a wide-field CCD system. In one
30-second exposure, in which time they probably get to 14th magnitude, they
saw an unknown optical source at V=12.5: in a subsequent exposure, the source
was gone. The site of the telescope is California (121.87W, 37.88N, elevation
maybe 500ft), and the transient was seen at RA=147.54, dec= *** -4.95 ***.
When I saw the -4.95 degree declination, I thought "geosynchronous satellite".
And then I thought about seesat!
I'm currently not well set up to pull satellites from OIG and check whether
one of them might have been in that location as seen from California (it's
one of many things on my "do in my spare time" list). I'm also not very
familiar with geosynchrous satellites and flashes from them: with my
instrument I saw steady geosynchronous satellites at about 8th magnitude,
but that's a long way from 12.5.
I was hoping someone on seesat could either give me a brief primer on the
subject (is a flash at V=12.5 common?) or point me in the correct direction
for reading up on the subject. In the meantime, I'll kick the OIG to the
top of my list and see what I can do there.
I'm grateful for any help, and many thanks in advance. If this is not an
appropriate use of this list, I apologize.
Roland Vanderspek
roland@space.mit.edu