Image intensifier search system

Allen Thomson (
Mon, 13 Jan 1997 15:29:16 -0800

   This message from sci.astro.amateur seemed to be of possible 
intrest to Seesat-L subscribers, so I obtained the author's 
permission to repost it here.

   I assume but don't know that the meteors were identified 
through frame-by-frame inspection of the video.  Depending on 
system details, a somewhat different approach might be needed if 
one were looking for satellites.
From: Tom Polakis <>
Newsgroups: sci.astro.amateur
Subject: Meteor Count Down to 9th mag
Date: Thu, 09 Jan 1997 18:30:25 -0500
At the last meeting of the East Valley Astronomy Club, Pierre Schwaar
showed a videotape of highlights of the Geminid meteor shower.  His
latest effort involved attaching an aerial lens to a cheap image
intensifier.  The resulting field of view is about 10 degrees, and the
system reaches about 9th magnitude.
Pierre scanned the sky slowly on the night of the peak of the Geminid
meteor shower.  He recorded between midnight and dawn in one-minute
samples throughout the period, and counted the number of meteors in 45
total minutes of recording.  The results were impressive.
In those 45 minutes, the system recorded 19 Geminid meteors.  His
scanning technique and all-morning coverage minimized the chances of any
bias toward the radiant, so he was able to make a good estimate of a
zenithal hourly rate.  Let's say that the typical meteor-watcher covers
about 120 x 80 degrees, or about 10,000 square degrees.  His lens covers
about 80 square degrees, or about 1/100 of the naked eye field.  Now,
his 19 meteors in 45 minutes scales up to a rate of over 2000 meteors
per hour!  Again, he is recording meteors down to about 9th magnitude.
I wonder if similar studies have been done with image intensifiers.
Everybody knows that star count increases greatly with each magnitude
step, but what is this rate for meteors?
                Tom Polakis
                 Tempe, AZ