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From: Rob Matson <mojave_meteorites_at_meteoritecentral.com>
Date: Tue, 17 Feb 2009 11:16:19 -0800
Message-ID: <GOEDJOCBMMEHLEFDHGMMCECKDLAA.mojave_meteorites_at_cox.net>

Hi Dr. Tanuki,

Thought I'd chime in on the asteroid detection comments you
forwarded to the List (from Pat Branch?) You probably know much of
this already, but obviously Pat does not. With the current network
of professional and amateur telescopes, finding 1-2 meter asteroids
at lunar distances is largely a case of luck. Remember that any
given time around a third of the celestial sphere is unavailable
for imaging of anything but the largest (brightest) objects due
to solar exclusion angle and poor phase angle, so professional
survey instruments don't waste their valuable time searching
there. So missing an incoming asteroid of almost any size (much
less a small one) coming from a direction with a solar elongation
less than 70 degrees (as was the case with Sunday's Texas bolide)
is pretty much a certainty.

The only time under-5-meter NEOs are found is when they are close
to opposition, and even then it's a matter of timing luck since
the object is only going to be near enough to be detected for a
day or two.

Best wishes,
Rob
Received on Tue 17 Feb 2009 02:16:19 PM PST