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Lunar Impact Observed; More Records Sought

Forwarded from David Dunham (dunham@erols.com)
Subject: Lunar impact seen & videorecorded; more records sought

     Brian Cudnik, Houston, Texas, saw a brief flash near the 
center of the Moon's dark side near the edge at about 4h 46m 20s U.T. 
November 18. Observing with a 36cm telescope, he estimated that 
the flash, taking a fraction of a second, was at least as bright as 
nearby 4th-mag. psi1 Aqr. He is sure of the event, but asked me for
confirmation, to see if a satellite glint or other close-to-Earth
phenomenon might have been involved. The observation was confirmed 
in a video recording that I made using a 13cm telescope at George 
Varros' home in Mount Airy, Maryland, with relatively dark skies 
about 35 miles northwest of Washington, DC. The event occurred at
a cusp angle of around 75 - 80N (10 to 15 deg. north of the lunar
equator) 1.7' from the Moon's edge. The flash, timed from the 
videotape at 4h 46m 15s, is visible in only two video frames, the 
first at about 3rd magnitude and the second at about 8th magnitude. 
The images can be viewed at http://iota.jhuapl.edu. The object was 
probably a Leonid since the peak of this year's display was at 2h 
UT as seen from the Earth. The trailing Moon would arrive at the 
same solar longitude about 3h later, near the time of the observed 
impact. I also recorded 5 lunar occultations of 8th-magnitude stars 
an hour before the impact, and also have an image of psi1 Aqr on
the tape. Analysis of those images and of the impact images will 
permit a reasonably good determination of the brightness and 
location of the impact flash. Anyone else who was recording the 
dark side of the Moon at the above time should check their data and 
report their results to me, preferably at both dunham@erols.com and
david.dunham@jhuapl.edu.  I am interested in knowing about ALL
observations of the lunar dark side made between 4:00 and 6:00 UT
November 18th when the Moon should have been struck by the brunt of
the Leonid storm.  There are other fainter flashes in my video
record, but some of them are spurious video artifacts. I looked at
one, and it did not have the strong stellar appearance of the
4:46:15 flash.  But before checking very much for other events,
I want to know if there are any other observations that might
confirm them.  Unfortunately, I'm affraid that most observers in
the central and western USA, where the Moon was best placed at the
time, bypassed the evening lunar observations in favor of seeing 
the Leonid meteors during the early morning hours; I have heard of
only a few lunar attempts.  At my location, fortunately conditions
were excellant with the Moon 15 deg. above the horizon at 4:46 UT.
I was able to continue the observations until 5:30 UT.

     I believe this is the first confirmed lunar impact observation. 
A probable lunar meteor impact was photographed on 1953 November 15 
by Dr. Leon Stuart; see 
http://www.spirit.net.au/~minnah/LunarFlare.html.
 
David Dunham, IOTA, 1999 Nov 21

Joan and David Dunham
7006 Megan Lane
Greenbelt, MD 20770
(301) 474-4722
dunham@erols.com

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