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Two More Lunar Impacts Confirmed

Forwarded From David Dunham (dunham@erols.com)
Subject: Two more lunar impacts CONFIRMED, on 2 videos

     Pedro Valdes Sada reports two lunar flashes that he
videorecorded near Monterey, Mexico, about half an hour
after the event seen by Brian Cudnik and recorded by me
that is now so famous.  He gives the times in his message,
copied below.  They are also on my tape, made in Mount
Airy, Maryland, at the times he gives!  Later today, we
will digitize these two new flashes and put them up at
http://iota.jhuapl.edu
They are also near the lunar equator.  We will be=20
determining the exact times from the tapes when we can;
I'm sure they will agree to within the 1/15th or so
second of timing that we can probably recover from the
tapes.  I had a WWV minute tone recorded at 5:07:00 UT,
7 and 8 minutes before the flashes, respectively.  The
new objects are also probably Leonids, since it was still
near the time the peak was striking the Moon, but of
course we do not know for sure, since we don't know from
which direction the meteoroids approached the Moon.

For observers, a key to my success in this endeavor was
the focal reducing lens that I purchased from Orion;
it decreased the f-ratio of my 5-inch Schmidt-Cassegrain
telescope from 10 to 6.3.  That not only increases the
field of view by more than a factor of 3 in area, but
also increased sensitivity by concentrating the seeing
disk of point sources onto fewer pixels, and allowed,
for example, recording (faintly) the Earthlit dark side
of the Moon.

By measuring images showing the lunar cusps and terminator
taken before and after the 4:46:15 UT event, I was able
to determine that it occurred at an angle (measured from
the Moon's center, called "cusp angle" in occultation
terminology) of 77 deg. from the north cusp.  Using also=20
the distance of 1.7' in from the edge, this puts the
impact point in Oceanus Procellarum (Ocean of Storms)
about 50 km east-northeast of the center of the 50-km
crater Cardanus, at selenographic longitude 71 deg. W.,
latitude 14 deg. N., with estimated accuracy of 2 deg. or
50 km.

David Dunham, IOTA, 1999 November 23
_______________________________________________________
Date: Tue, 23 Nov 1999 03:00:33 -0600
From: Pedro Vald=E9s Sada <psada@ix.netcom.com>
To: Joan and David Dunham <dunham@erols.com>
CC: David Dunham <david.dunham@jhuapl.edu>
Subject: Re: Lunar impact seen & videorecorded; more records sought

    Hi David,

    I videotaped the non-illuminated side of the Moon for a while before the
leonid meteor radiant rose. There was some trouble while doing it because
I had allready committed myself to help with a large number of people that
attended a talk I gave that night on the subject and then stayed for the
meteor shower. So I had to keep an eye on the camera and telescope at
the same time I was answering questions and talking with people.

    I checked my tape for the 4:46:15 UTC meteor crash on the Moon and
could not find it. I must have been aiming elsewhere. I am not sure where
because the FOV was too bright from the glare and I could not see the limb.
Another problem was that the portable telescope was not polar alligned
very well and I had to keep adjusting it every 5-10 minutes so the Moon
would not drift out of the FOV.

    At any rate, I have not checked all the tape, but managed to identify=
 two
very suspicious-looking flashes that lasted at most 2-3 frames. They=
 occurred
at 5:14:13 and 5:15:20 UTC (+-1 second). Please check your tape and
pass it along to see if anyone else can confirm them. The second one in
particular, was right on the edge of my camera's FOV. The first one I am
pretty sure was real since the image was a bit out of focus and
looked very much like the stars I taped for calibration after the Moon set
(the focus must have drifted since it was OK at the start of the night). I
will try and digitize the two frames involved. Unfortunately, on my VCR I
can only freeze-frame the second fainter one. There seems to be a
brighter one in between frames that I cannot freeze on the screen but can
see momentarily. As for location on the Moon of the possible impacts I
cannot say for sure since the Moon drifted constantly. I can say that it was
near the equator and close to the terminator since it drifted into the FOV
after a couple of minutes.

    Sorry that I cannot be more precise on the location and magnitudes. I
will try to grab the images involved and at least get a rough estimate of
the magnitude.

    Regards,

    Pedro Vald=E9s Sada
    Univ. de Monterrey, M=E9xico


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