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(meteorobs) Excerpt from "CCNet, 25 November 1999"
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From: Benny J Peiser <b.j.peiser@livjm.acdot uk>
To: cambridge-conference@livjm.acdot uk
Subject: CCNet, 25 November 1999
Date: Thu, 25 Nov 1999 14:50:21 -0500 (EST)
CCNet, 25 November 1999
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(1) FIVE LUNAR IMPACTS NOW CONFIRMED
Joan and David Dunham <dunham@erols.com>
[...]
=============
(1) FIVE LUNAR IMPACTS NOW CONFIRMED
From: Joan and David Dunham <dunham@erols.com>
Subject: Two more confirmed lunar impacts - now 5
David Palmer reports two more lunar impacts that he videorecorded at
his home in Greenbelt, Maryland at 3:49:41 and 4:08:00 UT of 1999
November 18. The times are estimated to be accurate to +/-3 seconds
since they were obtained just by calibrating the VCR clock with time
from the CNN cable TV broadcast. The flashes are also in the video
recording that I made at Mount Airy, about 60 km to the northwest,
bringing the total now to five confirmed lunar impacts, four of them on
my tape and also on other videotapes made by others, and the other, the
first one reported, confirmed with Brian Cudnik's timed visual
observation.
Brian Cudnik reports that the flash he saw was yellowish-orange in
color, redder than nearby psi1 Aquarii. All of the videorecordings are
black-and-white. A third probable untimed visual confirmation of that
event has been provided by Steve Hendrix, who watched the dark side of
the Moon with a 4.5-inch Meade telescope from Cameron, Missouri from
4:40 to about 4:55 UT. It was the only flash that he saw during that
period and it matched Brian Cudnik's description. Before hearing about
Cudnik's and my description of the flash, Hendrix was hesitant to share
his observation since he had "never seen anything like this before and
didn't want to appear over zealous".
A summary of the five confirmed lunar impacts are given in the table
below. This is an ASCII plain text table that must be viewed with a
fixed-space font such as Courier for the columns to line up properly.
For the time being, we are naming these with letters in the order of
discovery. The UT date is 1999 November 18. In each case, the events
were confirmed on my videotape made at George Varros' backyard in Mount
Airy, Maryland, and the timings are from my tape.
Accuracy, Approx. Discovered Selenographic
Name U.T. sec. Mag1 Mag2 by Long. Lat. Description
h m s
D 3:49:40.5 0.4 3 7 David Palmer 48W 1N 175km SW of Kepler
E 4:08:04.1 0.6 5 8 David Palmer 70W 15S 175km S of Grimaldi
A 4:46:15.2 0.1 3 8 Brian Cudnik 71W 14N 50km ENE of Cardanus
B 5:14:12.93 0.05 7 8 Pedro Sada 58W 15N 200km WNW of Marius
C 5:15:20.23 0.05 4 7 Pedro Sada 59W 21N 75km S Schiaparelli
Mag1 is the approximate magnitude of the flash estimated from my tape on
the half-frame on which it first appears. Mag2 is the estimated
magnitude a half-frame, or 1/60th second, later. In all cases except D
I can't see any evidence of the flash in the half-frame 1/30th second
after the first one, except for D, where it seems to appear there at
about 9th mag. The selenographic locations for D and E are very
approximate, based on rough estimates rather than measurements, and
could be in error by 5 deg. or more. The others should be accurate to
within about 2 deg. or 50 km. All of these are in the western part of
Oceanus Procellarum (Ocean of Storms) except E, which is in highlands
area a short distance west of the western shore of Oceanus Procellarum.
The times of B and C have been determined by Don Stockbauer, Victoria,
Texas, after creating an accurately time-inserted copy using an IOTA-
Manly video time inserter. He also determined the time of A, but for
technical reasons to less accuracy; it will be possible to refine it
later. D and E have been timed from the tape just using a stopwatch.
Several have asked me how large the impacting meteors are, and if the
new crater they form might be seen. I need help from an expert in
impact dynamics on this - I don't have expertise in that field. I have
heard one estimate that the impactors, to produce flashes this bright,
are meter-size, but another estimate is that they may be just 100 grams
or so. In any case, I believe that the "splash" that these objects made
are less than 100m across and will not be visible with Earth-based
telescopes. In 2003, the Japanese Selene spacecraft plans to map the
Moon from low orbit in detail, and coparison of its images with those
of Lunar Orbiter, Apollo, and/or Clementine will hopefully reveal some
small new craters.
Ray Sterner and I digitized our images of B and C yesterday and we
hoped to get them posted on our Web site at http://iota.jhuapldot edu, but
that might not be possible now until Monday. In the meantime, we will
post the latest information about these flashes at the main IOTA site at
http://www.lunar-occultations.com/iota
including Sada's images of B and C, and Palmer's images of D and E. I
don't plan to make any more mass-mailings like this one about these
events, but will distribute future updates to a few who are especially
interested. Otherwise, check the Web site for further updates, but I will
try to answer specific questions about these events.
David Dunham, IOTA, 1999 November 24
PS - After sending this, I will not be at this address, but will be
reachable at david.dunham@jhuapldot edu, phone 1-240-228-5609.
Joan and David Dunham
7006 Megan Lane
Greenbelt, MD 20770
(301) 474-4722
dunham@erols.com
[...]
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