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(meteorobs) [IMO-News] Two more confirmed lunar impacts - now 5 (fwd)




------- Forwarded Message

Date: Wed, 24 Nov 1999 22:41:47 +0100 (MET)
From: Sirko Molau <molau@informatik.rwth-aachendot de>
To: imo-news@egroups.com
Subject: [IMO-News] Two more confirmed lunar impacts - now 5 (fwd)

- ---------- Forwarded message ----------
Date: Wed, 24 Nov 1999 12:49:08 -0500
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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