[Prev][Next][Index][Thread]
(meteorobs) Two more confirmed lunar impacts - now 5
In a message dated 11/24/99 1:00:18 PM Eastern Standard Time,
dunham@erols.com writes:
> 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
To UNSUBSCRIBE from the 'meteorobs' email list, use the Web form at:
http://www.tiacdot net/users/lewkaren/meteorobs/subscribe.html