Dunham, David
From:Joan and David Dunham [dunham@erols.com]
Sent:Monday, May 08, 2000 10:53 AM
To:David_Dunham@jhuapl.edu
Subject:Possible eta Aquarid flash timed in Calif.
Date: Mon, 8 May 2000 02:16:33 -0700
To: Joan and David Dunham 
From: "Frank A. L. Anet" 
Subject: Preliminary report of possible lunar meteor impact
Cc: Brian Cudnik 

We observed a part of the dark side of the moon, close to the 
terminator, on Saturday evening, May 6, 2000, from our new home in 
Valencia, CA, between 9:12 pm PDT and 10:00 pm PDT (May 7, UTC). We 
also saw three total occultations and timed at least one of them 
(magnitude 7.8, KO, but at an altitude of only 12 degrees and with a 
light-polluted sky).

Telescope: 8-inch (20 cm) Vixen Cassegrain with a focal reducer to 
give f/6.4 and a Watec 902H 1/2 inch high-sensitivity video camera 
(with infra-red sensitivity). The video output was displayed on a 12 
inch high-resolution BW monitor so as to show the background noise. 
Features on the dark side of the moon were clearly visible (Tycho, 
Copernicus, Kepler, Plato, etc., but most marias only could just 
barely be seen, except at the end of the period when the Moon was 
lower than 12 degrees altitude. Craters on the bright side and stars 
were dancing about quite a bit because of the low altitude and air 
turbulence. The video was also recorded in a Sony digital video 
camcorder via a Sony DVMC unit as an A/D converter. There were some 
thin high clouds at sunset, but they seemed to disappear later on.

We saw only one flash on the monitor with any confidence and it was 
also seen on the recorded digital tape (there may be others as we 
have only done a visual search so far).  The relevant part was loaded 
into a Macintosh computer via a firewire input and the file clearly 
showed the flash when examined by NIH Image. The flash occurred in a 
single field of a single frame and consisted of four or five bright 
pixels (two very bright) on one line and two less bright pixels with 
a dark line in-between (i.e., all the bright pixels are in one field 
only). The brightest pixel was about 4 times the intensity of the 
brightest pixel of SAO 77624, whose occultation we timed a few 
minutes before. We estimate the magnitude of the flash as about 6 
(the altitude was only 10 degrees).

We timed the flash with a recorded WWV signal as: 4 hr 52 min 41.63 
sec UTC (May 7, 2000).

The position of the flash on the moon is not known with great 
precision as yet, but the selenographic latitude was about 25 degrees 
north and the longitude about 5 degrees towards Mare Crisium (this is 
East according to the Canadian Observer's Handbook but it is West 
according to the map mentioned on the A. L. P. O. web site. The 
nearest visible crater was Manilius and the flash site appears to be 
close to where the 1971 Appolo landing took place

Our observing location in Valencia is at the back of our house, which 
has a good view of both the east and west horizon and has a Longitude 
of -118 deg 33.811', a Latitude of 34 deg 24.436' and an elevation of 
1290 feet, according to our Garmin III GPS (how nice it is to be able 
to get decent measurements now that SA is gone!!) ( we are making 
more measurements, but these should be very good). The occultation of 
SAO 77624 was within 1.5 sec of the time given by the (Windows) 
Occult program, and the above data are also in agreement with those 
from a USGS map of Valencia.

We do not think that the above observation is an artifact. We have 
never seen such a flash before during occultation timings or 
previously when deliberately looking for a lunar flash. Of course, it 
needs confirmation by another observer.

To-night was mostly cloudy and we did not try to observe, but 
tomorrow and Tuesday night should be clear and we plan further 
observations of possible flashes.

Frank and Ragini Anet
Anet@chem.ucla.edu
26378 Woodlark Lane
Valencia, CA 91355
Phone: (661) 799-9355