L.T.P. REPORT

4 JUNE 1986

REINER

This is an observation made by David O. Darling of Sun Prairie, Wisconsin, USA. Located at Latitude 43d 11m 17s Longitude 89d 12m Elevation 990 feet.  Using a 12.5 f5 Cave Newtonian reflector with 20mm, 9mm and 10mm eyepiece.

I was out on the morning of 4 June observing the planet Mars. While studying Mars the crescent Moon  rose giving me a splendid view of the earthshine portion of the disk. As the Moon rose higher into the sky I decided to turn the telescope onto it to examine the earthshine region of the Moon. I have made it a practice to examine this region of the Moon to monitor for craters that appear to glow under this light. While observing I became aware of a black spot located  in the sunlit portion of the Moon about 60 miles west of the sunset terminator. At first I thought the black spot was a shadow being cast by a large mountain or crater. When looking at my lunar charts I could not locate any feature that would account for it. As I continued to study the black spot I realized that it appeared darker than any shadows on the Moon. It was at 4 June 1986 4:15 A.M. CDT or 9:15 U.T. when I first sighted the phenomena and it was at 4:25 A.M. CDT or 9:25 U.T. that I realized I was seeing a lunar transient phenomena event. It was at this time that I could start to see silvery filaments or streaks in the black patch. Between 9:23 and 9:25 U.T. I watched the black patch disappear. When the black spot had disappeared I found that the location of the black spot was over the crater Reiner. I estimated that during the L.T.P. event that area covered by the black cloud was approximately 40 to 50 square miles. I also had examined other formations on the Moon during this event and none were exhibiting the same phenomena witnessed over the crater Reiner.

During this observation the seeing on scale of 1 to 10 was a 6. The sky was clear and steady, the age of the Moon was 27 days. At the time of the observation the Moon was 9.02 degrees above the horizon.

I submitted a report to Sky and Telescope magazine and the observation was published in the October 1986 issue on page 425.

The following three drawing were taken from my observing log. The drawing show the decline of the black cloud over Reiner.

Drawing done at 9:15 U.T.

Drawing done at 9:20 U.T.

Drawing done at 9:33 U.T.

The rendition of the Moon shown above was done by Reading Information Technology Inc. (RITI). I have label the crater Reiner showing is location on the Moon at the time of the event.

Of all the lunar transient events that I have witness before and after this event, I must say this was one of the most spectacular displays I have ever seen.

David O. Darling with his 12.5 f5 Newtonian Reflector

December 1986