COBRA HEAD

L.T.P. EVENT

16 MARCH 1992

00:39 TO 00:55 UT

BY

DAVID O. DARLING

OR

RECURRENT LUNAR PHENOMENA (RLP)

On 16 March 1992 at 00:55 UT, two members of the Madison Astronomical Society (MAS) of Madison, Wisconsin observed a lunar transient phenomena. The two observers Dave Weier and myself observed a luminous glow in the vicinity of the Cobra Head. We were using a Celestron SCT 11"  f10 that belong to the club.

We began our observing session at 00:39 UT, to conduct a routine search for lunar transient phenomena (L.T.P.) It was shortly after we began to examine the crater Aristarchus and region that Dave Weier mention he could see the Cobra Head and Schroter's Valley with in the shadow being cast upon it. He said that it appeared to him as a faint illumination with in the shadow area. When I examined the feature I noticed that the shadow being projected over the Cobra Head was soft and diffused and had a strange appearance along its edge. We both came to the conclusion that an L.T.P. was taking place. It was at 00:52 UT that I mounted my Minolta SRT 101 at eyepiece projection and began taking photographs until the film was used up. 

When I examined the photographs once they were processed, I found two pictures that showed changes taking place with in the shadow region just North of the Cobra Head formation. 

Photograph © 2004 by David O. Darling, Director L.T.P. Research

Photograph taken March 15, 1992 at 00:53 UT, exposure 4 seconds, using Celestron SCT C11 f10 at eyepiece projection using 10mm/279X. Kodachrome Slide Film ASA 64. 

The photograph shown above shows the region just north of the Cobra Head to be in dark shadow. It would then go soft and appear to have a faint illumination inside the shadow area. The shadow has a sharp edge to it at this time.

Photograph © 2004 by David O. Darling, Director L.T.P. Research

Photograph taken March 15, 1992 at 00:55 UT, exposure 4 seconds, using Celestron SCT C11 f10 at eyepiece projection using 10mm/279X. Kodachrome Slide Film ASA 64.

The photograph shown above here show that the sharpness of the shadow edge has disappeared. This nebulous appearance would come and go several times during the observing session which run from 00:39 to 00:51 UT. At 00:52 UT I mounted the Minolta SRT 101 for eyepiece projection.

Rendition of Moon made using the Reading Information Technology Inc. RITI Lunar Map Pro. The red spot indicates the location of the nebulous shadow.

Drawing by Dr. Anthony Cook done on 8 September 1987 at 20:55 UT.

"The Herodotus region was observed at 20:55 U.T. the interior shadow on the East rim of Herodotus was black and distinct. The North of Herodotus, at the head of Schroter's  Valley was a dark gray region which was not distinct. When observed through a Polaroid filter, no apparent change in appearance was seen when rotating filter."  Dr. Anthony Cook.  This observation is another example where seeing and fine detail blurs stuff out making it look hazy.

Apollo Program Photograph 

The photograph depicted above was taken during one of the Apollo programs to the Moon. The mission # is not known. This photograph shows the Cobra Head and the very beginning of the Schroter's Valley. 

CONCLUSION: When I examined other evidence along with what is presented here.  I found  I was not witnessing a true lunar transient phenomena event, but the natural occurring appearance of this unique geological feature or recurrent lunar phenomena (RLP). When the sun rises on this feature what takes place is the high ground to the East of Schroter's Valley cast a shadow that crosses over the width of the valley. At a certain point during the sun rise the western side of the valley start to become illuminated. This illumination is only a narrow line of light. The lip of Schroter's Valley which is higher than the ground to its west, which slopes away remains in shadow. This gives the illusion that the two shadows are one and this becomes a nebulous patch when the narrow line of illumination goes in and out with the seeing. If you were to watch this sunrise long enough you would see the illuminated line of the west wall of the valley get wider and seeing would have less effect upon it. Another factor that plays heavily into the observers perception of what going on is the aperture of the telescope. As you know the larger the aperture the better the contrast and resolution. The smaller telescopes would have trouble resolving this small linear feature and thus show it as a nebulous patch. I also had contact to other observers Neil Simmons of the Milwaukee Astronomical Society and Craig Wandke of Monterey, California who both observed this same kind of phenomena on two seperate dates.

Photograph of Dave Weier who witness this event, looking through the same telescope used on the night of the event. 

This observation can be tested by viewing the Moon during the similar lighting conditions using the Lunar Observer's Tool Kit developed by Harry Jamieson.