Lade Lunar Sunset Ray

Observer: Tony Donnangelo 
Date/time of observation: 2003/08/19 06:07 U.T.
Site location: Tuscarora State Forest, PA, USA 
Site coordinates: N. 40.51° W. 77.63°
Site elevation:  427 meters (1402 feet)
Site classification: State forest wilderness area 
Instrument: 14.5” Starmaster Dob.
Magnifications: 203x, 267x, 373x
Object: Lade (crater)

I was setup before sunset. Unfortunately, it was completely cloudy until 03:00 U.T. (11:00 p.m. local time), when clearing commenced and the moon became visible within the tree line. Light dew started forming at nightfall and became very heavy by 06:30 U.T. I began observing the moon as it cleared the trees at 03:50 U.T. Seeing was very turbulent, but transparency was good.

At 08:25 U.T., I just observed the end of a ray south of Tempel (see my report). I began looking for a ray predicted to occur in Lade at 09:31 (see my report). The shadows of five peaks extended approximately half the floor’s length from the western end. There are two obvious narrow breaks in the western wall. These may be responsible for some of the light beams.

By 09:15 U.T., the shadows in the northern half stretched almost to the eastern wall. A shadow in the southern half was three-quarters toward the southeastern wall. The southern pie-shaped swath of light was wide. The northeastern side of the crater wall was abutting the terminator. The remaining outer area was illuminated.

Within fifteen minutes, the northern half of the floor was completely shadowed except at the eastern interior base of the wall. The southern beam of light narrowed slightly. It ran from approximately the middle of the crater to the southeast, where a craterlet is superimposed on the wall.

Clouds moved in, and I was forced to end my observations. I’m wondering if the ray may have narrowed further. It’ll have to wait for another night.