Burnham Sunrise Ray

1997 May 13

Several San Francisco Bay area observers saw the apparition of the Burnham sunrise ray, which had been predicted for about 0230 UT on 14 May, 1997.

I myself first looked for the ray at 0230, from outside my residence in Palo Alto, California, with a 63 mm f/5.6 Brandon refractor at 142x, but did not see it. Sky conditions were not good -- the Sun was still up, there was thin, high cirrus, and the seeing was terrible. Also, the ray may not have started yet.

Later in the evening, I joined a scheduled "close-in" star party in the hills of the San Francisco Peninsula that overlook Palo Alto. At 0430 UT, the apparition was still in progress, and very pretty through several instruments: We could see the ray easily in a 6-inch f/8 Cave Astrola at 75x, in a 70 mm Tele Vue Pronto at 98x, and in an 8-inch Celestron Ultima 2000 at 267x. By that time the walls of Burnham and much of the high terrain a little to the (Selenographic) west were illuminated by direct sunlight, but the low plain immediately to the west was still in shadow, and the ray lay across it, clearly visible as a fine streak of light, looking almost luminous.

A couple of the observers present were confused about exactly where the ray was: Being familiar with the brighter and easier Hesiodus sunrise ray, they were expecting a ray that trailed from a crater wall *into* a crater. But the Burnham ray lies outside the walls of Burnham, between the crater and the terminator.

Not much happens on the Moon, but low sun-elevation rays such as these are fun to chase down and look at.

Jay Reynolds Freeman; last updated: 1997 May 14