On May 13, 1997, a small group of TAC observers met at Montebello Open Space Preserve (above Palo Alto, CA) for lunar observing. In particular, we hoped to observe the "Burnham Ray", a ray of light from a gap in the wall of the crater Burnham. This ray had been previously observed by Jay Freeman and one or two other observers, and reported in sci.astro.amateur, but the weather had been uncooperative for the several months since that report, and the ray had not been seen again.
The predicted time for the terminator to hit the wall of Burnham was 7:33pm PDT, before sunset. I arrived at Montebello somewhat later than that, and was not set up and ready to observe until 8pm. Using Rukl's lunar atlas, I located the approprimate area where Burnham should be -- Burnham itself being a very small crater, and difficult for this novice lunar observer to identify -- and started scanning the terminator in that area, looking for rays.
Almost immediately, at 8:10, I found one, a very pretty ray coming off the side of a crater and down its wall. A quick cross-check of Rukl showed that this was definitely *not* Burnham. I tentatively identified the crater as Halley.
I watched the Halley ray for the next five minutes as I scanned the area for Burnham. The Halley ray, though pretty, turned out to be a very short-lived effect; it was gone by 8:15, five minutes after I first saw it (though of course I have no idea how long it had been going on prior to that).
Soon I found another ray, and this one was in the area where Burnham was supposed to be. A triangle of light extended from the outside edge of a crater into the interior of a larger crater. I called the other two observers over, and we all compared views, excited to have found the Burnham ray. We watched it for a few minutes, comparing views among the three telescopes present (my 6" f/8 Cave, a Celestron Ultima 2000, and a Pronto) as the last remnants of twilight faded from the sky.
A coyote chorus began, and suddenly a coyote howled *very* close to where we were set up, just on the other side of the parking lot. One observer got out a spotlight and aimed it at the sound -- and there on the hillside a few hundred yards away, two coyotes stood watching us.
About this time Jay arrived, so we asked him to confirm our observations of the Burnham ray. The ensuing conversation gradually revealed that each of us was looking at a different phenomenon. One observer had a reticle eyepiece, so we used the crosshairs to point out what each of us had been calling the Burnham ray and clear up the confusion. By this point (about 9pm), the best viewing for the Burnham ray had passed, so the ray was visible only as a break in a shadow extending off the side of Burnham. The walls of Burnham are crowned with sharp peaks, so the shadow looked like the shadow of a pine-tree- lined ridge; several observers independantly noted this resemblance.
My "Burnham Ray" was probably actually from the crater Vogul. The Vogul Ray is a pretty and very persistent phenomenon; I first saw it at 8:15, as a slim ray of light, and it was still easily visible at 9:45, as a fatter triangle against a still-black crater.
The fact that I "discovered" two new lunar rays while looking for a third suggests that this ray phenomenon is rather common, and that the lack of ray reports is mainly due to the scarcity of good books on lunar observing versus deep-sky observing. Perhaps, if there are enough interested lunar observers on the net, we can remedy this, and someone will eventually gather it into a book.
After clearing up the confusion over which ray was which, we talked about the coyote encounter. Several of us tried howling to encourage the coyotes to sing along. Unfortunately, no one joined us in our attempt at coyote karaoke (*).
We spent the next few hours observing the moon and Mars (though not much detail was visible on Mars -- the seeing was inconsistent, with thin clouds coming and going), determining which deep-sky objects could be found in small telescopes with the moon up, and trading views. I spent most of the time exploring Mare Serenitatis, looking for interesting features then using Rukl to identify them. Eventually we all got tired and called it a night.
Thursday, May 15, was another predicted ray, this time, the well-known Hesiodus Ray. I had seen this ray once before, in early twilight. The predicted time was about 7pm PDT, well before sunset. Two other observers and I gathered at 8:30, somewhat later than we had planned, and quickly found the ray, but Hesiodus was already half-lit, so the ray wasn't as impressive as it must be when Hesiodus is entirely dark. Still, the ray was fairly obvious, and remained so for the next several hours as the shadow of Pitatus into Hesiodus shortened. Trading looks through three 'scopes, we explored Mare Nubium, Mare Imbrium (with the "sheep" :-), and the areas around Plato and Tycho. In Mare Nubium, very near Hesiodus, one observer found a crater that looked like a smiley face (which turned out to be Wurzelbauer) as well as a Mickey Mouse head, a Star Trek insignia, and several other interesting features. The seeing was outstanding for a short time, enough so for two of us to become frustrated with the images we were seeing and resolve to collimate better. I tried to split the double-double (epsilon Lyrae) in my 90mm f/5.6 Maksutov, and succeeded, just barely, but the images were poor -- it needs collimation badly. After a flurry of star-testing, we returned to lunar and Martian observing, but the seeing eventually deteriorated, and we said good night to the sheep and departed.