1997 Apr 10

Eight or ten observers showed up at the Montebello Open Space Area, in the hills above Palo Alto, California, at the back-up parking lot, on the evening of 10 April. The evening began cold and heavily dewy, and with poor seeing, but as the night wore on, all three conditions improved remarkably. Several folks found Mercury before it set, but the main feature of the evening was the occultation of Aldebaran. Notwithstanding the calculated small time that it takes for the Moon's disc to pass in front of the tiny star, several of us noted that disappearance and reappearance appeared to take a few tenths of a second -- notably longer than "instantaneous". Perhaps this result -- at least for disappearance -- is a consequence of persistence of vision, in which case it might be expected more and more at larger apertures, because of brighter images. I was observing with 90 mm at 162x, and saw the effect both times.

The Moon itself provided a lot of entertainment. Mare Crisium was just barely completely exposed -- I agree with Cherrington (I think) that it resembles the face of a teddy bear; another person thought it looked like a hedgehog. The great craters Langrenus, Vendelinus, Petavius, and Furnerius, were all well placed, and the Petavius rille was particularly obvious. Further north, the east wall of Endymion cast a broad shadow well into the crater. Another observer pointed out a long, narrow, unnamed valley closely adjoining Mare Crisium to the southeast and south; it starts approximately at Condorcet, appears interrupted by Auzout, then passes northwest of Firmicus and Apollonius. This feature shows poorly in Rukl's atlases, but is well photographed in chart I of Cherrington's _Exploring_the_Moon_.

Mars was a disappointment at first, but as the seeing improved, we were able to see a lot of detail. In my 90 mm Vixen fluorite refractor, at 162x, I could see the north polar cap and the dark band around it, and a hint of shadowy detail elsewhere on the disc. The longitude of the central meridian was about 190, so the face of Mars turned toward us was relatively featureless. A Meade 7-inch Maksutov showed all of this detail more clearly, at 381x -- the dark stuff north was some of the markings around Propontis II, while to the south lay Mare Cimmerium and Mare Sirenum. Best view of the night, however, was in a 6-inch Cave Astrola (Newtonian) at 240x; it clearly showed more Martian detail than the Meade Maksutov.

Comet Hale-Bopp was putting on its usual good show. Through the Vixen at 81x, I could see three 150-degree arcs of the "lawn sprinkler" structure.

I looked at a few old-favorite double stars; gamma Virginis and epsilon Bootis were easily split at 162x in the Vixen. Seeing was such that the Airy disc and diffraction rings were generally visible but not always steady. And a fine meteor of magnitude at least as bright as -3 rounded out the night.

Jay Reynolds Freeman; last updated: 1997 Apr 11