Gassendi and Rima Brayley

by Jay Reynolds Freeman


On the evening of Wednesday, 27 January, 1999, I hauled my 98 mm f/6.7 Brandon refractor -- originally a 94 mm f/7 -- into my yard in Palo Alto, California, for a little bright-sky astronomy. The Moon was high, so I looked at it first. As the telescope settled, I found the seeing to be pretty good; observing with 164x -- a Meade 4 mm Research-Grade Orthoscopic -- was no problem.

The waxing-Moon terminator was near 44 degrees (selenographic) west, which gave excellent conditions for viewing the interior of Gassendi. In moments of steady seeing, I could see quite a lot of detail. I noted the pair of rilles that trend NW/SE just SW of the central peak, and also the pair that run N/S just E of the peak. The slumped area just south of Gassendi A, where the smaller crater has pushed into the rim of the larger, was particularly prominent.

Further to the north, I spent quite a while looking for Rima Brayley, but was not quite sure I could see it. I may have spotted a short portion at about 36.5 W, 22.5 N, but it was difficult to say for certain.

Tired of the Moon, I tried some double stars. I could see A through F in the Trapezium, but F was very difficult due to the bright sky. E and F are commonly easy in this telescope, in good seeing. Nearby Rigel was an easy split, though.