On the evening of Valentine's Day, the San Jose (California) Astronomical Association held its monthly first-quarter public star party at Houge Park, a suburban site in south San Jose. This site is reasonable for giving passers-by a view of the basic celestial stuff, but experienced observers often end up looking at the Moon. I had a chance to observe several interesting features, and to compare several interesting telescopes.
One member had a nice Astro-Physics 130 mm f/8 set up. I took a glance through it and was delighted to find well-placed a feature in which I have a personal interest -- the small crater Burnham, just southeast of Albategnius, on map #45 of Antonin Rukl's Atlas of the Moon. Readers of the fine print in Sky and Telescope may recall that I once chanced upon a sunrise ray emanating from Burnham's west wall. This was the first view I had had of the area in good lighting conditions since I found the ray. The 130 mm did a nice job of showing the fine break in the crater wall -- just about under the "h" of "Burnham" in my Rukl -- through which the ray shines, at 148x. A six-inch f/8 Dobson, using a Cave Astrola optical tube assembly, showed the crater almost as well, at 181x. Even my 63 mm "Baby Brandon" refractor gave an acceptable view of the area, at 88x. The Burnham ray is due for a favorable apparition for parts of North America in March, I intend to see if I can observe it again.
Later the seeing steadied, and I was able to use the 130 mm again to study some of the delicate rille systems not far from the terminator. The Ariadaeus and Hyginus rilles were easy (Rukl map 34), and even the Triesnecker rilles (map 33) showed well, still at 148x. Further north, the Fresnel and Bradley rilles were not difficult (map 22), and I was delighted to see a very fine system of rilles that trails south and east from Archimedes, so tiny that Rukl does not show them well. However, I could not see the rille that winds along the floor of the Alpine Valley.
An Orion 90 mm f/11.1 refractor lay at the far end of the row of telescopes; this newcomer from Taiwan had excellent optics; it, too showed the fine rille system south of Archimedes, at 111x, though the view was not as good as in the Astro-Physics. I am pleased to see that this little import is a comer, too bad the mounting is not better thought out -- the control cables are inaccessible from many positions of the eyepiece.
I was too tired to stay late, but it is always nice to review the geography of the only other world whose geography we can see in small telescopes.