by Akkana Peck
Wow, last week, we had several clear days in a row, and during first quarter! It was so nice to have a chance to get out and observe the moon again, after all the rainy weather we've been experiencing here in northern California.
Tuesday night (5/10 about 6am UT), I rolled out old Cave 6" f/8 Newtonian -- the first visit in a long time with an old friend from my childhood. The area around the Altai Scarp attracted my attention immediately, with a very prominent catena stretching from near Piccolomini toward Polybius E and through Polybius R. Nearby, there were many smaller catenae visible, running parallel to the more prominent one but composed of much smaller craters.
Catena Abulfeda looks not like a chain of craters, but more like a thin, very straight white line connecting one wall of Abulfeda to the opposite wall of Almanon. http://www.shallowsky.com/images/sketch/abulfeda.jpg
As usual, I didn't think to look for Tranquility Base until the moon was relatively low. It might have been fairly easy while higher in the sky, but by the time I thought to look and got my bearings, Armstrong was still fairly easy, but I wasn't convinced that I could see either Collins or Aldrin.
I always have trouble navigating in the area of Statio Tranquilitatis. I came up with a hint for myself the next time I try it: after finding Ritter and Sabine, find the large crater Maskelyne (spilling over to the next Rukl page, chart 36) to the east, and Moltke, between Ritter/Sabine and Maskelyne then southward. Moltke (Rukl chart 46) is easy to recognize because of its prominent white halo, even when near the terminator. Moltke makes it easier to recognize where Armstrong and Collins should be, and Rimae Hypatia, near Moltke, offers scale to find the site. Don't expect Rimae Hypatia to be as easy to see as they look in Rukl; I find them somewhat subtle, at least when near the terminator.
In the same general area, a stray comment from Dave led me to notice the wonderful "seagull" near Al-Bakri. "Seagull??" I said, puzzled, scanning ... then I saw it. Yes, it's a seagull! My sketch (http://www.shallowsky.com/images/sketch/seagull.jpg) doesn't do it justice, though I enjoyed sketching the lovely Promentorium Archerusia.
The following night, Wednesday, Klein, straddling the terminator at 5:45 UT, looked like it had an embedded crater in it, almost exactly concentric with the main crater. It was probably a trick of the light -- Rukl's sketch shows no such feature in Klein, just a curved central peak which might have looked like part of a concentric inner ring. There was a nice catena leading into Klein across the northwestern wall of Albategnius. Albategnius seems to be crossed by many north/south pointing rilles and catenae -- there's another very prominent one on its eastern wall. Perhaps these are secondaries from Copernicus, or even from Imbrium (though they're presumably younger than that)?
Walter was right on the terminator. We read about the Walter ray, but I don't recall hearing anyone describe how lovely early sunrise is in that crater. It's almost like a miniature Clavius, with its inner craters showing illuminated rims, then bits of the floor gradually shading in as the sun angle changes. I only made one sketch, an early view: http://www.shallowsky.com/images/sketch/walter.jpg. About an hour after the sketch (0800 UT), I looked for signs of a sunrise ray (though I believe the well-known ray in that crater is a sunset ray). Jagged triangles of dark and light showed along the western wall of Walter, but no sunrise rays were in evidence. However, a long, narrow ray was visible along the highlands north of Walter, in the vicinity of Regiomontanus and the north end of Deslandres.
