Hitchhiker's Guide to Rukl Chart II

Northeastern Limb (Akkana)

I wrote an observing report, including a sketch, on trying to find my way around the northeastern limb of the moon during the northern/eastern libration of 12/14/97.

Mare Humboldtianum (Akkana)

During favorable librations, Mare Humboldtianum shows a nice double-ring structure, like a smoothed and weathered Orientale. Its floor has interesting changes in tonality; it really does look like Rukl's drawing. The near side of Belkovich shows up as a wall intruding into the northern end of Humboldtianum.

Mare Humboldt (Bill O'Connell <imbrium449 _at_ sprynet.com>)

Like Dave, I noted the outlying ring of the Mare Humboldtianum basin, seen in this video still. It appears as a distinct ridge between Endymion and the mare. I agree its a rare view. Compare Humb1.jpg for a view under almost identical lighting taken last month that doesn't show it at all.

Mare Humbolt (Steve Coe <scoeandlross _at_ sprintmail.com>)

This small Mare is at the edge of the Moon and is very fore-shortened. The floor is flat with 12 little craters and 5 mounds seen. This large flat area has low walls with a little terracing. There are several white markings seen across the floor, mostly from PA 300 to PA 135.

Mare Humboldtianum (Brent Hutto <BHutto _at_ InfoAve.Net>)

0200Z Nov 12, 2000: On the northern side of Humboldt, there was a peak rising way up from the limb of the Moon. It is shown in Rukl #7 in profile view, stretching from 58 degrees to 60 degrees north latitude. What was interesting was the foreshortened crater which has that peak as it southern wall (separating it from the Mare). It is labeled "A" in Rukl, I suppose that means Rukl's name for it would be Belkovich A.

The entire rim of the crater was brightly lighted with its floor in amazingly dark shadow. There was a thin thread of dark shadow separating the lighted back rim of the crater from the peak that demarks the crater from the Mare. So it gave the effect of a narrow, bright cantelever extending from the north toward that huge peak on the south but not quite touching it. The apparent depth of the crater due to the contrast was so realistic you could almost imagine falling into the eyepiece if you stared at it long enough.

Belkovich (David North <d _at_ timocharis.com>)

See chart 7 for a discussion of Belkovich and Mare Humboldtianum.

Hayn (Akkana)

Hayn has a tall central peak -- lovely at sunset during a favorable libration, when the central peak rises out of the darkness of the crater into the last rays of the setting sun.

Nansen (Akkana)

One of the most prominent large craters in this libration zone.

Compton (Akkana)

Mentioned in The Once and Future Moon as a good example of a medium-sized crater with a ring mountain surrounding an odd, hooked central peak. Probably only marginally visible, requiring an extreme eastern libration. (I haven't seen it yet.)