Lunar session on the Western rim

[SwiMatt]

This was my first "serious" lunar session where I searched for specific targets, out of the Lunar 100. This was also my first lunar session with the aid of the Duplex Atlas. With an observing list dedicated to the Moon, along with a good atlas, I think that lunar observing could quickly become a favorite of mine (if it isn't already).

I set my alarm at 4.30am and woke up to a beautiful barely waning Moon and no clouds, and I sat down on the balcony where I had set up the telescope before going to bed. The seeing was quite good, as the surface took my Mak 127 with barlow and 9mm quite well (that's 333x). However, I find such magnification a pain to use with a manual mount, so I stayed between 58x and 166x during most of the session.

My plan was to go through my Lunar 100 for objects around the Western rim, starting with L10 - Mare Crisium. What's really cool about Mare Crisium is that in any conditions it looks well defined and it's impossible to miss or confuse - like some other maria are. Its flat surface feels soothing to the gaze, but still offers a few craters to add variety. 

I moved on to crater Petavius (L16), but did not increase the magnification to search for the rille that goes through the floor. Instead I took my sweet time (about 1h) to sketch the area between Petavius and crater Langrenus, North of it along the terminator. It was the part of the session to which I was looking forward the most, as I hadn't sketched the Moon since before the summer. Petavius and Langrenus look quite similar, with terraced rims and both with a central peak. In between the two, a few craters form interesting shapes and shadows over an otherwise flat surface.

At 6am I went to the border between Mare Crisium and Mare Tranquillitatis to search for craters Proclus (L12) and Taruntius (L31) but to my surprise it was very difficult to orient myself on the Atlas. That is, until I realized that the map is of course oriented with the N-S axis vertical, but that does not correspond to the vertical of my horizon! After finally learning my way around, I found my targets with ease. Proclus shows distinct rays around it, and once I knew which one it was, it became impossible to miss as it's very prominent, just East of Mare Crisium. Taruntius, a young crater with a fractured floor, was slightly more difficult as it's not very prominent right now, but with it's smaller crater on the rim it also became obvious after a bit of looking. 

At this point dawn was upon me and I could basically follow the chart without a light. I went for another object in the area, craters Messier and Messier A (L25) - the result of a body that ricocheted on the surface upon impact. Rays moving away from the latter crater let one guess the direction of the impact. It is a small feature with plenty of details to look for and I look forward to cranking up the magnification on it.

At 6.30am, later than I normally wake up, I picked up my stuff and got back inside, then took out the dog. I just got to work now, and the Moon is still on the sky, and somehow it feels more like an old friend than it did before.