Moon - 13th September 2016

[Paz]

I had what turned out to be a very enjoyable look at the moon last night and one worth remarking on.

I was out with my 127 Maksutov on an EQ5. I made a point of keeping it simple so only a Telrad to get to the moon and no RACI finder set up (I would end up getting distracted trying to find other stuff if that was fitted). I settled at the start on one eyepiece and one filter and stuck with that for the whole session so there was no workload/hassle regarding eyepieces and filters, and also no maps, computers, motors, batteries, cameras, leads, dew heaters, phone apps, etc. This resulted in a really good session just focused on the target and thinking about what I was seeing with no distractions, reminding me of the sessions I had back when I began observing with binoculars.

I had a 17mm plossl, a ND0.9 moon filter, and an erecting prism (I like things the right way up or flipped all the way around like a Newtonian - flipping N/S and not E/W I don't like!). I don't normally use filters but thought I'd give one a proper try for a whole session. So this was a 112x magnification and 28' field of view set up. I had tried out some other options over 200x but they were to noisy. I put my EQ5 down pointed roughly north - there was no need to be particularly accurate. I didn't put the scope out earlier to cool down and had to observe across rooftops so quite a bit of moving air but with the low-ish magnification that didn't matter much. I thought the seeing was fundamentally pretty good (but that's my amateur assessment!).

Starting in the North there was a crater to the right of Anaximenes with a shadow from its eastern rim hitting its floor that looked interesting. This far north I like finding shadows that you are almost seeing from the side rather than from above. I could not work out afterwards exactly what this was as the lighting of my maps is different. I'll be trying to find it again next time around and work out what it is.

I recognized Clavius and Schiller in the south even though both were fully lit away from the terminator, a good sign that I'm starting to remember something(!).

The west edge of Schickard was on the terminator, looking very big. Gassendi was benefiting from a good terminator position.

I spent some time on Prinz and the Harbinger mountains before ending up on the Aristarchus and Herodotus area. I didn't realise this was Aristarchus until checking back afterwards. The shadows and light meant Aristarchus didn't look crazily bright like it usually does. I noticed Schroters Valley which I had not noticed before. I was pleased to read afterwards that this feature is between 3-6km thick, and interested to know it is thought to be a source of the lava flows that filled oceanus procellarum. I noticed what looked like  a mound north of Aristarchus but it looks much flatter in maps than it did directly, and I didn't notice (or didn't remember) a couple of craters on it (e.g. Vaisala which is 8km across) which I found on maps afterwards.

My last look was back at the top where I started. I found the same crater/shadow to the right of Anaximenes and felt sure I could see the same shadow was now shorter as it was "sunrise" at that point on the Moon. I was wondering what it would be like for people working there in the future. I guess you might be at the bottom of a crater in pitch black and then sunlight would light up the crater rim above you before the sum bursts out over the rim onto the floor directly and the temperature swings from super cold to super hot!

I think on reflection the filter didn't enhance the views but to be fair I think it did make for less eye fatigue observing something so bright for a long period of time.

Looking back this was a good session with a few setting up short cuts to make it a minimum of hassle.

Small errata for the historical record(!) This was the 13th September, not the 14th. Title amended also.