24th June C8 session - bagging Lunar 100 objects

[Paz]

I set up for a session on the moon this evening not expecting the best of views but just being out in nice warm weather. I recently resolved to change some of my observing habits so I was armed with a sketching pad which I have been using more often lately, and I resolved to identify and properly observe more new objects using the Lunar 100 list. I found a useful webpage of the Lunar 100 with a map of where they are plus a list describing/naming each item under the map.

Lunar 100 (wilmslowastro.com)

I've been going back through my observing notes and ticking off what I have seen already but this is my first time deliberately picking objects on a list for viewing rather than I view what I like which might or might not be on a list. I picked the Mare Serenitatis area as the terminator was just about past it so I thought anything there would be a good start. I was set up with a C8, 1.7x GPC, binoviewers and 20,mm SLVs for 173x and was using an EQ5 for tracking, which meant I could easily concentrate on what I was looking at. The seeing wasn't perfect, and with thin cloud coming and going it varied constantly, but I was quite focused on getting some new targets so the seeing didn't really register much with me, whereas normally it would be a preoccupation dwelling on the seeing conditions.

Sulphicius Gallus dark mantle (Lunar 100 - Number 71) - it sounded like a villain from a Harry Potter book but it is in fact a Lunar dark feature from volcanic sources. I had a read up and apparently it is rich in titanium, iron, and volcanic glasses. I spent a long time on this and did a dodgy sketch which I won't inflict upon the internet. The dark mantle was vaguely apparent from the beginning but it was really obvious by the time I finished sketching having concentrated on it. It's now going to be one of those features that really stands out every time I pass that area by.

Bessel Ray (Lunar 100 - Number 41) - a white ray from impact ejecta but the source of this is not known for sure. I could see the thinner ray north of Bessel more clearly than the broader ray south of it but I don't think it was ideal lighting to see this now, I think at full moon it will be most obvious, and whilst I didn't know that it is called this, I am sure I have clocked this previously at full moon. This is one of the reasons for using a hit list - how many things have I looked on the moon at where I missed out on appreciating it through not knowing what it really was. Every DSO I've observed I know what it is quite well, but there's so much on the moon that it's easy to pass over the things that you see.

Linne (Lunar 100 - Number 82) - a classic small crater with bright ejecta all round, I've read about this in the past and I'm sure I've seen it before. According to the Lunar HD app the terminator has just passed but the Maria floor here was still dark. The lip of Linne was only just lit and confirmed by its relationship to Linne G/H/F/B/A that stitch a line across the Maria nearby. I went up to 10mm SLVs for 345x just to be sure. The view was poor, this higher magnification plus the moon getting lower and the cloud getting thicker made it like watching an old black and white tv with bad reception, but there was no doubt about spotting Linne.

Valentine Dome / Linne Alpha (Lunar 100 - Number 89) - a volcanic dome with a rille running through it. I couldn't see this at all but looking it up now I can see I was looking south of Linne when I should have been looking north  plus it looks like it might be a tough target when the lighting isn't favourable and I am not sure if the terminator was far enough over to see it at the time I was out. I'll have to come back to this one.

In the end I was out for a coupe of hours, which is much longer than I usually observe, and the time flew by - always a sign of a good session.