Observing Report – Mare Vaporum – 2013-12-12

I am pretty sure i was observing on the 12th, although it may have been Dec 11. It’s  important because the phase of the moon plays an important role in what can be observed on the lunar surface.  I do know it was clear and pretty $#^&* cold with temperatures below -20c at 10pm.

Pyroclastic formation south east of Mare Vaporum

Pyroclastic formation south east of Mare Vaporum

I had found statements that the dark pyroclastic formation to the south east of Mare Vaporum was observable even at a full moon. I had just completed my image of that area taken with a lunation of 7days, so was keen to test that statement. I grabbed the 70mm Telvue Pronto, which was already on the camera tripod, and observed from the front porch at 10pm to see if i could find the “dark spot” below Mare Vaporum.

Using the 70mm scope and a 5mm Hyperion yields a magnification of 96x and a real FoV of 42′. So the whole moon didn’t quite fill the field of view but provided enough magnification that i was hopeful of seeing the details i was after. The seeing was actually quite poor despite the seemingly very transparent skies. I was also observing at about 10pm so the moon was high in the sky and due south which should have been ideal. I think the cold winter air gives the impression of being clear, but the seeing (stability) is generally poor in these conditions.

Mare Vaporum was easy to spot. As well 4 dark “spots” to the south east were clearly visible. The one furthest east is the large crater Julius Caesar. Just west of that is the crater Boscovish. Then there are two dark spots that together with Boscovish form a line going south west. I presume the two additional spots are the craters Hyginus Z and Hyginus S.

As for the pyroclastic formation, i think with a little stretch of the imagination i did see it. But the seeing was poor and the magnification and resolution of the 70m Pronto was probably marginal for that task. As well, the camera tripod was affected by the stiff breeze making it hard to get a stable fix on the object of interest.

I will have to try again with the HD11 on the motorized CGE Pro to be able to definitively say that the dark formation is visible past the 1st quarter moon.