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Sunrise over Gassendi

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Paz    789

I set up the MC 127 and EQ5 for a quick look at the moon this evening. It was not long after 9:30pm so there was some daylight as well as hazy cloud coming and going. I have not had much luck with clouds recently, and my last session was cloud dodging glimpses of Jupiter and the Moon (although I did get a good view of the Straight Wall).

My scope was cooled but I had garage roof heat as well as the cloud and some daylight to contend with so the views were not as sharp as they could be.

I ended up focusing on Gassendi because the sunlight was just clipping the mountain tops in the centre of the crater. At first three small points were visible, then over time two of the peaks became one line. As the sunrise dropped lower into the crater it started clipping other raised bits of the crater floor.

The collapsed crater wall on the terminator side was very well lit. A very bright small crater on the north end of the collapse was prominent. The southern end of the collapse had a shadow in the middle of it I suppose where there's a rim or a dip of some sort. What also caught my eye was it looked like the sunlight was flying through a gap or maybe going just over the top of the crater wall and lighting up a ridge just outside of the collapsed wall, which showed up as a thin short white line that grew a little bit in size as I watched it over time.

I ended up completely focused on watching the sun rise inside the trailing rim of the crater and watching the ridge just outside, the sun lighting up the higher ground first, and must have spent 45 minutes looking at just this. I had RA tracking on and my observing chair so I didn't have any work to do keeping it in view and didn't have to put up with any awkward positions - I could just look.

I also noticed nearby in Mare Humorum some faint lines that remind me of high tide water marks left in sand on the beach.  I've seen nicer ones near Sinus Iridium in the past and so had a quick look over there but the sun was too high over there by now.

The views were a bit confusing for me as having spent a couple of years using RACI diagonals but I'm starting to use a Takahashi prism diagonal more often (I have not been a fan of flipped images in the past as I find objects manually and RACI helps but the better quality of the views with the Takahashi is growing on me) and if you put the way that flips the image left/right together with angling the diagonal sideways so I can look straight ahead the orientation of the image is all over the place compared to how it really looks!

I don't do photography but as the cloud started to thicken up and I was ready to pack up I took a quick photo with my phone for the memory. It's rubbish compared to how it looks by eye but it will remind me of this session which was one to remember. I think this was with the 10mm SLV so 190x.


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kerrylewis    1,445

What an evocative report. I've never been much of a moon observer (not sure why) but I did notice recently how great the views were in my recently acquired Tak (also with a Tak prism). The contrast seemed greater and the shadows blacker. This and your report may get me interested again. Time to dust off the Lunar 100?

Thanks again for  a lovely report 



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Astro Imp    2,933

Thanks for posting a most interesting report, IMO the moon is a fantastic object to observe, there's always something different to see.

Thanks again, I look forward to reading your next report.

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Nyctimene    448

Gassendi, IMO, is one of the finest moon craters. I like to observe the complex rilles system on it's floor. When I was out Wednesday evening with my 8" f/4 traveldob, and the new 5,1" Heritage to compare them both, I took the small craters Gassendi N and M as test objects, as well as the trapezoid rilles frame around N. The 8" showed all features readily at 180x, the 5,1" Heritage showed N and the more prominent southern rille, but M just for some glimpses. (By the way, the 5,1" has got really excellent optics and a quite decent Dob mount - for an incredibly low price.)

Always something to observe on the moon - and no worries about streetlights or dark adaption!


Edited by Nyctimene
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Tyson M    743

A fine report indeed.

I do love me some lunar viewing. Straight wall and Gassendi are two of my favorites for sure. Even with the 80mm refractor and porta II, such a treat. 

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