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cloudsweeper

110km Long Cliff Plus Fainter Crack: Good Now

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I specifically wanted to see these features which are favourably placed at this part of the lunation.

4.45pm, 8SE, Moon just past first quarter, in the SE, handily above rooftops.  Sky fairly dark, so Moon bright when not behind clouds, but I only wanted a brief window.  Luckily, I soon got a longer one, as the clouds mostly cleared.

Target 1: Rupes Recta, known as the Straight Wall (but it is actually a 400m high cliff or scarp (at a 40deg slope).  It's on the eastern edge of Mare Nubium, and runs roughly N-S.  Best viewed just after first quarter (now) -when it appears as a dark line, or around third quarter - when it is light.  M. Nubium was in view, with Bullialdus to its west, near the terminator.  Over to the eastern side, I spotted the "Wall" - a dark, very thin, yet clear gash between the small crater Birt and the larger Thebit (with a Birt-sized craterlet bang on its western rim).  I was using x135 from a Meade Plossl.  Then x169.  Birt had a tiny pit on its western edge.

Target 2: To the west of the "Wall", roughly parallel with it, runs the shorter Birt Rille (crack).  It rises from the western side of Birt, curving slightly westwards on its course.  After Rupes Recta, this was hard to spot; a real challenge.  (Too far from the terminator??)  I dropped down to x135 again.  With fine focusing, and patience waiting for good moments of seeing, the crack popped in and out of view, with the northern section being a little clearer.  Less noticeable at x102.

I finished for my meal after 45 minutes, but felt really satisfied at having achieved the two goals, especially as the second was elusive, and certainly not apparent when just scanning round Luna's surface.

Thanks for reading,

Doug.

 

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Very nice. I spend more time looking at rilles than craters. I especially like it if it's a challenge. It seems I would have enjoyed your session very much.

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Cloud sweeper. I was first light last night with a 150 pds. About 20:00hrs Rupes Recta was astonishing, the equal small craters either side symmetrical.

Been a while since I observed Lunar, need to do more, so easy to forget it is in reach.

Marvin

 

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Nice report Doug - one of my favourite areas of the lunar surface to observe :icon_biggrin:

I snapped the rather basic pic below with my mobile phone at the eyepiece of my 12 inch dob a while back which I think shows the two features that you describe so well:

 

stwall.jpg

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^^^^ Thanks John - don't know about "rather basic", I reckon that's a very good shot with only a 'phone! - it shows all those features well!

Doug.

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Unfortunately here in Dronfield after 3 nice clear nights, conditions were not good Thursday and Friday of this week, so I've missed the opportunity of a good view of the Straight Wall this lunation, but it will be well placed for the next few lunations with the waxing gibbous moon gradually increasing in altitude in the evening sky.

I attach a photo taken some years ago through my 14in Newtonian using eyepiece projection, and with my old Pentax digital SLR (which did not have live view), I would probably get better results with my Canon 6D. 

 

Moon_12 strghtwall aa.jpg

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Here is another perspective of this fascinating area. This image was taken from the Apollo 16 Command Module in 1972:

image.png.c889dc5bb51696a0a0194f45e433348c.png

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30 minutes ago, John said:

Here is another perspective of this fascinating area. This image was taken from the Apollo 16 Command Module in 1972:

image.png.c889dc5bb51696a0a0194f45e433348c.png

Jeepers. That is one hell of a photo from all sorts of perspectives. 
 

John

 

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5 hours ago, John said:

Here is another perspective of this fascinating area. This image was taken from the Apollo 16 Command Module in 1972:

image.png.c889dc5bb51696a0a0194f45e433348c.png

John, done us proud right there. Can’t stop comparing this picture with the over head from Johnturley. Never noticed the deformation in the right crater wall.

Enlarged the overhead image to see the crater nearest to the close end of the wall. Doesn’t really show up on the overhead.

Next opportunity I have a mission to try and see that magma rille to the right of the central crater in this shot. Can’t imagine what it looked like to the naked eye.

Marvin

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