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Purbach Cross (Lunar X) - Sunset Viewing Project

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#26 Magellan

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Posted 05 January 2013 - 12:55 PM

I redid the image, I think this is better, is my description right? I am a DS Imager starting to become a Lunatic ;)

Telescope: Orion 8" F4 Newt
Mount: CGEM
Camera: Astro Modified Full Spectrum Canon XSi
Filter: Astronomik CLS (was already inserted as a clipin)
Date: January 4th, 2013
Time: 0652AST
Location: Enfield
Captured with BackyardEOS
Frames: 1425/1500

I have included insets this time of closeups of the two features captured on the early morning of January 4th.

The Walther Sunset Ray is the setting sun is peaking through peaks of a mountain on the moon thus illuminating only a small portion of the crater.

The Pseudo X is the sun setting on the moon only illuminating the peaks of the mountain. This is called a Pseudo X because Werner X (The same effect on the rising sun side of the moon, First Quarter, is in complete darkness) this X is not in complete darkness making it less obvious as the surrounding area is partially illuminated.

Posted Image
MOON_100iso_06h52-1425Frames by AstroJeff, on Flickr

#27 edosaurusrex

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Posted 05 January 2013 - 01:15 PM

The shadow of Walther's peak can be seen on the crater wall!

#28 Dave Chapman

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Posted 05 January 2013 - 02:14 PM

Hey man, that's how we move this project along! I 100% agree with your re-calculations, although I use a spreadsheet tool. Unfortunately, I do not seem to be well-placed for observing this event for the rest of the year. In the wrong hemisphere, I guess! That's how it goes, with the X, I find.

Dave XVII


After reading Dave's report I have revised the Sun Angle so the Sun is at 1.5deg. The 1deg I reported for the first set of predictions was an error. The actual Sun angle in the program was 0.5deg (I'm so ashamed)

REVERSE WERNER X PREDICTIONS FOR 2013
MMM DD HHMM UT

FEB 02 2324
MAR 04 1337
APR 03 0320
MAY 02 1619
JUN 01 0431
JUN 30 1604
JUL 30 0316
AUG 28 1427
SEP 27 0200
OCT 26 1412
NOV 25 0314
DEC 24 1707



#29 Carol L

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Posted 05 January 2013 - 02:50 PM

In your photo, the classic X (what remains of it) is just north of that (see Magellan's photo).


You're absolutely right Dave - at a glance, i thought it was the Purbach Cross. I'd apparently seen the pseudo-X in the past, it's on the bottom half of the pic in my original post. But it went unnoticed at the time because i was concentrating on the intended target.

Here's something interesting - on the upper sunrise portion of my pic, i see a black pseudo-X formed by the shadows of Werner's western wall and the inside of Regiomontanus' eastern wall. :cool:

#30 edosaurusrex

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Posted 05 January 2013 - 02:51 PM

Dave!

Hopefully, one of the small group of people that are looking for this will be on the other side of the world.

You can see what I call the "Cat's Paw" (Walther central peak area) in the inset of Jeff's latest photo.

Ed

#31 Carol L

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Posted 05 January 2013 - 02:59 PM

Thanks for the updated info, Ed! :grin:

#32 thewheel

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Posted 07 January 2013 - 01:16 PM

Thanks, Carol.

I made some little mistakes, tried to fix them on this one ,
used Virtual Moon Atlas and the LPL Lunar and Planetary Website to get some annotated real photos from a lunar satellite:

http://www.lpi.usra....l?REGIOMONTA...

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#33 Carol L

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Posted 07 January 2013 - 03:28 PM

You're welcome. :) It looks like your Mystery Top is the inside of la Caille's NE rim. Also, there are 2 very small points of light 'just' above the top of the pseudo-X that are most likely the two southern tips of Purbach X's arms.
(BTW, i love your 'Uncle Walter' label. :lol:)

#34 67champ

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Posted 09 January 2013 - 06:54 PM

Great idea Carol; nice job everyone. :refractor: :refractor:

dana t

#35 67champ

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Posted 19 February 2013 - 08:16 PM

Dug this out of the archives... ah, This "X" is a little more interesting than I remembered it... February 9, 2007 10:10 UT.

dana t

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#36 67champ

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Posted 19 February 2013 - 08:38 PM

Resized...

dana t

#37 edosaurusrex

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Posted 19 February 2013 - 09:54 PM

Dana et al,
09 FEB 2007 at 1932 UT would have been the prediction for a 1.5deg Sun elevation. So that puts the photo at an elevation of about 6 degrees.

Ed

#38 67champ

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Posted 20 February 2013 - 08:49 AM

Co-long of appprox. 172.79 with a sunset illumination fraction of approx. .596 for my photo Feb. 09, 2007.

dana t

#39 67champ

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Posted Today, 08:01 AM

Found a great photo of this in a advertisement in an old Sky & Telescope magazine.  I will try to post this later this week...

Dana T








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