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Alexander Lunar Sunset Light Ray

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#1 Dave Mitsky

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Posted 10 August 2020 - 02:47 AM

The last celestial object that I observed from the Naylor Observatory this morning was the waning gibbous Moon.  I was scanning along the terminator with the 17" f/15 classical Cassegrain housed in the French Dome at approximately 5:45 UT (1:45 a.m. EDT) when I noticed that a lunar crater light ray was taking place in the crater Alexander.  The ray was quite narrow when I first noticed it.  I took a number of hand-held afocal iPhone images of the ray and continued to observe it and the Moon for another 20 minutes before I began closing down for the night.
 

Information on the Alexander lunar light ray and other rays, including predictions of occurrences, can be found at http://www.lunar-occ.../alexanderp.htm and http://www.lunar-occ...o/rays/rays.htm

 

I'll post a few more photos later today.

 

Monday afternoon: For some reason, most likely mental fatigue from lack of sleep, I confused Calippus with Alexander.  I should have waited until I got some sleep to post my report.  The Alexander lunar ray was one that I reported back in 2003!

 

http://www.lunar-occ...s/alexander.htm

Attached Thumbnails

  • Alexander Lunar Light Ray August 10 IMG_6356 Processed Rotated Labeled CN.jpg

Edited by Dave Mitsky, 10 August 2020 - 01:18 PM.

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#2 Orion92

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Posted 10 August 2020 - 04:59 AM

Very cool and thanks for sharing, Dave. The light ray looks like the hour hand on a clock to me! Calippus looks to have a fairly flat floor, but I guess there must be some raised portions to generate this ray?


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#3 beggarly

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Posted 10 August 2020 - 07:29 AM

You observed at approximately 5:45 UT (1:45 a.m. EDT), but according to the EXIF information the photo was taken on 2020:08:10 at 04:00:43.

 

For this simulation in LTVT is used data from http://www.lunar-occ...s/calippusp.htm

8/10/2020  06:26:16    3.5232  268.7504   165.774   1.241   -1.465   5.498    105.126   63.561   20.537  *+

 

Alexander.jpg


Edited by beggarly, 10 August 2020 - 08:41 AM.

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#4 beggarly

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Posted 10 August 2020 - 09:18 AM

Simulation of observation: http://www.lunar-occ...ys/calippus.htm

 

2000_08_21.jpg

 

Simulation of observation: http://www.lunar-occ...s/alexander.htm

 

2003_07_20.jpg


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#5 beggarly

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Posted 10 August 2020 - 09:22 AM

Predictions for the triple ray event in Alexander:

 

Lunar lighting conditions calculated for:  20/07/2003 07:00:00 UT

Searching for Sun Angle = 2.7253° over feature at 12.720°E   40.210°N
Moon librations, elongation and percent illumination calculated for a geocentric observer

                           Sun Angle       Sub-Solar Point     Librations                 Phase  
   Date      Time UT   Altitude  Azimuth    Colong    Lat.    Long.    Lat.     Elong.   %Illum.    Age
10/08/2020  04:26:39    2.7253  269.3196   164.759   1.240   -1.356   5.563    106.491   64.316   20.454  *+
 8/09/2020  16:30:18    2.7253  269.7267   165.022   1.551   -4.034   3.082    108.919   66.331   20.575  *+
 8/10/2020  04:41:52    2.7253  269.5894   164.933   1.446   -6.096  -0.189    111.008   68.041   20.737  *+
 6/11/2020  17:08:28    2.7253  268.9214   164.503   0.936   -7.002  -3.537    112.249   69.044   20.901  *+
 6/12/2020  05:56:01    2.7253  267.8946   163.840   0.153   -6.316  -6.035    112.190   68.995   21.034  *+
 4/01/2021  19:07:28    2.7253  266.8073   163.138  -0.675   -4.014  -6.742    110.672   67.762   21.119  *+
 3/02/2021  08:39:47    2.7253  265.9915   162.610  -1.297   -0.686  -5.169    107.981   65.548   21.152  *+
 4/03/2021  22:22:08    2.7253  265.6913   162.416  -1.525    2.722  -1.756    104.760   62.855   21.136  *+
 3/04/2021  11:58:24    2.7253  265.9786   162.602  -1.306    5.436   2.217    101.758   60.309   21.067  *+
 3/05/2021  01:13:15    2.7253  266.7463   163.098  -0.722    7.060   5.348     99.587   58.450   20.946  *+
 1/06/2021  13:58:02    2.7253  267.7664   163.757   0.055    7.421   6.781     98.622   57.620   20.790  *+
 1/07/2021  02:12:38    2.7253  268.7653   164.402   0.817    6.484   6.363     99.002   57.950   20.639  *+
30/07/2021  14:04:00    2.7253  269.4883   164.868   1.369    4.396   4.431    100.660   59.376   20.533  *+
29/08/2021  01:43:26    2.7253  269.7477   165.035   1.566    1.520   1.545    103.329   61.653   20.495  *+
27/09/2021  13:24:34    2.7253  269.4616   164.851   1.348   -1.615  -1.663    106.563   64.377   20.523  *+
27/10/2021  01:21:57    2.7253  268.6853   164.350   0.756   -4.406  -4.540    109.779   67.039   20.595  *+
25/11/2021  13:49:13    2.7253  267.6184   163.662  -0.057   -6.285  -6.418    112.338   69.118   20.691  *+
25/12/2021  02:55:11    2.7253  266.5673   162.983  -0.858   -6.854  -6.686    113.666   70.182   20.800  *+

  * = Target feature on visible disk
  + = Azimuth of Sun within 5.00° of target (= 269.500°)

                      *** search completed ***

 

2020_08_10.jpg



#6 Dave Mitsky

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Posted 10 August 2020 - 12:34 PM

You observed at approximately 5:45 UT (1:45 a.m. EDT), but according to the EXIF information the photo was taken on 2020:08:10 at 04:00:43.

I don't know how to explain that.  I took the photo at 1:44 a.m. EDT.  I actually first noticed the ray when I looked at the photograph on my phone.

 

Thanks for alerting me as to my error.

Attached Thumbnails

  • Alexander Ray Time IMG_5775 CN.jpg

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#7 Dave Mitsky

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Posted 10 August 2020 - 01:17 PM

Very cool and thanks for sharing, Dave. The light ray looks like the hour hand on a clock to me! Calippus looks to have a fairly flat floor, but I guess there must be some raised portions to generate this ray?

In the foggy state I was in at the time, I got the two craters confused.


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#8 Dave Mitsky

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Posted 10 August 2020 - 03:51 PM

Here's another photograph.

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  • Alexander Lunar Ray August 10 UT IMG_6369 Processed Rotated CN.jpg


#9 Dave Mitsky

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Posted 10 August 2020 - 03:57 PM

And one more...

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  • Alexander Lunar Ray August 10 UT IMG_6436 Processed Rotated CN.jpg

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