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2021 Lunar X Predictions (start times)

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#1 67champ

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Posted 31 October 2020 - 09:46 AM

2021 Lunar X Start Times using -.90 Sun alt over the “X” location (LAT -24.9/LONG .9)

 

Jan 20 1831 UT
Feb 19 0830 UT
Mar 20 2209 UT
Apr 19 1115 UT
May 18 2341 UT
Jun 17 1133 UT
Jul 16 2302 UT
Aug 15 1028 UT
Sep 13 2208 UT
Oct 13 1016 UT
Nov 11 2303 UT
Dec 11 1230 UT


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#2 Astroman007

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Posted 31 October 2020 - 10:04 AM

Thank you for sharing.



#3 67champ

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Posted 22 November 2020 - 09:11 AM

Thanks Martin.  It's one of the few astronomical things I do these days (make these predictions and promote Lunar X and Curtiss Cross viewing)..  

 

I beat beggarly to the punch this year.  LOL

beggarly, if you have time maybe you could post your timings for a fully formed "X" and see what the difference in time is...

 

dana t



#4 Dave Mitsky

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Posted 22 November 2020 - 12:27 PM

Thanks, Dana!



#5 beggarly

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Posted 24 November 2020 - 05:02 AM

Predictions calculated with LTVT. https://github.com/f...i/LTVT Download

 

Searching for Sun Angle = -0.9000° over feature at 0.900°E   25.300°S
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
20/01/2021  18:26:01   -0.9000   91.5976   357.603  -1.059    1.476   5.101     88.832   49.118    7.560  *+
19/02/2021  08:22:53   -0.9000   92.0856   357.395  -1.500   -1.874   2.325     85.309   46.047    7.554  *+
20/03/2021  22:01:49   -0.9000   92.0915   357.392  -1.506   -4.941  -1.016     82.329   43.458    7.487  *+
19/04/2021  11:07:44   -0.9000   91.6331   357.588  -1.092   -7.057  -4.157     80.489   41.866    7.359  *+
18/05/2021  23:34:50   -0.9000   90.8568   357.920  -0.390   -7.717  -6.299     80.161   41.581    7.191  *+
17/06/2021  11:27:56   -0.9000   89.9794   358.295   0.403   -6.757  -6.754     81.408   42.652    7.024  *+
16/07/2021  23:00:01   -0.9000   89.2284   358.616   1.082   -4.429  -5.202     83.973   44.872    6.905  *+
15/08/2021  10:28:05   -0.9000   88.7962   358.801   1.473   -1.273  -1.960     87.340   47.801    6.860  *+
13/09/2021  22:09:09   -0.9000   88.8023   358.798   1.467    2.110   1.965     90.816   50.835    6.887  *+
13/10/2021  10:17:39   -0.9000   89.2616   358.602   1.052    5.136   5.233     93.674   53.329    6.967  *+
11/11/2021  23:03:10   -0.9000   90.0647   358.259   0.326    7.192   6.777     95.304   54.749    7.075  *+
11/12/2021  12:28:11   -0.9000   90.9893   357.864  -0.510    7.741   6.239     95.365   54.806    7.198  *+

  * = Target feature on visible disk
  + = Azimuth of Sun within 5.00° of target (= 90.000°)

                      *** search completed ***

 

Attached File  LunarX 2021txt.txt   10.87KB   67 downloads

 

Earth viewed from Moon at the time when Sun angle is -1.0°:

 

 

Attached Thumbnails

  • Earth View0.jpg

Edited by beggarly, 24 November 2020 - 05:14 AM.

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#6 Tom Hoffelder

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Posted 24 January 2021 - 12:29 PM

What is the lowest magnification at which any of you have been able to discern the X?  I barely saw it at 17.5X in our 120mm f/5 refractor, but that was in daylight.  I have not tried lower powers with other objectives under night skies.

 

Tom Hoffelder  (rocksnstars)


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#7 67champ

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Posted 06 March 2021 - 08:37 PM

Tom, I thought I had done this with my Barska 10x50mm Focus Free Binoculars steadied my holding them up against a vertical Pole in the yard (after dark); but now you have me doubting myself....  LOL

 

dana t



#8 james7ca

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Posted 07 March 2021 - 12:54 AM

Thanks for the heads up.

 

Unfortunately, it appears that none of those events will be visible from California in a darkened sky (they are either all daytime or after the moon has set). The closest from my location would have been on Feb. 19 when the moon set at 12:15 AM PST and the event was near to 12:30 AM. But, I suspect that there are a few hours of leeway either before or after the above times.

 

Ideally, you'd probably want something around 2:00UTC or 3:00UTC during the winter since that would be early evening on the west coast. Then, during the summer you'd probably want something closer to 5UTC.



#9 Tom Hoffelder

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Posted 07 March 2021 - 09:45 AM

The X is easily visible in the daytime, so don't let that keep you from viewing it!


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#10 Stefano Delmonte

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Posted 08 March 2021 - 02:13 PM

Thanks to everybodywaytogo.gif

 

Ste



#11 james7ca

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Posted 10 March 2021 - 05:51 AM

I wanted to check on the accuracy of these values and also to see how much leeway there would be either before or after the prediction.

 

So, I used NASA's Scientific Visualization Studio to produce a series of lunar simulations on the "X" (note that the co-called "Lunar V" is also visible at around the same time as the "X" -- see my next post). I checked the event for Mar. 20 and captured the simulation at -2 to +5 hours from 22:00 UTC (the predictions show between 22:09 and 22:01:49).

 

It looks like the predicted times are pretty close, but I think it might be better to be a little late than early (23:00 UTC looks good also). Anyway, below are the simulations (based upon LRO elevation data). Remember to click on the below preview to see the larger size.

Attached Thumbnails

  • NASA Visualization Studio Composite March 20 2021.jpg

Edited by james7ca, 10 March 2021 - 05:53 AM.

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#12 james7ca

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Posted 10 March 2021 - 06:02 AM

I also checked the NASA simulation with an image that I took in 2016 and it looks like the simulation is quite close to reality. Here is a series that shows my image (taken with a Stellarvue SV80ST2) and the simulation by NASA (the simulations can only be done on the hour). I'd say the simulation (also known as "Dial-A-Moon) is within 30 minutes of being exactly the same as my image. You can also see the "Lunar V" further to the north of the "X" (close to the top of my image) and I think the "Lunar V" is better seen AFTER the peak of the "X" (so, again being somewhat "late" on the "X" may be a useful thing).

 

In any case, if you want the best phase of either you should definitely use NASA's site. 

Attached Thumbnails

  • Lunar X and V Nov 6 2016.jpg

Edited by james7ca, 10 March 2021 - 06:04 AM.

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