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The "Maurolycus Beam" on July 23rd, 2019

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#1 astrolexi

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Posted 27 July 2019 - 04:45 PM

I happened to capture the "Maurolycus Beam" on July 23rd, 2019 with my C8.

The image was captured at 03:34 UT with an ASI 178MM, a 0.63 reducer and a 685nm IR pass filter.

500 frames stacked.

 

I don't know if this is a feature which is described elsewhere.

Maybe it is caused by a narrow valley in the western rim of this crater together with the shadow of the central peak?

 

Obviously there is always something new to discover on the lunar surface...

 

Best wishes

Klaus

 

 

Attached Thumbnails

  • Maurolycus_Beam_053418_230719_IR_2.jpg

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#2 Lindhard

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Posted 27 July 2019 - 05:51 PM

It is mentioned here

 

http://www.lunar-occ.../maurolycus.htm


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#3 flt158

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Posted 28 July 2019 - 07:43 AM

Gosh! What a superb beam that is in the centre of the 114 kms crater Maurolycus!

It's seriously spooky -straight from a science fiction movie. 

 

I am also greatly admiring the barely visible raised rim of the adjoining crater Barocius (82 kms).  

 

Excellent image, Klaus! Thank you

 

Kindest regards, 

 

Aubrey. 


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#4 astrolexi

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Posted 29 July 2019 - 09:50 AM

Thank you Aubrey for the kind words!

 

And thank you Lars for the link to David Kingsleys beautiful description of the Maurolycus Lunar Ray!

"...like an island lighthouse in the middle of a dark ocean..." and "...a pretty reversed S of light...".

It fits exactly to this image I captured a few days ago.

 

I don't know if David Kingsley got an answer to his question "if anyone else has observed or photographed this

area around similar illumination conditions".

If not, here it is...with a little delay of nearly 19 years.

 

Best wishes

Klaus


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#5 Lindhard

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Posted 29 July 2019 - 02:55 PM

Maybe the ray is only visible every 18 years when the conditions are exactly the same?


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#6 Dave Mitsky

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Posted 29 July 2019 - 03:19 PM

A list of the known lunar crater light rays can also be found on Rob Robinson's site.

 

http://www.lunar-occ...o/rays/rays.htm

My friend Tony Donnangelo and I were avid lunar crater light ray observers years ago.  Tony was very successful in discovering quite a few of them and I located a number of new crater light rays as well.
 


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#7 Dave Mitsky

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Posted 29 July 2019 - 03:30 PM

Maybe the ray is only visible every 18 years when the conditions are exactly the same?

Lunar crater light rays are far more commonplace than that.

Predictions for Maurolycus Ray events for the period 2015 to 2025 are listed at http://www.lunar-occ...maurolycusp.htm


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#8 stickler

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Posted 29 July 2019 - 06:01 PM

Thanks to Lars Lindhard for alerting me to this thread.

 

I really enjoyed seeing  a picture of the Maurolycus ray so many years after my initial visual report!

 

David Mitsky's table shows that the July 2019 observation occurred right on the schedule, based on the ray timing described back in September of 2000.

 

That's also a great listing of future times for anyone else who wants to see a beautiful play of light and shadow in Maurolycus on the moon.

 

-David Kingsley

(Still at Stanford and still observing many years later)

 

 

 

 

 


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#9 Tom Glenn

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Posted 31 July 2019 - 03:58 AM

That’s a nice image Klaus, and a very interesting topic.  Also, very interesting for Lars to locate that report from September 2000.  Coincidentally, the author, David Kingsley, is a professor at Stanford in the Developmental Biology department, and was a member of my thesis committee while I was a graduate student in that department.  Small world!  Needless to say, I was not expecting that when clicking on the link.  David, it was very nice to read your report all these years later, and to see you appear on the forum!

 

The beam in Klaus’s image looked wide enough to me that it should not be overly influenced by latitude changes in the subsolar point, as the axial tilt of the Moon is only approximately 1.5 degrees to the ecliptic.  Therefore, I would have thought the beam might occur at every sunset on Maurolycus.  The table provided by Dave Mitsky lists the events that occur within a 2 degree restriction of the Sun’s azimuth, and shows that only six such events occur in 2019.  If that restriction in azimuth is relaxed to 4 degrees, however, the event does occur at every sunset on Maurolycus, as shown in the table below.   The point chosen at which to calculate the solar illumination angle was approximately the western apex of the beam of light (as it occurred on September 19, 2000 at 08:10UT), and the times listed are within 10 minutes of those in Dave Mitsky’s table, but with the addition of six more events because of the relaxed azimuth restriction.   Note that for any given observer, not all of the events will occur with the Moon above the horizon.  

 

Maurolycus_predictions_2019.jpg

 

In order to check to see if this relaxed azimuth restriction has any effect on the perceived beam, I used the Lunar Terminator Visualization Tool (LTVT) software to simulate the illumination at each predicted event for 2019.  The results are displayed below as an animated gif.  Sorry for the poor quality, but the file needs to be compressed to under 500kb for posting.  The view in this simulation is not the view from Earth, but rather from a fictitious observer located directly over Maurolycus, so that the orientation of the image does not change due to libration.

 

Maurolycus_LTVT.gif

 

As can be seen in the animation, the beam does exist at each sunset on Maurolycus, although the changing azimuth of the Sun does affect the characteristics of the beam.  The beam sweeps slightly from north to south as the subsolar point cycles between its position 1.5 degrees below or above the lunar equator.  As the beam sweeps to the south (with increasing subsolar latitude), the beam intersects with more of the central peak of Maurolycus, and this restricts its width to the east of the peak.  The red and blue lines mark the sunset terminator, with the width corresponding to the angular diameter of the Sun, and you can also see how the orientation of the terminator relative to Maurolycus changes slightly with changing subsolar latitude.  

 

I looked through my files to see if I had any images of this event.  I did not, although I have an image that occurs approximately four hours prior to the event.  The image is from last year, and was taken on September 30, 2018 at 11:55UT. 

 

https://c1.staticfli...306daf4d4_o.jpg

 

Interestingly, this corresponds to a period of 18 years, 11 days, and ~4 hours after David’s observation from September 19, 2000 at 08:10UT.  This is just 4 hours short of a Saros cycle, which is used in predicting eclipses because of the nearly identical Sun-Earth-Moon geometry, but also corresponds to nearly identical illumination, phase, and libration patterns on the Moon.  If you locate and zoom in on Maurolycus along the southern terminator, you can see a set of opposing triangles, one illuminated on the west that will become the beam several hours later, and the shadow of the central peak to the east.  Although the terminator position in this image is several hours earlier than in David’s observation, this image of the Moon from September 30, 2018 is nearly identical to how it would have appeared on September 19, 2000.


Edited by Tom Glenn, 31 July 2019 - 04:09 AM.

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#10 frank5817

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Posted 31 July 2019 - 12:27 PM

Klaus, David and Tom,

 

Very nice posts on the sunlight floor ray of Maurolycus crater. I have observed this one in the past.

From the western states the Moon will be above the horizon for a view of this in September on the night of the 20th and a better view further to the East.

 

These rays make observing the changing  appearance of the Moon a joy.

 

Frank :)


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#11 astrolexi

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Posted 31 July 2019 - 02:46 PM

Thanks a lot to all the contributors!

The report, the links, the lists, the animation! All this is absolutely amazing and motivating!

 

I really learned a lot about the Maurolycus ray and - by the way - about how his forum works. Fantastic!

 

I hope that in the future someone will create a calendar where you just put in your planned observation time.

As a result, this calendar should show all features visible on the moon's surface. Even these nearly hidden lunar rays.

 

Thanks again and best wishes

Klaus


Edited by astrolexi, 31 July 2019 - 11:27 PM.

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#12 stickler

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Posted 02 August 2019 - 08:34 AM

Simply outstanding followup Tom, with many informative analyses and examples of lunar tools put to use!   

 

Great to hear from you, and I didn't realize your astronomical interests when you were in graduate school.  Did observing and imaging develop post-myelination? 

 

David Kingsley



#13 Tom Glenn

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Posted 03 August 2019 - 01:18 AM

Simply outstanding followup Tom, with many informative analyses and examples of lunar tools put to use!   

 

Great to hear from you, and I didn't realize your astronomical interests when you were in graduate school.  Did observing and imaging develop post-myelination? 

 

David Kingsley

Thanks, David.  Yes, I was not yet into astronomy in graduate school.  A few years later, by chance I acquired a telescope.  A friend of mine in the lab was moving and needed to get rid of some things he wasn't using anymore, and this included an old telescope.  It was an entry level 4.5 inch reflector.  The eyepieces that came with the scope were basically unusable, but after buying a few decent eyepieces, I was amazed at what could be seen even with such a beginner telescope.  At the time, I had no idea you could even see Saturn's rings or detail on Jupiter with small scopes.  After about a year observing with that scope, I bought a more serious telescope.  The Moon looked amazing, and so I started taking photos just by holding my phone up to the eyepiece.  I soon became aware of the incredible results people were obtaining with dedicated astronomy cameras, and so I bought one and got started with more serious imaging of both the Moon and planets.  This reminded me a lot of microscopy, and the astronomy cameras actually look very much like the type we attach to our microscopes....just simple CMOS sensors with an aluminum body that you control with a laptop.  I found that this type of imaging quickly becomes addictive, and so I haven't grown tired of it yet.  In particular, I'm fascinated by the changing views we get of the Moon.  Despite having a reputation among some imagers for being boring and unchanging (and actually hated by many observers who like dark skies), I find the Moon to be an endless supply of enjoyment, and with the combination of phase and libration, we almost never get the same exact view twice.  

 

The Lunar Observing forum on Cloudy Nights doesn't get nearly the same level of traffic as some of the other forums here, but there are many knowledgable observers here, and many interesting posts made, as this topic has surely proven to be!  Thanks again to Klaus for initiating the topic, and to all of the contributors! 


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#14 Lindhard

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Posted 03 August 2019 - 09:05 AM

This is an interesting thread. 

 

Photos of the ray can be seen in section 25 in "Photographic Lunar Atlas for Moon Observes" by Kwok C. Pau

 

http://lunaratlas.bl...s-returned.html

 

I have tried to find the hole/depression in the crater wall where the ray is made.

 

I have attached a close-up version of Tom's photo and photos of the crater wall from LROC.

 

I believe there is a depression where a small crater is placed on the rim. The ray may come from this place. 

Attached Thumbnails

  • tomcloseup.png
  • rim1.jpg
  • rim1a.jpg

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#15 Tom Glenn

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Posted 04 August 2019 - 03:00 AM

Lars, nice analysis, and I think the depression is very close to the mark you have made.  I have analyzed this a bit further, and there is a prominent impact crater in the western wall of Maurolycus, slightly below and to the left of your mark, that I think is the source of the ray.  The name of this crater is Maurolycus T.  Shown below is my image, calibrated into LTVT and then measured with respect to the shadows.  The red lines are drawn in the direction of the Sun.  The elevations given are approximate elevations, calculated by measuring the shadow length.  These types of measurements always have some considerable error associated with them, but in this case values of about 4km are approximately correct for the walls of Maurolycus in this region.  More importantly, the red lines delineate the region in which the depression could occur.  I have also used LTVT simulations of the same region at different times during the development of the ray to verify these coordinates.  

 

Maurolycus_measurement.jpg

 

The depression must exist within a range of selenographic coordinates bounded by the points 11.6E, -41.08S. and 11.28E, -41.51S.  When I marked these points in the LRO Quickmap, it shows that a prominent crater (Maurolycus T) is contained between them that causes a significant depression in the western wall of Maurolycus.  Shown below is a view looking west over Maurolycus from above the eastern wall, and the dots mark the coordinates I mentioned above.  Also shown is a closeup of the depression, as it would be viewed from near the floor of Maurolycus.  You could imagine the Sun sitting in that prominent notch.  

 

notch.jpg

 

notch_closeup.jpg

 

Shown below is the Maurolycus T region, (again produced with the LRO Quickmap tool), but this time looking to the east.  Several craters are labeled in the image.  The depression caused by Maurolycus T in the western wall of Maurolycus is fairly significant, with LRO elevation data indicating a drop of about 1.5km in the saddle point created by sub-crater T.  

 

notch_west.jpg

 

notch_profile.jpg


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#16 Tom Glenn

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Posted 04 August 2019 - 03:24 AM

I ran out of room for uploads in the last post, so had to include these two additional images here.  Because images from Earth have perspective which can add to error in measurements away from the sub-Earth point, I wanted to provide these examples of measurements taken with LTVT using an overhead simulated view of Maurolycus, which confirms that the measurements taken with my images are fairly accurate.  As the ray pattern develops into the narrow beam, the source of the Sun appears to be in the region of Maurolycus T.

 

ltvt1.jpg

 

ltvt2.jpg


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#17 Lindhard

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Posted 04 August 2019 - 08:26 AM

Fine analysis, Tom, it seems that you found the place.

 

From Dave Mitsky's list I can see that the ray should be visible from my obs on September 20. around midnight UT, so I will check if you are right  smile.gif  



#18 John_Moore

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Posted 04 August 2019 - 04:19 PM

It looks like the 'beam' is a combination of Tom's top rim point near Maurolycus T for the top shadow's formation, but for the bottom shadow's formation, it may be due to a high point on the peak terrain at centre of Maurolycus. Below, a topographic texture overlaid on the shadow image for a time just ten minutes before the original 03.34UT time given. The left side of the peak terrain is in light, but that the bottom shadow starts from the high peak point mentioned on the right side of the peak terrain.

 

John Moore

(top shows overhead view, while bottom a low-angle view looking towards the west, click for larger views)

MaurolycusBeam

 

MaurolycusBeam2

 


Edited by Jayem, 04 August 2019 - 05:26 PM.

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#19 Tom Glenn

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Posted 05 August 2019 - 01:46 AM

John, nice figures, and I agree that the "beam" is the result of both Maurolycus T and the central peak of Maurolycus.  Really, the development of the entire ray is the convergence of two independent events.  The initial ray is formed by the depression in the western wall caused by Maurolycus T.  The shadows bounding this ray of light do not initially touch the central peak of Maurolycus.  The central peak does, however, create its own dramatic shadow.  As time goes on, these two events interact to create the beam that we have been discussing.  I made the animation below, which depicts the development of the ray starting at the time of my image, on September 30, 2018 at 11:55UT and proceeding in 30 minute increments until 15:55UT, which corresponds to the approximate stage in development of the beam observed by both Klaus and David.  As the ray develops, part of it is blocked by the central peak, and the shadow bounding the ray to the north starts to "catch up" to the shadow of the central peak.  There is definitely a lot of interesting things going on in this seemingly simple ray.  

 

Maurolycus_ray_development.gif


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#20 Tom Glenn

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Posted 05 August 2019 - 01:58 AM

The other interesting thing is the "seasonal" changes in the beam that occur with changing subsolar latitude.  Shown below are two simulations of the event, taken from the "summer" and "winter" extremes for 2019, in which the subsolar point is at the highest point above and below the lunar equator, respectively.  This corresponds to the April and October events (with the October event yet to occur).  The red lines mark solar azimuth directions from the indicated points.  Although the width of the beam is different in the two "seasons", in both cases the northern shadow boundary traces back to the region just to the north of Maurolycus T, while the vertex of the beam traces back to Maurolycus T itself, and the southern shadow boundary traces back to the central peak of Maurolycus, as John stated above.  The contour lines are 1km intervals, just to make it easier to see the relative boundary of the central peak.  

 

Maurolycus_ray_seasons.jpg


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#21 stickler

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Posted 06 August 2019 - 12:44 PM

I have really enjoyed this discussion and seeing what's possible with modern imaging and lunar analysis tools!

For historical interest, I dug up my original visual notes of the Maurolycus Sunset Ray in September 2000.

I had done a quick sketch at the eyepiece, in an astronomical pocket calendar notebook I was using 19 years ago.

The orientation is upside down because I was using a 7 inch Newtonian, but I left the sketch as-is to make the associated jottings from Sept 19, 2000 easier to read.

Very humble and old-school, but it's still interesting to compare the old visual observation with the great images and high resolution analysis that are now possible a full Saros cycle later!

 

-David Kingsley 

MaurolycusSunsetRay(Sept2000)

 


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#22 stickler

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Posted 07 August 2019 - 01:56 AM

And here's a reoriented version of the old sketch alongside a cropped version of the Maurolycus sunset ray from Klaus's recent image. 

 

MaurolycusRayComparison

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#23 astrolexi

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Posted 08 August 2019 - 01:38 PM

Thank you so much to all for this incredible analysis of this tiny phenomenon!!

David's sketch makes it complete. Thanks a lot!

 

Am I wrong or did really someone say "boring" further up? wink.gif

 

Best wishes

Klaus



#24 aeroman4907

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Posted 22 August 2019 - 06:08 AM

Tom mentioned to me yesterday in a message that I likely caught the Maurolycus Beam while imaging early yesterday.  Tom - you were indeed correct and here is what I captured.

 

Maurolycus-Beam.jpg


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#25 cpsTN

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Posted 12 September 2019 - 05:59 PM

Gosh! What a superb beam that is in the centre of the 114 kms crater Maurolycus!

It's seriously spooky -straight from a science fiction movie. 

 

I am also greatly admiring the barely visible raised rim of the adjoining crater Barocius (82 kms).  

 

Excellent image, Klaus! Thank you

 

Kindest regards, 

 

Aubrey. 

Your post reads like a commercial. smile.gif




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