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December 11, 2019 (PST) Cold Moon

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#1 james7ca

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Posted 12 December 2019 - 02:58 AM

Well, the skies were partly overcast and I didn't have any frames that were completely cloud free, but I was able to image the December full moon within the same hour that it reached its full phase here on the west coast.

 

This is a stack of 16 frames that were taken with a 9.25" Celestron EdgeHD and a Sony NEX-5R camera (ISO 100, 1/250s). It's a two panel mosaic created with Microsoft's free Image Composite Editor (i.e. ICE) with additional processing done in AutoStakkert!, Registax, and Photoshop CC2019.

 

Note how the limbs of the moon are showing practically no shadows, it's a true FULL moon, unlike many shots that capture the moon when it is hours or even a day away from the actual event.

 

The image quality is pretty poor at anything near full scale as I was imaging through fairly heavy high clouds. But, at least I captured the moon quite close to a completely full phase which isn't possible that often from any given place or hemisphere on earth (at least when the moon is high in the sky and so near the winter solstice). You can find more information on these kind of events at the following link here on CN (with future dates for the next five years). 

 

  https://www.cloudyni...1/#entry9812291

 

I think the only regions in the lower 48 states that had much clear weather to try and capture this event were along the eastern coastline and a few points inland over the midwest and southeast. The east coast would have had the best view, since the moon was passing through their meridian just as it reached the full phase.

Attached Thumbnails

  • December 11 2019 (PST) Cold Moon (Small).jpg

Edited by james7ca, 12 December 2019 - 03:01 AM.

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#2 Tom Glenn

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Posted 12 December 2019 - 03:29 AM

Looks good at this scale, James.  You can see a few very small shadows in the vicinity of the North Pole, due to libration as we talked about in your other thread.  But otherwise, you're right...no shadows.  I didn't setup the scope tonight, partly because of time constraints but also the cloudy cover reduced motivation.  I did take a quick snap shot with my DSLR and a 200mm lens, but nothing more.  



#3 happylimpet

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Posted 12 December 2019 - 03:55 AM

Very nice. I also shot the moon last night at around 00UT 12/12/19 (or 12/12/19 in US date format). There was definitely some phase visible then on the east side (not lunar east, our sky east).

 

Have you turned up the colour saturation at all? I cant decide!



#4 james7ca

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Posted 12 December 2019 - 04:39 AM

Well Tom, or anyone else here in California, you'll only have to wait another five years until Dec. 15, 2024 to have a similar opportunity. wink.gif

 

As for the processing, the image quality was pretty bad and the sky around the moon came out fairly bright (because of the clouds) so I needed to really pump the gamma and curves to get any contrast at all. There was also some boost to the color (U.S. "format" for colour) saturation, but I had to back off on that because of the low quality subs.

 

Anyway, it cleared up somewhat at around midnight so I took some more subs. Still had clouds drifting through in many parts of the sky and I had to interrupt my captures several times for them to pass. But I may get a better image although the moon will be over three hours pass full.


Edited by james7ca, 12 December 2019 - 04:40 AM.


#5 Scott Beith

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Posted 12 December 2019 - 12:13 PM

Nicely done.  It is a shame the image quality suffered at full res because that would make one heck of a nice poster!  waytogo.gif



#6 Tom Glenn

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Posted 12 December 2019 - 08:43 PM

Well Tom, or anyone else here in California, you'll only have to wait another five years until Dec. 15, 2024 to have a similar opportunity. wink.gif

 

Fortunately, James, I might not have to wait quite that long!  From your list, the Full Moon of November 30 next year will be slightly higher in the sky in San Diego at the moment of the greatest illumination.  And even sooner than that, the February 9, 2020 Full Moon (two months from now) occurs at 07:34UT, which corresponds to 11:34pm PST on February 8, 2020.  This occurs just about 30 minutes after culmination, and the Moon will be 73 degrees altitude at my house at the time of the Full Moon.  Your other thread, I believe, only included Full Moons from November to January.  The declination of the Moon doesn't start to change rapidly until we approach the equinoxes, so your search parameters can be relaxed somewhat if the goal is to find Full Moons that are reasonably high in the sky.  Shown below is the JPL ephemeris for the February Full Moon, with the highlighted time segment being closest to the moment of the Full Moon.  Note that the libration is to the South, and is stronger than it was (in the opposite direction) to your image above.  This makes the illumination "only" 99.909%, and there will be some hints of shadows near the southern limb.  The apparent size of the Moon will be about 100 arc seconds larger than it was yesterday.  Of course, all of this is weather permitting, which in February is questionable.  

 

JPL_ephemeris.jpg



#7 james7ca

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Posted 12 December 2019 - 10:26 PM

Yes, but next year's November 30 full moon will be a penumbral lunar eclipse which will be an interesting imaging opportunity but you won't have a fully bright moon like last night or the event in 2024. That's the reason I skipped next November's moon, it will be "full" and pretty high in the sky but dimmed by the earth's shadow. And speaking of eclipses the next "good" one for us on the west coast will be on March 13–14, 2025 when the totally eclipsed moon will be about 56 degrees above the horizon and less than one hour from transit.

 

Also, we'll be having lunar eclipses in the month of November for three years running starting next year (Nov. 30, 2020, Nov. 19, 2021, and Nov. 8, 2022) and I updated my list a few days ago to show these lunar eclipses. The Nov. 19, 2021 eclipse will be pretty good for the west coast, but it won't be a total eclipse (close at 97%).

 

That said, you are certainly correct that you can search for other opportunities that would fall outside of the months of November through January and your February 9 event looks like a good one. You are also correct that the weather can either break or make these opportunities and you can certainly get a good full moon shot at any time of the year if both the weather and the seeing conditions are favorable. Because of the latter, last night wasn't nearly as optimal as it could have been and in addition to the clouds I think the seeing was below average (I tried to check the collimation on my EdgeHD but the seeing wasn't good enough to even try an adjustment).

 

However, I was able to get some shots at around midnight when the moon was nearly 74 degrees above the horizon, although a few hours past the 100% full phase.


Edited by james7ca, 13 December 2019 - 12:37 AM.


#8 james7ca

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Posted 12 December 2019 - 11:22 PM

Here is an image that I captured at around 12:40AM on the morning of December 12. This was just over three hours past the 100% full phase but the moon was even higher in the sky (about 74 degrees) and there were far fewer clouds. I tried to time my captures to avoid the clouds but I think a few frames had some wisps of thin cloudiness. However, my earlier capture (post #1) was done through a definite and persistent layer of high clouds.

 

This later capture looks okay at larger sizes and would probably make a decent print. However, you can definitely see a little bit of shadowing on the eastern limb of the moon (look along the right side). I allowed the best 24 of 32 frames at ISO100 and 1/320s using a Sony NEX-5R camera and a 9.25" EdgeHD. Processing in AutoStakkert!, Registax, and Photoshop CC2019 and as before I used Microsoft's ICE program to combine two fields into the final mosaic (before the final adjustments in Photoshop).

 

It was hard to get this image to compress down to under the 500KB limits on CN so the quality shown here is certainly below what I see on my display.

Attached Thumbnails

  • Dec 12 2019 Cold Moon (Small).jpg

Edited by james7ca, 13 December 2019 - 01:19 AM.

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#9 james7ca

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Posted 12 December 2019 - 11:57 PM

And for those who may like COLOR, here is a high saturation version of the image.

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  • Dec 12 2019 Cold Moon Color Saturated (Small).jpg

Edited by james7ca, 13 December 2019 - 01:53 AM.

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#10 happylimpet

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Posted 13 December 2019 - 05:42 AM

Yes, but next year's November 30 full moon will be a penumbral lunar eclipse which will be an interesting imaging opportunity but you won't have a fully bright moon like last night or the event in 2024. That's the reason I skipped next November's moon, it will be "full" and pretty high in the sky but dimmed by the earth's shadow. And speaking of eclipses the next "good" one for us on the west coast will be on March 13–14, 2025 when the totally eclipsed moon will be about 56 degrees above the horizon and less than one hour from transit.

Well, the fullest moon we can image will always be when its just outside the penumbra, regardless of whether this is a 'classic' full moon riding above/below the penumbra or the moon shortly after eclipse, when it is just as (if not more) full but the 'phase' on on the east/west limb rather than the north/south limb.


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#11 james7ca

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Posted 13 December 2019 - 07:00 AM

Well, the fullest moon we can image will always be when its just outside the penumbra, regardless of whether this is a 'classic' full moon riding above/below the penumbra or the moon shortly after eclipse, when it is just as (if not more) full but the 'phase' on on the east/west limb rather than the north/south limb.

That's a valid observation.

 

I'm not sure how much the eclipse next November will affect the appearance of the moon, at maximum it will be over 80% covered by the penumbra so it may take on a somewhat dulled and dimmer look (I've called that a soft "pearl like" appearance during other eclipses ). But, I guess the challenge will be to see if it looks any different than a normal moon.

 

Here is a link to a full moon that I took in 2016 just before it entered into eclipse:

 

  https://www.cloudyni...dpost&p=7125728


Edited by james7ca, 13 December 2019 - 08:42 AM.

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#12 Tom Glenn

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Posted 13 December 2019 - 06:31 PM

That's a valid observation.

 

I'm not sure how much the eclipse next November will affect the appearance of the moon, at maximum it will be over 80% covered by the penumbra so it may take on a somewhat dulled and dimmer look (I've called that a soft "pearl like" appearance during other eclipses ). But, I guess the challenge will be to see if it looks any different than a normal moon.

 

Here is a link to a full moon that I took in 2016 just before it entered into eclipse:

 

  https://www.cloudyni...dpost&p=7125728

I think the penumbral eclipse will make the imaging more interesting.  These sorts of eclipses are generally not readily detectable by naked eye observation, but it will probably result in a few stops difference of exposure on the camera.  The penumbral eclipse begins at 7:32UT on November 30, 2020, and ends at 11:53UT.  The Full Moon occurs at 9:30UT.  Interestingly, if you image the Moon either immediately before or after the eclipse (so there is no dimming due to Earth's shadow), the illuminated fraction will be 99.984% in both cases (geocentric, more on this below).  Despite being about two hours away from Full, this percentage of illumination is higher (barely) than the Full Moon from yesterday (which was 99.979%).  

 

Also interesting is that when you look at ephemeris charts, you quickly discover things that might not initially be intuitive.  One is that the STO (Sun-Target-Observer) angle is almost never at its minimum value at the exact moment of the Full Moon.  The Full Moon is defined as the moment when the ecliptic longitudes of the Sun and Moon differ by 180 degrees (geocentrically measured), but the sub-solar point and sub-Earth points on the lunar surface are almost never coincident since the Moon is not orbiting in the same plane.  So, depending on the motion of the Moon relative to the ecliptic at the time, the geocentric STO angle is at its minimum either before or after the actual moment of the Full Moon (looks like this can be at least 30 minutes or so, on either side).  Additionally, if you enter your geographic location into the JPL Horizons ephemeris calculator, you will also find that your position on Earth changes the STO angle and apparent illuminated fraction, due to parallax, albeit by very small amounts.  Interestingly, this means that for San Diego, the November 30, 2020 Full Moon will reach a maximum illuminated fraction of 99.990% at 10:22UT, which is almost an hour past the actual moment of the Full Moon.  In this case it's not very helpful for imaging, because the Moon is already well past the meridian, but I find it interesting that the timing of maximum "apparent fullness" is quite dependent upon location, and does not necessarily occur at the astronomically defined moment of the "Full Moon".  As the terminator sweeps across the Moon, the rotation of the Earth changes our view of the limb, which in the above case causes our locally perceived "full" Moon to occur later.  The apparent 99.990% illuminated fraction continues in San Diego for over an hour, until 11:31UT, a full two hours past the actual moment of the Full Moon.  


Edited by Tom Glenn, 13 December 2019 - 06:37 PM.

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#13 james7ca

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Posted 13 December 2019 - 10:44 PM

This is all interesting and potentially useful information and I may redo my list of full moons that happen near to the winter solstice. My criteria for that list included both the time of the full moon and how close that fell to when the moon reached my local meridian. Reason being that the moon will be highest in the sky when it reaches the meridian, thus improving my chances of having better seeing conditions during the event.

 

The full moon on November 30, 2020 is kind of a special case since it will also be a penumbral eclipse. The "full" phase of the moon will happen during the eclipse and by the traditional definition of a full moon the time of that event will be approximately 9:30UTC (about 1:30AM PST). However, the moon will be crossing my local meridian at 7:33UTC or (11:33PM PST on November 29). Interestingly enough, the eclipse begins at 7:32UTC which will be the last moment that you could image the moon before it enters the earth's penumbra. So, putting all of this together my best opportunity to capture the nearly full moon will be just prior to the start of the eclipse and just one or two minutes before the time that the moon reaches my local meridian (basically, the beginning of the eclipse happens at the same time as the moon reaches my meridian).

 

So, using JPL/NASA's Horizon web interface and selecting a time of 7:30UTC we have the following data for San Diego, Ca:

 

Date__(UT)__HR:MN     R.A._(ICRF/J2000.0)_DEC Azi_(a-appr)_Elev  APmag  S-brt   Illu% Def_illu Ang-diam  T-O-M/Illu%

2020-Nov-30 07:30  m  04 22 58.67 +20 13 48.5 175.3143  77.5263 -12.64   3.39  99.980   0.3597 1811.383 0.0000/100.0

 

So, the apparent elevation of the moon will be 77.5 degrees and the illumination will be 99.98%. Peak illumination (without the eclipse) would happen at 11:00UTC (about 3AM PST) at 99.99% but that will also be during eclipse and the apparent elevation of the moon will only be 43.8 degrees (i.e. much lower in the sky). The penumbra eclipse ends at 11:53UTC (3:53AM PST).

 

Using the data from this past full moon (and from San Diego, it was a much better event further east where in Miami the full moon had an elevation of about 86 degrees) we have the following:

 

At the full moon, 9:14PM PST:

 

Date__(UT)__HR:MN     R.A._(ICRF/J2000.0)_DEC Azi_(a-appr)_Elev  APmag  S-brt   Illu% Def_illu Ang-diam  T-O-M/Illu%

2019-Dec-12 05:14  m  05 17 25.28 +21 06 50.3  99.5117  54.6733 -12.74   3.39  99.969   0.5844 1897.917 0.0000/100.0

 

Thus, the apparent elevation of the moon was 54.7 degrees with an illumination of 99.969%.

 

And, when the moon crossed my local meridian at 11:49PM PST:

Date__(UT)__HR:MN     R.A._(ICRF/J2000.0)_DEC Azi_(a-appr)_Elev  APmag  S-brt   Illu% Def_illu Ang-diam  T-O-M/Illu%

2019-Dec-12 07:49  t  05 21 23.83 +21 24 18.0 180.8072  78.7071 -12.74   3.40  99.964   0.6832 1905.252 0.0000/100.0

 

Apparent elevation of the moon was 78.7 degrees with an illumination of 99.964%.

 

Bottom line, the "full" moon on November 30, 2020 (if imaged before the start of the eclipse) will be roughly the same as the event we had this past Wednesday/Thursday. Near transit time (meridian crossing) the key data points are (I've added angular diameter since that will determine the size of the moon):

 

Date                  Percent Illuminated     Apparent Elevation     Angular Diameter

Dec 12 2019      99.964%                           78.7 degrees                 1905"

Nov 30 2020      99.980%                           77.5 degrees                 1811"

 

Probably the only significant difference is in the size of the moon, this December's moon was about 5% larger than next November's.

 

I guess what has been shown here (by Tom, happylimpet, and me) is that determining the best full-moon events can be a little complicated.


Edited by james7ca, 13 December 2019 - 10:51 PM.


#14 Tom Glenn

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Posted 14 December 2019 - 01:42 AM

 

I guess what has been shown here (by Tom, happylimpet, and me) is that determining the best full-moon events can be a little complicated.

Agreed on this point.  If I were compiling a list, I would probably take a look at all the Full Moons that have positive declination, which would put them at ~58 degrees and higher altitude above the horizon in San Diego at meridian crossing.  Although my best lunar imaging sessions have all occurred at altitudes of 65 degrees and above, setting declination to 0 and greater is probably a good conservative parameter.  I've been pleasantly surprised by Moons in the 50's (and conversely very disappointed by Moons above 70 degrees on occasion), all because of the seeing.  That being said, it does make me envious of those living near the equator, in which the Moon (and planets) just meander back and forth across zenith, never falling too far below 70 degrees altitude at culmination.  

 

If we assume that weather and seeing were not a factor, then I would probably put the most weight behind the apparent size of the Moon.  The difference in size between the Moon at apogee and perigee is about 14%, and this is actually quite significant when imaging.  When using your C9.25 Edge, it is analogous to the difference between imaging at f/10 and f/11.4 (if you were using your ASI183 this would essentially make it closer to "perfect", although any camera would benefit from the increased apparent size), but without actually incurring any penalty in SNR since you would still be at f/10.  


Edited by Tom Glenn, 14 December 2019 - 01:47 AM.



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