Thursday, March 9, 2017

Aldebaran and the Moon

I realize this post is a little late regarding the occultation of Aldebaran, but in my defense, I have no excuse.

I had miscalculated the time of disappearance March 4, but did decide to go out and see how long before the Moon would cover the star.  I took my binoculars with me and raised them to the Moon only to find Aldebaran moments away from disappearing.  I watched the occultation and went back inside and prepared my camera to photograph the reappearance.

I boosted the ISO on my Canon EOS 60D to 6400, selected Aperture Priority, put on the Canon EF 100-400mm f/4.5-5.6L IS II USM lens and opened it up to f/5.6 at 400mm. Several minutes before the predicted reappearance, I went outside and to begin taking photos (handheld) every 30 seconds or so.

Outside I was greeted with high clouds which varied from thin to thick, but moving fast over the Moon.  I was a little disappointed, but started photographing the Moon, hoping to get something.  When it was a good 15 minutes after the predicted appearance of Aldebaran, I called it a night (it was about 20 degrees at the time) and loaded the images on my computer.  After a quick "look-see" of the RAW images, I didn't see anything and worst of all, the high clouds were blowing out a lot of detail.

The next morning I began looking at the images a little closer and attempted to fix the high cloud glare.  I found an adjustment in exposure, combined with a gamma tweak did a decent job of lessening the glare of the clouds. I applied the changes to all the images and began looking through them.  About midway I noticed something in one of the images which looked like Aldebaran peeking out from the side of the Moon.  The next image proved it as it showed Aldebaran a couple of diameters from the lunar limb.

The image below shows the progression of Aldebaran from hidden to fully exposed.  Images which followed the third photo here were too badly blown out due to thicker high clouds.

In the montage, the first image, Aldebaran is still behind the moon.  In the second image, taken at 20:06:52, a small portion of Aldebaran is visible emerging from behind the moon just above the 3 o'clock position.  In the third image, taken approximately one minute later, Aldebaran is fully visible and away from the Lunar limb.  

I live in central Oregon, however a friend of mine who lives south of Chicago also viewed the occultation.  He sent me this information after viewing my montage.

"Your pictures showed exactly what I saw, Aldebaran to the center right of the "round" North latitude lunar sea Mare Serenitatus. The star had the same look I saw. No color, like it was washed out by the Moon's glare. Your picture is exactly what I remember."

He added the only difference was he could see Earthshine from the north Pacific Ocean.

Until the next clear sky moment, keep looking up!

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