Lunar Limb profile extraction from Solar Eclipse imagery

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AndrevdHoeven
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Lunar Limb profile extraction from Solar Eclipse imagery

Post by AndrevdHoeven » Mon Sep 25, 2017 8:13 pm

A while ago I saw a post from Pete Lawrence from BBC Sky at Night on Facebook in which he showed that you can see the lunar limb profile in the images from the Baily beads taken during the solar eclipse. When I started making an beads sequence I remembered this post and thought it was worthwhile to see if I could do something like that also. It showed that I had about 15 bead images during C2 and C3 and so I started adding them to my image and I was heavily surprised. What I basically did is putting the chromosphere/bead imagery on a very tight spacing, as if it is basically a sequence of the sun disappearing behind the moon and coming back.

Using Solar Eclipse Maestro I then generated a lunar limb profile (80x exaggerated) to compare with my imagery. This is shown as the white line on the inside of the beads. What surprised me was that the limb was so clearly visible and coincided so well with the predicted profile, but even more that also in the part outside the beads you can still see limb features in the solar chromosphere clearly.

In the image I tried to link some of the features to the chromosphere banding that is visible. This is a nice example how you can even do some 'science' using your own eclipse data.

The images were taken with a Nikon D810a equipped with a Nikon 300mm f/4 lens.

Image
Lunar Limb profile from Solar Eclipse imagery by Andre van der Hoeven, on Flickr
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bart1805
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Re: Lunar Limb profile extraction from Solar Eclipse imagery

Post by bart1805 » Mon Sep 25, 2017 9:47 pm

Wauw, dat is echt briljant!
What an amazing job, really impressive!!

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Montana
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Re: Lunar Limb profile extraction from Solar Eclipse imagery

Post by Montana » Tue Sep 26, 2017 9:31 am

Amazing work Andre, it matches very well indeed, superb science :) so now you can name the mountains that caused the beads?
:bow :hamster:
Alexandra

AndrevdHoeven
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Re: Lunar Limb profile extraction from Solar Eclipse imagery

Post by AndrevdHoeven » Tue Sep 26, 2017 10:00 am

That is definitely possible. I already was looking at that :)
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Re: Lunar Limb profile extraction from Solar Eclipse imagery

Post by marktownley » Tue Sep 26, 2017 6:29 pm

Pretty darn funky! I agree!
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AndrevdHoeven
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Re: Lunar Limb profile extraction from Solar Eclipse imagery

Post by AndrevdHoeven » Tue Sep 26, 2017 8:11 pm

Montana wrote:
Tue Sep 26, 2017 9:31 am
Amazing work Andre, it matches very well indeed, superb science :) so now you can name the mountains that caused the beads?
:bow :hamster:
Alexandra
I even got a request from the maker of the software package to use the images to do some scientific measurements :) Always like something like that...
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Carbon60
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Re: Lunar Limb profile extraction from Solar Eclipse imagery

Post by Carbon60 » Wed Sep 27, 2017 5:36 am

I love this kind of stuff. Excellent work.

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AndrevdHoeven
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Re: Lunar Limb profile extraction from Solar Eclipse imagery

Post by AndrevdHoeven » Thu Sep 28, 2017 11:44 am

This image is an further work on a previous image that I released last week. After finding that it was possible to bring out details of the lunar limb using the imagery made during the total eclipse I started looking a bit further into the topic. It showed that there is very nice software from the International Occultation Timing Association, called Occult, that contains a very accurate height model of the moon that can be used to for timing of occultations of stars by the moon. This same software can also generate lunar limb graphs for solar eclipses.

I decided to put the software to the test and see how well it would coincide with the images that I made. So I used the GPS coordinates that I grabbed during the eclipse and started to look at the generated graphs for the exact times of the 2nd and 3rd contacts. I was astonished to see the accuracy of the software. The graphs exactly coincide with the Bailey beads that I observed and imaged. In this way you can retrieve the times that the images were taken to about 1/10 of a second accurate.

In this image I have tried to put it all together. On the sides you can see images taken around 2nd and 3rd contact together with the height model and locations in yellow where the sunlight passed through the valleys between the craters. In the central image you can see a 'stack' of all my bead images that leads to an impression of the lunar surface structures on the limb during the eclipse from our location, Teton Village, WY.

All images were taken with a Nikon D810a with a 300mm Nikon lens.

Image

Lunar features visible during totality... by Andre van der Hoeven, on Flickr
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Re: Lunar Limb profile extraction from Solar Eclipse imagery

Post by Montana » Thu Sep 28, 2017 11:58 am

Your images get better and better!!! :hamster:

Alexandra

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