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Monday, August 06, 2018


Animations of the July 28 Lunar eclipse (2018)

Entire sequence of the eclipse stacked and aligned in GIMP, starting every 5 minutes until totality and then every 10 minutes until the Moon finally disappeared behind the roof tops (4:06 am.-6:23 am) Sadly the later stages are made rubbish by whatever compression  GIMP uses, but you can see the beginning of the glow as maximum eclipse passes (totality ended at 6:44 am; click to embiggen). Inital sequence of the eclipse up until the start of totality stacked and aligned in ImageJ, starting every 5 minutes until totality. I didn't do the full sequence as aligning moon images in ImageJ is a right pain, and they tend to get out of sequence. but the quality of the fully eclipsed images is much higher.

Here, as promised, are my animations of the total lunar eclipse of July 28. Because the motor drive on the telescope decided to stop working, I had to manually drive the scope, and the images were not aligned, so I had to align the images by hand. This is a pain in both GIMP and ImageJ (even though there are tools in both to do it they each have their own limitations.

But in the end it work out okay, mostly. not too happy with the way GIMP made the eclipsed images low res, but it does give you a feel for what it was like.

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Hi Ian

Thanks for Astroblog, it's a great resource.

The issues you describe are almost certainly artifacts of the GIF file format rather than the GIMP. The GIF file format is an indexed format which only allows 256 colours. This is fine for just the white moon or just the red moon because GIMP will optimise the palette it uses, but the white moon turning red is probably too many colours to look good as a GIF. You'd probably get better results if you use the Gimp Animation Package (GAP) plugins for gimp, which will allow you to render your animations as AVI or MP4. These files are also often smaller than GIF for large or long animations. On ubuntu (and probably debian too) you can install this with 'sudo apt-get install gimp-gap'. There are tutorials online but if you need help i can be reached at antisol at antisol dot org. Cheers.

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