Lunar eclipse animations (Shallow Thoughts)

Lunar eclipse animations

The lunar eclipse on Sunday was gorgeous. The moon rose already in eclipse, and was high in the sky by the time totality turned the moon a nice satisfying deep red.

I took my usual slipshod approach to astrophotography. I had my 90mm f/5.6 Maksutov lens set up on the patio with the camera attached, and I made a shot whenever it seemed like things had changed significantly, adjusting the exposure if the review image looked like it might be under- or overexposed, occasionally attempting to refocus. The rest of the time I spent socializing with friends, trading views through other telescopes and binoculars, and enjoying an apple tart a la mode.

So the images I ended up with aren't all they could be -- not as sharply focused as I'd like (I never have figured out a good way of focusing the Rebel on astronomy images) and rather grainy.

Still, I took enough images to be able to put together a couple of animations: one of the lovely moonrise over the mountains, and one of the sequence of the eclipse through totality.

Since the 90mm Mak was on a fixed tripod, the moon drifted through the field and I had to adjust it periodically as it drifted out. So the main trick to making animations was aligning all the moon images. I haven't found an automated way of doing that, alas, but I did come up with some useful GIMP techniques, which I'm in the process of writing up as a tutorial.

Once I got the images all aligned as layers in a GIMP image, I saved them as an animated GIF -- and immediately discovered that the color error you get when converting to an indexed GIF image loses all the beauty of those red colors. Ick!

So instead, I wrote a little Javascript animation function that loads images one by one at fixed intervals. That worked a lot better than the GIF animation, plus it lets me add a Start/Stop button.

You can view the animations (or the source for the javascript animation function) here: Lunar eclipse animations