Lunar eclipse!

The morning of Tuesday, April 15 saw the first of four lunar eclipses slated to occur over the next two years. That's celestial mechanics for you--like a Venusian transit of the sun, these things come in groupings. Unlike Venus passing in front of the sun (which happens at century-long intervals), lunar eclipses are comparatively common. But not that common. The last lunar eclipse visible from North America, in 2010, didn't turn out so well for me. Because of the chance of clouds at any time, I was determined to take advantage of the opportunity this time around.

Several things are different now than they were back in 2010. For one, I have a different mirror in my telescope, which I'm still sad about. The second is that I've figured out why there was so much diffusion in my 2010 photographs--the plossl eyepieces I use for visual observing introduce field curvature, which causes the edges of the image to be out of focus. If I'm ever to get serious about eyepiece projection astrophotography, I'll need to invest in flat-field orthoscopic eyepieces. I've also got a better camera--the Canon 7D--and have learned I can use a telextender to double the telescope's focal length, thus making the moon fill the frame of my camera. Finally, I've got a rock-steady Orion Atlas equatorial mount for my telescope, a significant upgrade from the 1970s era pier GEM mount that came with the scope.

Unfortunately, I wasn't feeling all that well, and wasn't up to doing much preparation. And I'm still not entirely familiar with the Atlas mount, so wasn't able to get it to track the moon very accurately (although the electronic controls worked very nicely and allowed me to position the image precisely). I moved the mirror up in the tube so I could shoot at prime focus with the camera. Ideally, when I did this, I should've collimated the scope to make sure the mirrors were in good alignment to ensure the best possible image. But I was tired and sickish so I didn't.

As for the weather, this time around I was not plagued by clouds. The sky was crystal clear, in fact, and it got pretty darn cold for Texas in April--down to the lower 40s. Brr. Which should've meant great views, but it didn't. There was a good bit of wind on the ground, and a lot of turbulence up high in the atmosphere, making the moon's edges waver and forcing me to adjust focus regularly simply because the "boiling" effect of the atmosphere made it impossible to be certain I ever nailed focus. None of my photos turned out as sharp as I'd have liked because of that, but overall it wasn't a bad effort. The 6" Meade 645 f/5 Newtonian has a focal length of 762mm, and for most of the night I used a Vivitar 2x telextender, which essentially turned the scope into a 1524mm f/10.6 lens. I had to remove the telextender during total eclipse, though, because the moon was too dim to shoot without those two extra stops of light--and even then I cranked the ISO up to 3200 (which introduced significant noise to the image). The good news is that I'm progressing with my competence in astrophotography. The bad news is that I clearly have a long way to go. I combined 30-something images into the animated gif above. You can see a progression of the original still images below. Hopefully, by the time the next lunar eclipse comes around, I'll have mastered the Atlas' tracking and be able to shoot totality using much lower ISO and longer shutter speeds.

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