2 Hours of Ceres
I read in Astronomy magazine that Ceres was close to us, an easy target. I think they said it was magnitude 7. But part of the challenge of observing Ceres is that it looks just like any other star. So you must observe it multiple times, taking careful notes, sketches, or photographs each time to see its motion relative to the background stars. I decide to photograph it. If your browser can show an animated GIF, you should see 2 hours of Ceres:
What you hopefully are seeing are 3 exposures of Ceres in sequence. Each of those exposures was taken an hour apart between 9pm and 11:07pm March 25, 2009.
Ceres is an asteroid, or more properly, a dwarf planet, that was discovered January 1, 1801 by Giuseppe Piazzi. It is the smallest identified dwarf planet less than 1,000 km in diameter.
The seeing is as good for Ceres right now, best in about the next 1,000 years or so, so I knew I didn’t want to miss it! Ok, I’m being a little silly there, I’m sure that it will be almost as visible many more times, so don’t worry too much.
To get the photo I carefully Polar aligned the Celestron ASGT mount and then as carefully aligned the mount to the star so the GoTo would be dead on. I used 2 alignment stars and 4 calibration stars, and 2 of the calibration stars were near Ceres. I used a fairly high power eyepiece for the alignment.
I then entered the Declination and Right Acension into the hand controller and slew to Ceres. Was it there? I wouldn’t know for a few hours. I took 15 shots of 30 seconds each every half hour from 9:00pm until 11:00pm EDT. (The animation only uses the 1st, 3rd and 5th shots just to make the processing a bit easier on me.)
(I did take some test shots first to make sure the exposure was correct and that the stars weren’t trailing at all.)
I then sat and waited out the exposure, setting a timer to ding every 30 minutes so I would be outside to trigger the camera’s programable timer.
When I was done, (and the last shots were close, I calculated that I was about 5 minutes away from needing a meridian flip!) I downloaded the images. I knew I would process them a few days later but I hastily loaded the first and the last ones into Photoshop, just to do a quick alignment to see if I had caught any movement, had I caught Ceres.
I dropped the images into Layers and set the opacity of the top layer to 50% so I could see both of them. Then I zoomed way in so I colud see the pixels. I clicked away at the arrow keys to nudge the doubled stars to merge.
Drat, I had a problem. I megred the bright star but the rest were still double.
Oh! That’s not a problem, that was Ceres that I merged. It had moved, I had captured it! It might sound dumb but it was pretty exciting to me then.
Just in case you were not able to see the animation above, here are the three frames merged:
Notice the smear in the middle, that’s all three images of Ceres. Here’s the full crop zoom:
Please excuse the Purple Haze around the stars. That is a result of my achromatic refractor and my inability to process stars well.
I’m glad I did it, I still miss the visual observing though. When I set up the scope I couldn’t resist a peak at Saturn. Four moons! That was confirmed by the Saturn Assistant in Astromist. That was a first for me, I had only ever seen 2 before in my equipment. The dimmer two kept popping in and out. And when I took the camera off and was about to call it a night, I considered looking at Saturn again. But I was just too cold and the refractor was pointing almost straight up. I’d have to kneel to see it.
So no more Saturn but yes, I had grabbed Ceres!