Observation Log 3/28/06: Got the scope out to try the Dew Shield. Saw some planets & moons, found a surprise!

Tonight was the clearest, best seeing night in a while. So I got out the Celestron NexStar 8i telescope to try out my new Dew Shield. Not having any specific goals for the night, I played a bit, and found the beautiful NGC 1502 cluster

First off, even though this was the best night in a while, I was really disappointed how much sky glow I saw. After my eyes adjusted (I was out for 90 minutes or so) my surroundings looked like the Moon was illuminating them. Even the view from the eyepiece was alarmingly bright in the background. I guess it’s time to look for a Light Pollution Filter, probably one that fits on the back of the scope.

The dew shield did its job quite well. My corrector plate (the frontmost glass on a Schmidt-Cassegrain scope) usually gets fogged up after a half hour on chilly, damp nights like tonight, but it performed like a champ. After months of non-use, I found my scope needed collimation, and when I defocussed to get a look at the Airy Disk, I saw that the shield was obscuring some of the incoming light. I had put the shield on a bit crooked. I think it will take a bit of practice to get it right the first time.

So, since my main target, M1, had already set for the evening, I took a look at Saturn and its moons (and logged a few new ones) and Jupiter and its moons. I was able to see the Cassini Division in Saturn’s rings during moments of clear seeing, as well as some several bands on Jupiter. The focus was not good, and sure enough, I found the collimation was out a bit. I found Arcturus, and fixed it up.

Now the fun began in earnest. I’ve written about my search for Kemble’s Cascade in the past, always using binoculars. Though it was low in the sky glow to the north, I took a look. I had read somewhere (sorry I can’t attribute it) that the Cascade was “like a waterfall, emptying into a pool of diamonds.” I had no idea what that meant until tonight. With my scope at 120X with a Nagler 17mm eyepiece, the Cascade was 3 to 4 fields of view wide. Even so, panning along its length it was striking. I reached its northern end, and just looked around. I found a field with a cluster of beautiful stars, mostly arranged in pairs, sharp, bright, and striking. I made a mental note of the arrangement and looked it up when I got back inside. Of course, it was NGC 1502, the “pool of diamonds” I’d read about but never seen.

I saw one very odd thing I could not explain. At one point, while collimating on Arcturus, I had the scope so defocussed that the Airy Disk almost filled the field of view. Then, a dark, defocussed object entered the disk from the left, crossing the disk with perfectly constant speed and straightness of path. While it was there, I moved my eye around, trying to rule out some debris on or in my eye. I took off my glasses. My second thought was an insect on the corrector plate, but I’ve never seen one walk so straight and evenly. I can only imagine that I was seeing the transit of a geosynchronous satellite, probably a decomissioned one since Arcuturus is a bit over 19 degress north of the Celestial Equator. I don’t know who to ask about this, since it is so improbable and practically unreproducible, not to mention the complicating factor of the extreme out-of-focus state required to see such a thing.

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