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Celestron 3 star alignment using 2 stars!
Morning guys,
Last night I had to do a small experiment with my scope that turned out well. I was at a school for a presentation to the public with the ASV but unfortunately when I was ready to set up my GoTo and had no stars in the east to go to! I could identify Procyon and that was it. The whole southern sky was covered in cloud and too much glow in the east to see much. For anyone who is not aware of the options for the Celestron Advanced Series (about 2 years old) you need to do a three star alignment. Two stars in the East and 1 in the West, starting in the East. The other 7 or 8 scopes were already picking out objects from amoungst the cloud breaks while I was still waiting for "something" to be visible. People were swanning around my scope eager to see what it can do, especially the kids who never knew you can get a scope with a computer in it!
After more than half an hour I decided to try something I have never tried before. I chose the first alignment star, Procyon, and centered it. The scope suggested another target for the second one, so I scrolled back to Procyon and selected it. I was expecting the scope to say something like "sorry mate, but you already did that one before!" It slewed a little and pointed to the same place as before, about a degree or so from Procyon. So I centered it and chose the next one. It suggested Sirius, which was one of the only stars currently visible, so I selected it.
Alignment success! For a test of the accuracy I chose M42 (which was actually one of my targets for the night anyway). It swung into action. When it stopped, M42 was at about "2 o'clock" in the eyepiece, about two thirds of the way from the centre, and that was with an 8mm Stratus giving a magnification of 125x! I must admit that is pretty impressive.
Polar alignment consisted of using a compass only and pointing it in a reasonable aproximation to true south. I did not expect it to be too good as both alignment stars were quite close, and it only really had two stars. So, if you are running short of stars, you may like to try this. I'd be interested to know if anyone else has tried "cheating" when aligning.
BTW the kids, and especially the dads, thought the laser was pretty smooth! Even the teachers were surprised with the computer.
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