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Old 19-09-2009, 10:24 PM
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mithrandir (Andrew)
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Join Date: Jan 2009
Location: Glenhaven
Posts: 4,161
Tom,

I've had my C8 almost a year. I'm still getting the hang of getting it aligned within half an hour. Longer if I want to practice imaging. With patience I can get the errors down to under a second.

Quote:
2. The minimum latitude I seem to be able to dial up on the scope is approx 26 degrees, despite my location being 23 degrees South, which is making the slew slightly out of kilter with the true track of the night sky.
Make sure the peg for the mount is over a tripod leg. Mine wasn't. The builtin level is almost certainly wrong. Use a known good spirit level.

You can set the tripod so the top plate is not quite level by making the south-pointing leg shorter. That should give you 3 degrees without too much trouble. As the mount doesn't rotate on the tripod it shouldn't matter. It might complicate polar aligning a bit (see later) because the software expects it to be level but should not make it impossible.

Quote:
3. Using a 2-star align, I still note that a tour of the night sky - particularly double stars which should be easy to identify - does not align at all (nothing in the finder scope or in the vicinity after doing a scan of the reason around there).
Two part answer.

First the finder. It is simplest to get the finder and the main scope aligned during the day. With the mount turned off, centre the image on the C8 at something fairly distant - a distinctive object on the horizon is good. Use the finder thumbscrews to point at the same object. Make the screws firm. They don't have to be tight - that comes later. That will get you in the ballpark. After dark point the scope so that any easy to see object is on the cross in the finder. Move the scope a little with the motor. Rotate the finder tube so the object is back on one of the crosshairs (not the central cross - just one of the lines). Check the object is centred in the C8. Repeat a couple of times until you are happy.

Second the mount. Have you got the latest firmware? The one that has "Polar Alignment" under the "Align" button menu. That lets you adjust the polar alignment on any object. (The older firmware only works in the Northern Hemisphere.) If not you need a suitable serial cable for the hand controller to upgrade both the mount and hand control firmware. You can get the Celestron one, but there is a diagram you can use to make your own. I used a telephone handset cable with a correctly pinned RJ12 to DB9 plug, plus a DB9 to USB cable.

Quote:
4. I had a little more success with a solar-system align using Jupiter, but still didn't align with other objects in the sky. Granted at this time of day a lot of the stars in the region are unfamiliar to me (Alpha Centuri and a few of the more recognisable night sky objects have now disappeared behind my neighbours roof some hours ago)
Get yourself a copy of Stellarium. Configure your location. You can ask it to find objects (F3) and it will rotate the sky to show them to you.

If you have the cable mentioned above, also get the ASCOM driver software and StellariumScope. Then you can see where the scope is pointed, and point the scope at objects in Stellarium. They won't be perfectly aligned until you get the polar align right, but it will get you reasonably close.

You might get some answers from nearer Blackwater. There are a few IIS members in the deep north.

Good hunting.
Andrew
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