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Old 18-09-2017, 05:14 PM
jimmyh1555 (James)
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long imaging times

Seeing as I am right on the starting line of the learning curve, I can't figure out how you folks can take images of several hours duration over several days Do you have to have a fixed pier or something so that you can leave the telescope fixed up all the time? If you have to take all your gear inside every night, then drag it out again next day, how can you get spot-on alignment?? Then the stars will be in different places in the sky, so do you have to use special aligning software or something? If I tried to get my scope spot-on after a couuple of days, I can bet that the scope will be pointing in completely the other direction, clouds will be blocking the scene, the tripod legs will have sagged, the battery will be flat and the time will be all wrong MUST be something I've missed!
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Old 18-09-2017, 05:34 PM
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that_guy (Tony)
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In terms of your framing, DSS (and other stacking programs) automatically aligns most images. You would need to crop out the difference but it works.
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Old 18-09-2017, 05:59 PM
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doppler (Rick)
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A permanent pier does make it easy for sure, but if you mark the focuser or camera adapter so the camera is in the same spot (or close to) each time you set up then the stacking program will line it all up easily. More advanced users use software called "plate solving" which will analyze one of the previous nights images and line the telescope up for you.
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Old 18-09-2017, 06:01 PM
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RickS (Rick)
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James,

It doesn't matter if you have a permanent set up or not. Once you're polar aligned a goto with the RA and Dec of your target will get your mount to point roughly in the right direction. The "trick" for getting the alignment perfect is using plate solving software. A plate solver can analyse an image and tell you exactly where your telescope was pointing (and the image scale and orientation of the camera.) This can be used to find out where your telescope was pointed last night and it can be used to check you're pointing at exactly the same place tonight.

Here's some info on plate solvers from the SGP documentation:

http://mainsequencesoftware.com/Cont...teSolvers.html

Cheers,
Rick.
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Old 18-09-2017, 06:14 PM
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traveller (Bo)
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As Rick said, plate solving is the key.
But you can also do this manually if you are using a guidescope. Provided there is good optical alignment between the guidescope and the imaging scope, you can get fairly good image matches between nights.
The image stacking software will then be able to take care of the rest.
Bo
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