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View Full Version here: : RA or DEC drift?


meade expert
24-01-2010, 05:43 PM
I have stacked 10 images with slightly oval stars of the horsehead to determine which drift is the culprit? (no alignment done in DSS)
I think its RA drift but perhaps someone could conform this?

Bassnut
24-01-2010, 06:17 PM
Is the pic up/down aligned with RA or DEC ?.

meade expert
24-01-2010, 06:26 PM
DEC as it (the DSLR)was slightly inclined towards the left in the focuser of a SN10

AlexN
24-01-2010, 06:36 PM
To accurately work it out, what you need to do is put your camera square in the focuser, so that up/down in the image corresponds to RA +/- and left right corresponds with DEC N/S.. Find out by taking a short exposure while pushing the up arrow on your mounts controller, you will then know that this direction is North, and is Declination. take another short exposure while pusing the left button on your controller, you will now know that is East, and is RA... Take some images, if the image drifts left/right, you know its RA, if it drifts up/down, you know its dec...

Happy hunting.

rat156
25-01-2010, 09:05 PM
The mount is not polar aligned well enough to do long exposure stuff.

You can see the field rotation in the image.

That said it's probably dec, and your scope needs balancing as there seems to be some backlash in the dec gear, making it bounce.

Cheers
Stuart