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Old 19-08-2019, 09:49 PM
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lazjen (Chris)
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lazjen is offline
Join Date: Dec 2012
Location: Flaxton, Qld
Posts: 1,669
I've had a few hours over the last few nights to proceed further. I at least now have manual dome rotation so I can get to anywhere I want.

After much stuffing around, I came to the conclusion that I couldn't get the PA sorted using PHD drift align with the out of collimation RC10. I also discounted using the methods in the hand controller to do PA once I realised that I had no idea how to work out what dots on the screen were what stars it was asking for, even if they didn't all look like comets.

So, I've switched to the Sharpstar 107PH until I sort out the RC10, so testing at 700mm instead of 2000mm. Although I still managed to stuff around getting it done, it was of a lesser quantity.

I got the PA to 1.6' for the night using PHD Drift Align - I'll refine it more another time. Also, I need to experiment more with the PHD settings to find the most ideal setup.

I took a 10 min Ha exposure of M16 for a test. I then discovered I had some terrible tilt in the system:

Click image for larger version

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I took 2 more images with similar results. For the first 2 I used 6 sec guiding (because that was the max I had in the dark library at the time). For the 3rd image, I used 10 sec guiding after creating the missing darks. I forgot to keep the PHD logs, but the guiding seemed "mostly fine", as in if I improved PA and tweaked the settings I could probably do much better.

I think I know what's causing the tilt (OAG is biggest suspect) and the next night I'm out I'll be trying to sort that out. If it wasn't for the tilt and some dodgy focus because of it, the 3 images I took would have been ok-ish.

I'd like to do a longer exposure for a test, but even at 0 gain, the ASI1600 was saturating parts of M16. I'll have to do a fainter/darker area to see how that goes sometime.
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