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Test - M81 and M82 10s subs with ZWO ASI 183

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Disclaimer - My processing skills are at best, average. This thread is by no means a definitive test. Its just my observations.

I took some long exposures in Narrowband at 600s using the ASI183mm Pro camera and found that sometimes I could eliminate the Amp Glow from the middle right hand side using Darks and Flats and sometimes I could not. No idea why! Any help appreciated.

I found it easy to remove the glow when imaging at under 120 seconds a sub. This gave me the idea of trying to eliminate amp glow and noise by imaging at short, 10 second exposures, to see the results.

The one thing I failed to realise is the amount of disk space needed to process 200 x LRGB from a 20Mp camera ? The Registered and Calibrated files where 60Gb each!!

Processing on a External USB3 disk on a USB3 port on i7 with SSD and 16Gb RAM took best part of an hour. Not counting the restarts due to having other things running or lack of disk space etc.


Here is the result. Slightly cropped as it was taken over several nights and I did move the camera.

200 x LRGB at 10s

ZWO ASI 183mm Pro

TS 65/420 Quadruplet

Mesu 200

SGPro, Pixinsight.


Thanks for looking.

M81 and M82 ZWO ASI183mm Pro and TS 65 420 Quadruplet.jpg

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Looks good. That's about 2.2 hrs total integration time if I have done my sums right?

It is a totally subjective comment, with no science behind it but the level of detail in the galaxies to me  doesn't look that dissimilar to what would be achieved with fewer but longer individual subs? I guess you would have to run back to back comparisons with your rig to see if it has improved on the noise issue.

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Thanks tomato,

Yes, 2.2 hours but there is a delay between each sub. Then dithering set every 4th sub. I think this image took around 6 hours in total to collect the data.

I agree, maybe a 1 or 2 minute sub at 2.2 hours comparison is needed. I will try that in the coming weeks.  

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I think that's a great result!. I'd be happy with that.

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It looks like your flats didn't really fit to your images as you have some brighter circles in the left right part. Also consider dithering more as the noise has a distinguishable pattern. Overall I thing that if you'll add couple of hours you'll get a really nice image. 

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I redid the flats last night, after posting this. I will try a reprocess when I have time. I also have dither set to small, I will increase it.

Thanks for your thoughts and comments. Much appreciated.

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