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NGC7822 in SHO


Tommohawk
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Hi all.

I saw a couple of lovely renditions of this online somewhere and thought I'd give it a go. Switching from my PDS200 with CC to the widefield refractor is easy now as they both use 55mm backfocus. That said I noticed the spacing was about 1mm out so removed a thin (0.25mm) plastic spacer from between the camera and the EFW - forgetting that my very dodgy flats would then be even more dodgy!

Actually this turned out to be a blessing in disguise, because my NB flats have always been a problem - and it turns out this may be to do with the non-linear nature of the camera. I re-did the flats using the NINA flats wizard and set the mean ADU much lower - about the same as the mean ADU of the lights. And finally after 4 years of banging my head against a wall I finally have NB flats that don't overcorrect vignetting - hurrah!

OIII for this was stretched to blazes so lots of blue haloes - I've reduced the worst of them.  I didn't really like the periphery of this image either - we have LED streetlights now and pretty sure this causes very slight gradients which is enough to muck up faint data. So I did a cropped square which I think frames quite nicely.

Anyhow, about 3 hours per filter, and pretty pleased with the outcome - as ever more data would be nice! Guiding was amazingly good (for me anyhow!) at 0.49" RMS. I'm now using multi star align on PHD2 and maybe this makes some difference?

HEQ5, Sharpstar Mk1 61 EDPH, ZWO MkII NB filters, NINA, APP, PS. (300sec subs, -20C)

Thanks for looking - -grateful for any comments. 

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12 hours ago, Clarkey said:

Great image 👍. The multi star guiding definitely helps in my opinion.

Thanks. Re multi star guiding wonder if it also makes it easier to pick up guiding after any passing clouds? Although guiding was good there was one brief period where star was lost, but seemed to resume OK.

12 hours ago, Catanonia said:

Nice, I am trying this tonight with the RASA 8, if only the clouds would stay away

Thanks. RASA 8 - that's the tool for the job! Look forward to seeing your results.

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2 hours ago, Tommohawk said:

Thanks. Re multi star guiding wonder if it also makes it easier to pick up guiding after any passing clouds? Although guiding was good there was one brief period where star was lost, but seemed to resume OK.

Thanks. RASA 8 - that's the tool for the job! Look forward to seeing your results.

Didn't realise how faint this object is in comparison to NGC7000 etc etc.  Well I got 4.5 hours of good 5min subs with the RASA 8, hope it works out ok

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