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Strategies for stacking more and more subs?

Mark KnechtMark Knecht
in PixInsight
I'm wondering if anyone has a rigorous method for how to stack more and more subs over time?

I'm working on a little project with my new Advanced VX mount and DSLR. My scope is 250mm F/5 and I'm imaging IC342 specifically because it's difficult. I'm at the point after three evenings where I have over 600 1-minute subs with good overall results. I've stacked the first evening by itself, then the first two nights, and then all 3 nights. It all works and the galaxy is becoming (somewhat) more visible. All good.

However what is recommended when I have a huge number of 1-minute subs - say 3000 or more? The stacking time becomes the limiting factor.

I thought possibly I should start stacking in smaller groups, say 60 representing 1 hour, and then stacking those 1 hour subs to make the final image. It doesn't make sense to me to mix 1 hour subs with a few 1 minute subs but I figure someone coming before me probably knows the right technical answer.

Thanks in advance for any ideas.

Cheers,
Mark

Comments

  • BlockHeadBlockHead
    I have a terrible thought. Would it be so horrible to take 3 minute exposures? 
    The right answer is to really do as you are doing- to integrate the complete set and take advantage of the normalization, weighting and rejection that comes with it. So my recommendation is to minimize the total number of subframes. There is a a point of diminishing returns... you can probably see with your three nights that tells you really how many hundred minutes really makes sense to do.

    -the Blockhead 
  • Mark KnechtMark Knecht
    3 minute exposures are an interesting question. Having just gotten this AVX mount I'm working my way up in terms of exposure times. I do not currently have any guiding hardware so I'm limited to how well I do polar alignment and after that how well the mount actually works unguided. My 1-minute exposures are pretty good at least as far as some simple experiments go, like using subframe selector and just reviewing the specs. I see no significant degradation at 1 minute vs 20 or 30 seconds.

    I'll look into doing some longer exposures on something easier than IC342 just to see how it works out.

    My hope is in the next month or two to add guiding and possibly dithering. 

    Thanks for the response.
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