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How can I know that my images are truly stacked?  

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(@paul-from-northern-mi)
White Dwarf Customer
Joined: 6 months ago
Posts: 14
April 2, 2020 17:41  

Yesterday I ended up with disappointing results in an Orion photo processing.

There was 1 oddity that I wanted to check into to see if the reason for the disappointing results has to do with the images not being combined together.

The oddity was that the frame edge didn't have any kind of discernable rounding due to the natural earth movement applied to the star field.

I stacked 38 light frames.  Each frame was exposed for 1 minute, and there was 3 seconds of pause between shots.

Should I be seeing rounding on the integrated image within 40 minutes of exposure time?

Maybe I shouldn't but I just want to rule this out.


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(@vincent-mod)
Quasar Admin
Joined: 3 years ago
Posts: 1746
April 4, 2020 16:22  

Do you have an example you can upload here? If it's stacked and you preview it in the preview window, a stretch should be applied showing you a lot more signal compared to a single frame. 1 min is a quite low exposure time though, but it still should show this effect.


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(@paul-from-northern-mi)
White Dwarf Customer
Joined: 6 months ago
Posts: 14
April 4, 2020 17:20  

Thank you Vincent:  What kind of example would you be looking for?  A jpeg of the completed project or a FITS after integration?


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(@vincent-mod)
Quasar Admin
Joined: 3 years ago
Posts: 1746
April 4, 2020 18:00  

You can post a jpeg of the final integration here, just to get a better idea of what you mean.Thanks!


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(@paul-from-northern-mi)
White Dwarf Customer
Joined: 6 months ago
Posts: 14
April 5, 2020 17:53  

Vincent,

Here is the photo processed through.

I was hoping for better nebulosity and the result was somewhat underwhelming.  As mentioned above the reason I was wondering if this even stacked properly is that I didn't notice any rounding on the corners on the uncropped photo.

Orion1min 1stLNC it2 lpc cbg cbg csc St

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(@vincent-mod)
Quasar Admin
Joined: 3 years ago
Posts: 1746
April 8, 2020 12:22  

That looks fine to me, it's definitely stacked otherwise you would likely not see the surrounding nebulosity and a single sub is probably way darker isn't it? Getting more out of the nebulosity requires way more data, longer exposures per frame and ofcourse things like narrow band filters will help you a lot as well. But you will have to get towards 5 min and longer regarding exposure time.


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