Multi night dark question

[nmoushon]

So I was able to get out on last night as well as on the 9th and get about an hour worth of data of M42 on each night. I also got darks for each night seeming that the difference in temperature from the two nights was over 30! So the first image is of the first night and the second image is a combined stack of both nights worth of data. The two night stack, though having more detail, seems to have more noise than the single night stack. I'm a bit confused as to why this is. I processed them both in the same way so no idea why. Also theres an arc of something at the bottom left of the pictures. Anyone know whats causing that? At first I thought it was the moon because it was just past full on the 9th but there was no moon last night and it still showed up. So can't blame it on the moon.

[martin_h]

What did you use to stack the images?

[nmoushon]

I used DSS. Put the subs and darks from both nights in one process.

[Ant]

I've only just learnt how to stack two nights data...

Open your lights and darks (you really need to start taking flats as well) as you would normally.

Then just under the list of files a second tab appears.

Thanks to Martin for the tip.

Click on the tab and open lights/darks and flats.

If you have a third night then use the next tab along.

This way DSS knows which darks to put with which lights etc...

Jope that helps - but by looking at your final image I would say that you really needed flats on the second set!

Cheers

Ant

[Ags]

Ant that is very helpful :-) thanks

[nmoushon]

Thank you so much Ant! I never noticed those tabs down there. Will reprocess the data tonight and see what I come up with. In regards to flats, its not as bad as it looks. Most of that is LP. I'm in the suburbs of Chicago which, according to NatGeo, has the worst LP in the U.S. So I have to drive 45min to get to a site that is just bearable to take pics. To get to the darkest skies in my state I have to drive 2hrs. But I do need flats. Just need to figure out a good way to do it out in the field. Any suggestions?

[Ags]

You could get one of those electroluminescent flat panels?