NGC 2244 and Rosette

[traveller]

This target has been eluding me for a couple of years but finally managed to get some decent data during the new moon a couple of weeks ago.
I combined 100 x 150 sec at 1600 plus some limited old data of 90-120 secs. I did my best to remove the gradient from the right side of the image but there still seem to be too much blue cast. Maybe I should try and just stack the 150 sec images and see how I go :question:
Comments welcome.
Thanks
Bo

[Placidus]

Hi, Bo,

That's really pretty.

The blue gradient toward the right is subtle. We notice it stops at a sharp edge about 10% from the right hand side. That suggests that it is due to the scope not quite pointing to the same spot on different nights (a very good thing, as it helps with all kinds of other problems), and there being slightly different conditions on the two nights (could be darks, temperature, altitude of the object, moon or sky glow, etc etc).

As mentioned, it's not so very severe, but if it bothered you, the trick would be to normalize the background to be the same, perhaps even down to removing the gradients on a per-sub basis, before stacking. Certainly set the zero point on the histogram very accurately for each channel of each image before stacking.

One again, a lovely image.
Best,
M & T

[cometcatcher]

That's a very nice Rosette Bo.

[RickS]

Looks pretty good, Bo!

[Andy01]

Nice Rosette Bo, not too many about in RGB this season - well done! :thumbsup:

[traveller]

Thanks M&T. Yes it was a 3 night project so there was a bit of misalignment, plus temp differentials. I haven't done any gradient removal before stacking yet, but might give it a go when I get around to it. I am just doing basic DSLR RGB at the moment. More fun to come when I get a mono CCD...



Thanks Kevin, having enough data to play with helps ;)



Thanks Rick, I think I can try and shrink down the stars a bit next time.



Thanks Andy, no mono CCD for me yet, so RGB will do for now. :)