Sunday, October 13, 2013

Bubble Nebula at Calstar 2013




See more at

Taken on two night at Calstar, Oct 4 & 5, this is from a stack of just 4 subs. The focus was good, tracking was good, exposures were good.  Thus all frames were used in the stack.

I had some issues with hot pixels showing up after the stacking, so I went back to calibration and reworked the bad pixel map in Maxim.  Added a few new pixels that weren't covered and things looked much better.

Also, I created master files for all the darks in the library for all temperatures from 2C to 29C.  I don't think I'll need new darks for a long while!  Nearly every temperature has at least 5 files and some have several dozen.  Making the masters required a lot of processing time, but once they were done, it will be easy to reference them.

Processing, I used my basic PI steps:
Crop, DBE, Masked Stretch
Then I restretched in the Histogram Tool to reset the black point and tweak color balance.
Created luminance mask, stretched it, then used it to run TGVDenoise on the weaker areas.
Flipped the mask to highlight the bright areas, ran MT and then Unsharp Mask to tighten the bloating stars and recover details.
Flipped the mask again and used Curves to bring down the lowest parts in both RGB and Saturation.  This effectively increases the contrast.

No light pollution filter was used on the shot.  I can see more faint nebula and dust.  The only filter used was the B+W 486.