M42 in Orion, LLRGB experiment

[Amaranthus]

Thanks to some tips from Ivo on creating a synthetic luminance channel, and after studying all of the Startools tutorials judiciously, I think I'm finally getting the hang of this! The more I use StarTools, the easier and more natural it becomes. The learning curve is not steep, but the depth in this software is incredible. I'm still swimming in the shallows, of course

Anyway, here is the great nebula in Orion, taken just before first light on 29 August using an ED80T CF astrograph with an Orion Starshoot G3 mono CCD. My 'real AP' learning kit. This is definitely an experimental image, prior to my work on some objects with deep integration times (LRGB data collected, now acquiring some Ha for these).

M42_HDR_Composite-Bin-Driz-5-2.jpg (194.86 KiB) Viewed 5153 times

Orion was low in the morning sky, and I only had less than 2 hours to capture all my data due to the balance of needing Orion to rise to a sufficient altitude, and to avoid the brightening astronomic dawn. The image is composed of the following:
Lum = 18 x 30 sec + 23 x 10 sec
R, G & B = 15 x 30 sec for each channel

Full capture/processing details and higher rez version here: http://www.astrobin.com/117345/

I then created a synthetic luminance channel using an exposure-based weighting of the L30, L10 and R, G and B luminances. The L and RGB chrominance channels were then processed separately before final combination. All subs were unbinned (35 minutes total integration). Guided using PHD2 with an ASI120MM-S camera and an OAG.

Captured and pre-processed with flats (light box), bad pixel map and bias in Nebulosity. Post-processed in StarTools (of course!).

This camera/astrograph is heavily undersampled at 4.6 arcseconds per pixel (and the StarShoot G3 chip is small and yields relatively low resolution images, at 752 x 582 pixels). To overcome these constraints, I used drizzle alignment in Nebulosity (this brought it up to an equivalent 2.5 megapixel image). However, there is some graininess in the image due to a lack of sufficient subs, especially in the lower signal areas (outer regions).

But overall, I deem this experiment to have been a success.

[Amaranthus]

Updated the image - you can see both versions on Astrobin: http://www.astrobin.com/117345/B/

[admin]

Very nice!
If I would have one niggle with the image it would be the coloring - most of the stars are white, while the complex is somewhat purple in hue. Did you use the Color module at the end (before switching Tracking off?) Depending on your RGB data, you may even be able show the greenish core of M42!

[Amaranthus]

I actually spent quite a bit of time on the colour module at the end, but I used artistic detail aware mode instead of scientific, which had the effect of whitening most of the stars (but gave nicer hues to the nebulosity). It was a conundrum - scientific gave better stars, artistic gave better results elsewhere in the image. But I think it comes down to my experience and playing more with the possibilities. One thing I'd like to do is use eXcalibrator to set colour via the G2V index - I just haven't had time yet to get it working. I hope that will help! But I think this is mostly down to my personal learning-by-doing training