M42 - Orion Nebula in Narrowband (+animated gif version) (Doug Gray)

M42 - Orion Nebula in Narrowband (+animated gif version)

I took a first pass at Orion back in November with my DSLR and was pretty happy with the result at the time. However after spending all winter practicing with the ASI294MM and improving my mono narrowband post-processing skills, I decided it was time to revisit and see how far I've come. The creative color choice (started in SHO and spun the hue slider till I found what I was looking for) is the most obvious difference, but there's at least a dozen things I'm doing differently now and a few things I know I still need to address.

Happy: I can resolve the Trapezium cluster, and lots of detail in the core without needing to combine different exposure lengths. The narrowband filters bring out both more detail and interesting structures I could not see in broadband. Rotating the OTA between sessions has removed the weird mini-difraction spikes around bright stars.

Sad: My flattener has some tilt that I have not been able to correct, and I don't have a good way to correct it on the bench. RGB stars bloat more than I want when I turn up the gain, so I've ended up with fewer in the field as a compromise. The Running Man Nebula is very faint in this version and I don't know why.

Final
Original
B

B

Description: M42 has so much signal in each channel that as I was editing I could not decide on the color pallette, so I had the idea to show all options in an animation. I looked around and it seems equinoxx has done something similar with this target to highlight different channels/options.

What I've done here is start with a SHO version and sample every 4 degrees of a 360 rotation in the hue channel of HSV color space. Our eyes are most sensitive to the green channel, so this gives each emision line a chance to shine as we go from SHO to HSO to HOS.

I've put these into an animated gif, but it turns out that this format is limited to 256 quantized colors and this kind of animation is terrible for that compression scheme (I need all the colors!). If astrobin ever supports better video formats I may try again with finer increments, but I'll need to learn photoshop scripting first as I would not want to do this manually again.

Uploaded: ...

GIF conversion techniques

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Status	Advanced success
Started	...
Astrometry.net job	4350689
PixInsight job	ZASAUF9XZWYL2X7688J0K4DZYXMUQU9W
PixInsight queue size	n/a
PixInsight stage	n/a

RA (center)	05h34m53s.27
RA (top/left)	05h33m45s.70
RA (top/right)	05h30m15s.79
RA (bottom/right)	05h36m00s.74
RA (bottom/left)	05h39m31s.56

Dec (center)	-05°25′12″.1
Dec (top/left)	-06°42′45″.7
Dec (top/right)	-04°46′06″.7
Dec (bottom/right)	-04°07′30″.8
Dec (bottom/left)	-06°04′06″.8

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