NGC 1499 / Sh2-220 California Nebula - first post here and first acceptable NB

[Herbert West]

Hello!

This is my interpretation of NGC 1499 and my first astrophoto that I managed to decently process (after butchering a few LRGB and one NB image).

Yes, it’s closer to monochromatic- on purpose. Far too many Californias are red smears, devoid of details. Which is a shame, as there’s lots of interesting things going on in this nebula. I didn't want to smother them with too intense color. Chromatically, this was supposed to be like dusty desert with a splash of pale, blue sky. Yes, that means loosing some information that could be conveyed with richer color, but, ultimately, I like it as it is. And I enjoy being a contrarian, sometimes 🙂

Aside from this somewhat controversial color, I did my utmost to not overprocess the image and, I think, it went well. All my previous attempts have been way overdone but this one may be somewhat undercooked 🙂

Acquisition:
Backyard, rural Poland, Bortle 4. During four cloudless nights about four weeks ago; nearly full moon. Ha 80*300s, Sii 85*300s, Oiii 95*300 s (or thereabouts). Nearly full Moon. Darks, flats, dark flats. I could use more Oiii data.... twice what I got.

Gear:
TS65Q APO 65/420 apochromatic quadruplet, SW EQ6 Pro, ASI1600MMP, Baader Oiii, SII, Ha, EFW, EAF, ASIAir, guidescope 50/240 & ASI120M mini.

Processing done entirely in Pixinsight.

Preprocessing:
•WBPP: Calibration, CosmeticCorrection, Registration (Drizzle Data for Ha)
•NormalizeScaleGradient for S and O, ImageIntegration
•DrizzleIntegration for Ha (scale: 2x, Drop Shrink: 0.7)

Luminance:
•DynamicCrop
•DynamicBackgroundExtraction
•very slight TGV denoise and MMT denoise (except for the 1st wavelet layer) with masks
•Deconvolution in three steps; first step with StarMask for the largest stars only, second with StarMask expanded to medium-sized stars, third step with the same mask; no LUM mask used, just proper Global Dark and Global Light settings; stopped and backtracked a little when some slight artifacts started to appear on bright nebulosity edges
•MMT sharpening for the small-scale structures (wavelet layers 2 and 3, Dyadic scale), no noise reduction step
•Rescale 50%.

SHO
•Rescale preprocessed Ha by 50%
•MureDenoise with custom settings on Sii and Oii; strongly decreased amount and iteration count at 20.
•DynamicCrop
•DynamicBackgroundExtraction
•Gentle TGV denoise and MMT denoise on S and O (except for the 1st wavelet layer) with masks.

LRGB
•LRGBCombination with Ha from the "Luminance" step as L, R=Sii, G=Ha (from the "SHO"), B=Oiii
•SCNR (removed 100% green, deliberately)
•HistogramTransformation without masks, in three steps, used only the Midtones slider; left slider untouched to preserve background as the luminance and chromatic noise was quite fine; contrast later adjusted with some ExpotentialTransformation and Curves.
•Two iterations of ExponentialTransformation with PiP to finish the stretch
•Curves: saturation boost
•StarXterminator: remove stars
•Curves: slight R and B tweaks on the separate stars image
•Curves, starless picture: very slight overall RGBK adjustment
•Curves with masks made from Sii data, Oiii data and extracted LUM, properly stretched and contrast boosted: saturation and colors tweaks, slight contrast adjustment on the nebula itself.
•Tiny bit of LocalHistogramEqualization on 16 and 32 kernel sizes, 1.1 contrast and 1.0 amount.
•PixelMath to put the stars back in
•EzStarReduction (1 iteration)
•A very small amount of DarkStructureEnhance scrip

Resized ~80%.

Please fell free to point out any and all imperfections- you'll be doing me a favor!

Starless (made with StarXterminator):

[The Lazy Astronomer]

This is probably my favourite image I've seen of this target (I agree with you about how it's normally represented: bland pinkish-red blob).

The puritans may scoff at the colour rendition, but I think it makes it much more interesting.

You've inspired me to add it to my own list for the future. ☺

[scotty38]

Nice image. I am also interested in the PI process with me being fairly new to it so more for me to think about there too.

[Herbert West]

Thank you for your kind words @The Lazy Astronomer I've also had little interest in this nebula. Until I saw some really good pictures of it :-)

[Herbert West]

10 minutes ago, scotty38 said:

Nice image. I am also interested in the PI process with me being fairly new to it so more for me to think about there too.

Thanks. Even before I got a camera I had been pondering the processing question. It quickly became obvious that it has to be PI at some point. There's so much talk about the dreaded PI learning curve that I decided to just get it over with and bought it. Thus, it's been my first and only processing software.

[scotty38]

1 minute ago, Herbert West said:

Thanks. Even before I got a camera I had been pondering the processing question. It quickly became obvious that it has to be PI at some point. There's so much talk about the dreaded PI learning curve that I decided to just get it over with and bought it. Thus, it's been my first and only processing software.

Pretty much the same here. I had never even looked through a scope at the beginning of the year so yes I jumped in with both feet too!

[Herbert West]

I couldn't stop myself from fiddling with it, so this is the final version (I hope so).