Dust lanes in the Sculptor Galaxy

Here’s another image from telescope live: NGC 253. This was a really challenging but also really rewarding dataset to wrestle with. The biggest problem with the data was that half of it was at BIN2, which meant that registration introduced a lot of weird artifacts around the stars, and drizzle couldn’t really get rid of them. I had to pioneer a Multiscale approach to the stacking of the dataset, which got rid of most of the bad areas. The end result was totally worth it – the detail in the core of the galaxy and dust lanes is really just incredible.

I really recommend zooming in to see the smaller background galaxies in this image – some of the spirals are large enough to actually have some detail!

NGC 253 is not only one of the brightest spiral galaxies visible, it is also one of the dustiest. Discovered in 1783 by Caroline Herschel in the constellation of Sculptor, NGC 253 lies only about ten million light-years distant. NGC 253 is the largest member of the Sculptor Group of Galaxies, the nearest group to our own Local Group of Galaxies. The dense dark dust accompanies a high star formation rate, giving NGC 253 the designation of starburst galaxy.

Image:

Full-quality image here: https://live.staticflickr.com/65535/52751760195_c53ec16cfa_o.png

Annotated Image:

Full-quality image here: https://theastroenthusiast.com/wp-content/uploads/2023/03/NGC253_annotated-scaled.jpg

Details:

Telescope: Planewave CDK24
Camera: FLI PL 9000 
Filters: Astrodon LRGB 2GEN
Location: El Sauce Observatory, Río Hurtado, Coquimbo Region, Chile
Date of Observations: 7/28/2020, 10/30/2022, 2/7/2023
L: 10 x 600s (1h 40min)
R: 12 x 600s (2h)
G: 10 x 600s (1h 40min)
B: 14 x 600s (2h 20min)
Processing: Pixinsight
Credits: Data: Telescope Live; Processing: William Ostling

Processing:

Pre-processing and Stacking
- Images were cosmetic corrected for hot pixels
- The subframes were weighted, registered, normalized, integrated, and drizzled in WBPP
Preparation of all frames:
- Stacking artifacts were cropped
- RGB Channels were combined to create an RGB image
- RGB image was plate solved
- Starless DBE was applied to L, RGB as follows:
      - Starnet 2 was applied to a clone of the target image, creating an image with stars and an image without stars
      - DBE was applied on the starless image to create a background model
      - The background model was subtracted from the stars image
- the RGB image was photometrically color calibrated using SPCC and clipped H values were fixed with the repaired HSV separation script
Deconvolution of the luminance
- a PSF was created using the dynamic PSF process
- Linear starnet was applied to create a starless image and a star mask
- the linear image was duplicated, stretched, clipped, and convoluted to create a mask
- The starless image was deconvoluted using the RVC algorithm
- the stars were added back in
- A low contrast mask was created and applied to the luminance image
- Noise Xterminator was applied with strength 73 and detail 0
- DeepSNR noise reduction was applied to RGB
Stretching
- The Luminance image was stretched using HT and GHS
- The RGB image was stretched using ArcsinH and GHS
Non-linear adjustments
- Saturation adjustments on RGB
- LRGB combination
- Star reduction
- HDR MST
- Saturation Adjustment
- LHE
- Background fix
- Sharpening using MMT and unsharp mask
- LHE
- Saturation Adjustment
- Dark Strucutre Enhancement