This is another image from telescope live, NGC 1566. This was a really tough image to stack, as there was a ton of uncalibrated dust motes in a lot of the frames, and there were a lot of dark artifacts on the brightest stars. Additionally, almost half of the frames had airplane trails that wouldn’t calibrate out. I ended up using the Adam Block method of selective rejection to try and remove a lot of the worst parts during stacking, and it seemed to work pretty well. Again, SPCC seems to be doing a better job of color calibration overall, however, I had to do some manual color balancing to remove the red cast.
An island universe of billions of stars, NGC 1566 lies about 60 million light-years away in the southern constellation Dorado. Popularly known as the Spanish Dancer galaxy, it’s seen face-on from our Milky Way perspective. A gorgeous grand design spiral, this galaxy’s two graceful spiral arms span over 100,000 light-years, traced by bright blue star clusters, pinkish starforming regions, and swirling cosmic dust lanes. NGC 1566’s flaring center makes the spiral one of the closest and brightest Seyfert galaxies. It likely houses a central supermassive black hole wreaking havoc on surrounding stars, gas, and dust. In this sharp southern galaxy portrait, the spiky stars lie well within the Milky Way.
Image:
You can access a full-quality PNG here: https://live.staticflickr.com/65535/52787823749_5e7df393d1_o.png
Annotated Image:
Full-quality image here: https://theastroenthusiast.com/wp-content/uploads/2023/03/SpanishDancerAnnotated.jpg
Closeups:
Below you can see the detail in the irregular galaxy PGC 416409. It’s remarkably far away and small, so getting this much detail in an image this wide was a nice surprise.
I spent a lot of time carefully deconvoluting the core of the galaxy, and I think it paid off quite nicely. The dark dust lanes appear to be extremely sharp, and the little pink patches of h-alpha gas shine through very well.
Details
Telescope: Planewave CDK24
Camera: FLI PL 9000
Filters: Astrodon LRGB 2GEN
Location: El Sauce Observatory, Río Hurtado, Coquimbo Region, Chile
Date of Observations: 12/16/2021, 1/6/2022, 1/7/2022, 1/29/2022, 9/20/2022, 10/16/2022, 10/19/2022, 10/22/2022, 10/24/2022, 11/1/2022
L: 20 x 600s (3h 20min)
R: 20 x 600s (3h 20min)
G: 20 x 600s (3h 20min)
B: 20 x 600s (3h 20min)
Processing: Pixinsight
Credits: Data: Telescope Live; Processing: William OstlingProcessing
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
- LRGB combination
- Noise reduction
- Color adjustment
- Backround adjustment
- MMT sharpening
- Saturation enhancement
- LHE
- Slight stretching