Polar Ring Galaxy in Pisces

NGC 660 is a member of the M74 group of galaxies, and is located about 40 million light years away. It was formed about a billion years ago from a collision of two galaxies or the capture of material from a passing galaxy. The galaxy group at lower left is about 730 million light years away. Most of the other background galaxies are over 1 billion light years away.


Exposure: Total exposure time about 12.2 hours. 268 x 2 mins Lum, 33:33:33 x 2 mins RGB. All bin 1x1. Captured August to October 2018.
Light pollution: SQM ~18.2 (Red/white zone border, Bortle 7-8, NELM at zenith about 4.5)
Image scale at capture: 0.6 arcsecs/pixel = f/5.7
Scale of presentation: 1.2 arcsecs/pixel (50% reduction)

Equipment:
Scope: C11 (standard, not Edge) with Celestron 0.63 reducer imaging at f5.7
Mount: Paramount MX+, connected via ASCOM Telescope Driver 6.1 for TheSkyX, with MKS 5000 driver 6.0.0.0
Camera: SXVR-H694, connected via SX ASCOM driver 6.2.1.17140 (SX 1.2.2 also installed)
Filter wheel: Atik EFW2 with 7x1.25 carousel and Artemis 2.4.3.0 driver
Filters: Astrodon Type IIi LRGB
Rotator: Optec Pyxis 2", connected via Andy Galasso's 0.4 driver (Optec Pyxis Rotator AG)
Focuser: Rigel Systems GCUSB_nStep with driver version 6.0.7
OAG: Orion Thin OAG
Guide cam: Lodestar (first generation). 4 second exposures
Automation SW: Sequence Generator Pro 3.0.0.4 beta
Guide SW: PHD2.6.3, connected to guide cam via native SXV driver
ASCOM: ASCOM 6.3.0.2831
Platesolving: PlateSolve 2, failover to local Astrometry.net 0.19 server
Collimation: Metaguide 3, using ASI120MM connected via ZWO Direct Show driver 3.0.0.2

Processing Workflow by Workspace in PixInsight 1.85

1. Calibration
BatchPreProcessing with flats and bias, using Cosmetic Correction with a master dark.

2. Stack and Mure Denoise
Blink to preview frames and remove some bad images
Image Integration
Mure Noise Reduction on each channel
Channel Combination to merge RGB channels
Dynamic Crop

3. Luminance Linear Processing
Dynamic Background Extraction
Deconvolution, using Dynamic PSF, multiple iterations of Star Mask to create a deringing support image, and stretched luminance as a mask.

4. Luminance Stretching
Histogram Trans
Curves Trans
Noise Reduction with TGV Denoise and Multiscale Median Transform (following David Ault’s Astro Imaging Channel tutorial.)
Local Histogram Equalization on galaxy core

5. RGB Linear Processing
Dynamic Background Extraction
Photometric Color Calibration

6. RGB Stretching
Histo Trans and Curves Trans
Noise reduction with TGV Denoise and Multiscale Median Transform

7. Color Combine
LRGB merge

8. Fixes in Photoshop
Radial blur to reduce coma on stars near edges of FOV
Color Select, Minimum Filter to shrink a few large stars
Create artificial flat and subtract to remove background artifacts

9. Final
Very slight Multiscale Median Transform to sharpen core
Downsize 50% and save as TIFF
In Photoshop: Save to Web, unchecking ICC Profile, save as 100% quality JPG