The NGC 1060 Galaxy Group in Triangulum

This grouping is cataloged as WBL 085 (Catalog of Nearby Poor Clusters of Galaxies) and as LGG 72 (Lyons Groups of Galaxies), and is dominated by the large lenticular galaxy NGC 1060. One article reports that there is a 250 kiloparsec bridge of hydrogen gas between NGC 1060 and the elliptical galaxy NGC 1066 on the left of the image, but that's hard to imagine as redshift measurements suggest that the two galaxies are separated by 20 million light years. NGC 1060 is an AGN (active galactic nucleus) galaxy, with a 7.4 kiloparsec jet and associated radio emission. The galaxy group has about 15 members, and is located about 235 million light years away. The field is also filled with wisps of IFN, or “integrated flux nebulosity,” the dust and gas of the Milky Way.


Exposure: Total exposure time about 26 hours, 556:67:72:80 x 2 minutes LRGB. All bin 1x1. Data collected September to November 2019.
Light pollution: Bortle 7-8 (white zone, NELM about 4.5)
Seeing: Average FWHM of subs around 2.4 arcsecs
Image scale at capture: 0.6 arcsecs/pixel = f/5.7
Scale of presentation: 1.2 arcsecs/pixel (50% of full scale)

Equipment:
Scope: C11 (standard, not Edge) with Celestron 0.63 reducer
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 5nm Ha/SII, 3nm OIII, Type IIe LRGB
Rotator: Optec Pyxis 2", connected via Andy Galasso's 0.4 driver (Optec Pyxis Rotator AG)
Focuser: Rigel Systems GCUSB nStep motor with driver version 6.0.7 on stock Celestron focuser
OAG: Orion Thin OAG
Guide cam: Lodestar (first generation). 4 second exposures
Automation SW: Sequence Generator Pro 3.0.0.8
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 1.86

1. Calibration
BatchPreProcessing with flats and bias, using Cosmetic Correction with master dark
Blink to preview and reject a few frames
Subframe Selector for luminance to confirm selections and weight by FWHM and SNR
StarAlign to register frames

2. Stack and Mure Denoise
Image Integration on each channel
Mure Denoise on each channel
RGB Combination for RGB frames
Dynamic Crop

3. Luminance Linear Processing
Dynamic Background Extraction
Deconvolution on luminance frame, using a mask created manually in Photoshop so that only the galaxies I wanted were sharpened.

4. Luminance Stretching
Histo Trans x 2
Masked Stretch
Curves Trans
TGV Denoise
Aggressive Multiscale Median Transform to remove lumpiness in background, using an inverted and blurred luminance frame as a mask to protect highlights
(I made a second, less stretched version to use as a luminance star image)

5. RGB Linear Processing
Dynamic Background Extraction
Photometric Color Calibration

6. RGB Stretching
Histo Trans
Masked Stretch
Curves
Desaturate background with Curves, using an inverted Range Mask
(I made a second version using masked stretch only, to use for color in the luminance star image)

7. Color Combination
LRGB Combination of luminance and RGB images

8. Star Reduction
Deconvolution to sharpen small stars very slightly

StarNet to remove stars. This badly damaged many galaxies, so I modified the StarNet image in Photoshop so that I removed only the medium-sized stars:
a. Layer StarNet image over LRGB image
b. Select>Color Range to select only the medium-sized stars in the LRGB image
c. Adjust the selection size with Select>Expand/Contract
d. Create a mask from the selection, and slightly blur it with Gaussian Blur
e. Use the mask to mask in the StarNet image, and thus erase the medium-sized stars.

For the brightest star, create an 8 bit copy of the image, select the star with the selection tool, then Filter>Distort>Pinch by 50%, and copy and paste the star back into the 16 bit image

An artificial flat, created in Photoshop, was used around one bright star at the bottom, to remove reflections. Otherwise I left the background alone, since much of it appears to be IFN.

Repair comatic blue halos: On medium-sized stars, Filter>Radial Blur on color layer. On brightest stars, select blue halo with the wand tool and shift hue in color saturation to match the rest of halo.

Save as TIFF and move back into PI

9. Final
Final Histogram Transformation
ICC Profile Transform to sRGB
Resample to 50% of scale
Save as JPG