The Needle Galaxy in Coma Berenices

NGC 4565 is a barred spiral located about 40 million light years away. NGC 4565 is the largest member of the Coma I galaxy group. To the upper left of the main galaxy is a group of faint (around magnitude 19) background galaxies (A-G in the enlarged crop here). Most if not all of these objects are part of a cluster located 2.2 billion light years away. The same area also hosts an extended radio source (X), and a candidate quasar (Q), located 6 and 10 billion light years away, respectively.


Exposure: Total exposure time about 12.5 hours. 272:33:31:40 x 2 mins LRGB. All bin 1x1. Captured January to April 2017.
Light pollution: Bortle 7-8 (white zone, NELM 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: CPC1100 fork mount
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 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

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

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
Saturation boost with Curves Trans

7. Color Combine
LRGB merge

8. Fixes in Photoshop
Radial blur in color layer on colored halos
Color Select, Minimum Filter to shrink a few large stars
Create artificial flat and subtract to remove background artifacts

9. Final
Downsize 50% and save as JPG