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The Hole in the Trees Skybox | all galleries >> Deep Sky >> Planetary Nebulae > Abell 5
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Abell 5

PK 141-7.1 in Perseus

Bicolor Ha/OIII image, using Ha as luminance. I had to toss half the Ha data I collected due to hazy conditions during many nights, and I collected only two hours of OIII before the target went into the trees from my observatory. The OIII is extremely faint.

Exposure: Total exposure time about 8.7 hours, 22 x 20mins Ha, 6 x 20 mins OIII. All bin 1x1. Captured over 8 nights from November 2017 to January 2018.
Light pollution: Bortle 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)

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
Camera: SXVR-H694, connected via SX ASCOM driver (SX 1.2.2 also installed)
Filter wheel: Atik EFW2 with 7x1.25 carousel and Artemis 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 with driver version 6.0.7
OAG: Orion Thin OAG
Guide cam: Lodestar (first generation). 4 second exposures
Automation SW: Sequence Generator Pro beta
Guide SW: PHD2.6.3, connected to guide cam via native SXV driver
Platesolving: PlateSolve 2, failover to local 0.19 server
Collimation: Metaguide 3, using ASI120MM connected via ZWO Direct Show driver

Processing Workflow by Workspace in PixInsight 1.85

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

2. Stack and Mure Denoise
Blink to preview and reject a few frames
Mure Denoise

3. Luminance Linear Processing
Dynamic Crop
Dynamic Background Extraction

4. Stretching
Histo Trans
Masked Stretch
Curves Trans
Noise Reduction with TGV Denoise and Multiscale Median (following
David Aultís Astro Imaging Channel tutorial).

5. Color
Merged narrowband channels in PixelMath: mapped Ha to R, OIII to green, 85% OIII and 15% Ha to blue
LRGB Combination: used Ha as luminance
Downsize 50% and save as JPG

other sizes: small medium large original auto
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