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The Hole in the Trees Skybox | all galleries >> Deep Sky >> Planetary Nebulae > Abell 72
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Abell 72

Planetary Nebula PK 59-18.1 in Delphinus

The nebula is OIII colorized to teal blue, layered onto the RGB star field. The Ha data was identical to the OIII but much dimmer, and so was not used.

Exposure: Total exposure time about 10.3 hours, 28 x 20mins OIII, [29 x 20 mins Ha not used], 20 x 2 mins per channel RGB. All bin 1x1.
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 Procedure: Pixinsight 1.85, some touchup in Photoshop CS2
1. Batch Preprocessing for calibration (darks [for narrowband only], bias, flats) and registration, with Cosmetic Correction using master dark (75 dark frames)
2. Blink to preview and reject a few frames, Subframe Selector to confirm selections and weight evenly between FWHM and SNR
3. Image Integration using linear fit clipping
4. Linear Processing for narrowband:
a. Mure Denoise, Multiscale Median Transform denoise with luminance mask, TGV Denoise
b. Crop
c. Deconvolution with Dynamic PSF and deringing and luminance masks
d. Dynamic Background Extraction
5. Linear Processing for RGB:
a. Mure Denoise
b. LRGB Combination
c. Crop
d. Dynamic Background Extraction
e. Background Neutralization
f. Color Calibration
6. Stretch Narrowband with Histogram Transformation and Curves Transformation, Deconvolution (parametric) with luminance mask for additional sharpening, slight extra TGV Denoise, colorize OIII to teal blue with Pixel Math
7. Stretch RGB using Jon Rista’s technique to preserve star color
8. In Photoshop, layer OIII onto RGB starfield with mask, cleanup blue comatic halos with Radial Blur, downsize 50%

comment | share
Ken Zaret16-Apr-2019 02:31
This looks like a Rapatronic image of the first millionth of a second after Trinity, but in color. Great job!
Sakib 29-Jan-2018 13:52
This is one of the best images of Abell 72, so much structure!