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The Hole in the Trees Skybox | all galleries >> Deep Sky >> Planetary Nebulae > HDW 6
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Hartl Dengel Weinberger 6 in Gemini

HDW 6 (PNG 192.5+07.2) is a highly evolved, extremely faint planetary of about 76 arcseconds in diameter. The luminance here was made from a 70/30 Ha/OIII blend since Ha was about 2.5x the strength of OIII. The color is Ha:OIII:OIII mapped to Red:Green:Blue. Very little information is available about this object, and there appears to be only >one other image, from 1996.

Exposure: Total exposure time about 17.30 hours, 26:26 x 20 minutes Ha:OIII, bin 1x1. Data collected from January to March 2019.
Light pollution: Bortle 7-8 (white zone, NELM about 4.5)
Seeing: Average FWHM of subs around 2.45 arcsecs
Image scale at capture: 0.6 arcsecs/pixel = f/5.7
Scale of presentation: 0.6 arsecs/pixel (full scale)

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 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
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 1.86

1. Calibration
BatchPreProcessing with flats, darks and bias, using Cosmetic Correction with master dark
Blink to preview and reject a few frames
Subframe Selector 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
Dynamic Crop

3. Linear Processing
Dynamic Background Extraction
Deconvolution on Ha with Dynamic PSF and star mask for deringing support. Masked in using mask created in Photoshop.

4. Stretching
Histo Trans x 3
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

5. Channel Blending
For Luminance: PixelMath, 70/30 blend of Ha/OIII
For Color: PixelMath, Ha:OIII:OIII mapped to Red:Green:Blue
LRGB Combination to create (Ha-OIII)HOO

6. Star Reduction and Background Removal
Three star masks for small, medium and large stars
Morphological Transform to erode stars
Multiscale Median Transform to sharpen stars

7. Final
Final Histogram Transformation
Save as JPG

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Sakib 26-Nov-2019 21:42
This is really nice, the exquisite creme de la creme of PN imaging! Keep going after the unphotographed ones!