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The Hole in the Trees Skybox | all galleries >> Deep Sky >> Planetary Nebulae > BV 5-1
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BV 5-1

Böhm-Vitense 5-1 in Cassiopeia


Böhm-Vitense 5-1 (PK 119+00.1, PN G119.3+00.3) was cataloged by Erika Böhm-Vitense in 1956. It is a bipolar planetary in which the molecular and the ionized gas are seen nearly edge-on. It is thought to be an evolved planetary and has apparent dimensions in H-alpha of about 50 x 20 arc seconds. (Thanks to Jim Shuder for this information.) This is a bicolor Ha:OIII image, using separate blends of Ha and OIII for luminance and color on the nebula, with RGB for the star field. The area is suffused in faint Ha clouds, but I found it impossible to bring that out without blowing out the nebula.


Exposure: Total exposure time about 15 hours. 21:21 x 20 mins Ha:OIII, 20:18:26 x 2 mins RGB. All bin 1x1. Captured August to November 2019.
Light pollution: SQM ~18.2 (Red/white zone border, Bortle 7-8, NELM at zenith about 4.5)
Image scale at capture: 0.6 arcsecs/pixel = f/5.7
Scale of presentation: Full size

Equipment:
Scope: C11 (standard, not Edge) with Celestron 0.63 reducer imaging at f5.7
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 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 3.0.3.169
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 1.88

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

2. Stack and Mure Denoise
Blink to preview frames and remove some bad images
Subframe Selector to weight by SNR and FWHM
Image Integration
Mure Noise Reduction on each channel
Channel Combination to merge RGB channels
Dynamic Crop

3. Narrowband Linear Processing
Dynamic Background Extraction
Deconvolution on narrowband images

4. Narrowband 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 x 2
Create star mask with Advanced Star Mask script
Multiscale Linear Transform to sharpen stars slightly

7. Color Combine
Create luminance and color images from narrowband data
Luminance: PixelMath max command with Ha and OIII
Color: Use PixelMath to map narrowband Ha:OIII:(0.85OIII+0.15Ha) to R:G:B
LRGB Combination

8. Merge Narrowband and RGB Stars
Curves Transform to match background of RGB stars image to narrowband image
In Photoshop, layer nebula onto RGB stars image with a mask.
Radial blur on color layer to reduce comatic blue halos on stars near edges of FOV

9. Final
Crop
ICC Profile to sRGB
Save as 100% quality JPG


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Chris Sullivan 27-Dec-2019 18:23
This is great. I imaged this earlier this year and couldn't find any other image with the faint extensions at the bottom left, from bottom left to bottom right beyond oxygen, the extra lip of hydrogen at the top right as well as the tiny arc of hydrogen at the top left edge of the hydrogen. Your image has it all and confirms what I found in my image (and is a much better image to boot). Great work and thanks for posting!