Link to Inverted Images
This is the first detailed image of KK 26 (PNG 139.3+04.8), which was discovered in 1995 during a search for nearby dwarf galaxy candidates. At the time, it was catalogued as Camelopardalis C, and in 2000 it was included in the Karachentsev list of candidate dwarf galaxies as KK 26. However, in an emission line study done later that year with the 3.5-meter Apache Point telescope, it was determined to be a bipolar planetary nebula. As near as I can tell, only survey images have captured this object until now. It shows quite well in the IPHAS H-alpha image, and faintly even in the Palomar Deep Sky Survey blue image. The HASH planetary nebula database reports a diameter of 106 arcsecs. I can’t even guess at its magnitude.
Exposure: Total exposure time about 23 hours, 31:30 x 20 minutes Ha:OIII, 27:26:24 x 2 minutes RGB. All bin 1x1. Data collected from September to December 2022.
Light pollution: SQM ~18.38 (Bortle 7-8, NELM at zenith about 4.5, Red/white zone border.)
Seeing: FWHM of integrated luminance 2.5 (Ha) and 2.3 (OIII) arcsecs
Image scale at capture: 0.6 arcsecs/pixel = f/5.7
Scale of presentation: 0.9 arcsecs/pixel (75% of full scale).
Equipment:
Scope: C11 (standard, not Edge) with Celestron 0.63 reducer
Mount: Paramount MX+, connected via ASCOM Telescope Driver 6.2 for TheSkyX, with MKS 5000 driver 6.0.0.0
Camera: SXVR-H694, connected via SX ASCOM driver 6.2.1.18212 (SX Windows Drivers 15.26.50.450 [i.e., version 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 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 4.2
Guide SW: PHD 2.6.11, connected to guide cam via native SXV driver
ASCOM: ASCOM 6.6 SP1
Platesolving: ASTAP, failover to local Astrometry.net 0.19 server
Collimation: Metaguide 3, using ASI120MM connected via ZWO Direct Show driver 3.0.0.2
Processing Software: Pixinisight, Photoshop CS2
Processing Workflow by Workspace in PixInsight 1.8.9:
1. Calibration
Calibration with WeightedBatchPreProcessing with flats and bias, using Cosmetic Correction with a master dark
Blink to preview and reject a few frames
Weighting, registration and integration with WBPP
2. Linear Processing
RGB Combination for RGB frames
Dynamic Background Extraction on narrowband and RGB
ImageSolve RGB, then run Spectrophotometric Color Calibration, using Average Spiral Galaxy white reference
BlurXterminator on narrowband and RGB
NoiseXterminator on narrowband and RGB
3. Lum/Narrowband Processing
Histo Trans x 3
Curves Trans
StarXterminator to create starless image
4. Colorization of Narrowband Image
Blend images in PixelMath, using Ha for red, OIII for green and blue
Curves Trans to shift nebula toward blue in narrowband image (pulling down green and pulling up blue, while keeping the LRGB balanced)
Mild TGVDenoise
Final Curves Trans
5. RGB Processing
Histo Trans
Curves Trans to boost saturation
Histo Trans
Curves Trans for brightness
StarXTerminator to create starless and stars-only (star mask) images
PixelMath to subtract starless image from RGB image, adding a pedestal. This removes circular artifacts left over from flat calibration, which is caused by imaging with a moving-mirror SCT.
6. Image Combination
PixelMath to blend stars-only image and colorized narrowband image using formula ((1-$T)*(stars_only))+$T
In Photoshop, layer the resulting nebula_plus_stars image onto the RGB image using a mask
7. Final
Final Histogram Transformation
ICC Profile Transform to sRGB
Save as JPG
