Celestial hemisphere:  Northern  ·  Constellation: Cygnus (Cyg)  ·  Contains:  NGC 6910  ·  The star Sadr (γCyg)
The Butterfly Nebula (IC1318) imaged in SHO, Andrew Klinger

The Butterfly Nebula (IC1318) imaged in SHO

The Butterfly Nebula (IC1318) imaged in SHO, Andrew Klinger

The Butterfly Nebula (IC1318) imaged in SHO

Equipment

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Acquisition details

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Description

Towards the constellation Cygnus lies an abundance of ionized gas and dust. Here we are looking at the Gamma Cygni Nebula, and more specifically the Butterfly Nebula, showing off its two wings filled with glowing nebulosity. The brightest star in this field, Sadr, is the center of the cross-shaped constellation of Cygnus.

This false-color image represents the Hydrogen and Sulfur emissions as the warmer colors and the Oxygen emissions as blues.

Equipment:  
OTA: William Optics GT81 w/0.8x reducer (382mm fl at f/4.7)
74mm aperture stop-down ring (brings scope to f/5.2)
Mount: Orion Sirius EQ-G (HEQ-5)
Guidescope: Orion 50mm guidescope
Guiding camera: Orion StarShoot Autoguider
Imaging camera: ZWO ASI1600MM-Cool

Accessories:
QHYCCD PoleMaster

Software:  
SGP
PHD2
CdC
PixInsight

Acquisition:  
Location:
Joshua, TX (Bortle 4)
Dates: 9/6/20, 10/28/21, 11/6/21
Gain: 200 Offset: 50
Camera temp: -10C for Ha, -20C for SII/OIII
Sii: 51x300" Astrodon 3nm 1.25"
Ha: 65x300" Astrodon 5nm 1.25"
Oiii: 49x300" Astrodon 3nm 1.25"
Total integration time: 13hr 45min
64x darks per calibration (master from library)
30x flats per calibration
200x bias per calibration (master from library)

Preprocessing:
Batch PreProcessing script to generate calibrated images
StarAlignment
ImageIntegration
DynamicCrop

Luminance Processing:
Duplicated master Ha to use as the Luminance
Deconvolution
ArcsinhStretch
HistogramTransformation
Created a duplicate starless version using StarNet++
Combined the starless version with the image using PixelMath expression "F=0.4; (1-(1-$T)*(1-s)*F)+($T*~F)". (s=starless photo)
HistogramTransformation
LocalHistogramEqualization
MultiscaleLinearTransform
CurvesTransformation
MorphologicalTransformation to reduce star size
UnsharpMask to slightly sharpen stars

Preparing separate Sii, Ha, and Oiii linear masters for tonemapping (applied to each master individually):
Removed stars by running LinearStarNet script
Convolution
HistogramTransformation
HDRMultiscaleTransformation on SII and Ha

Combined prepared Sii, Ha, and Oiii masters with ChannelCombination:
R: Sii
G: Ha
B: Oiii

Tonemap Processing:
CurvesTransformation to balance colors
Invert>SCNR>Invert with mask to remove magentas
HistogramTransformation to balance colors
More masks and curves to tame Sadr
StarNet to remove leftover star artifacts
CurvesTransformation with ColorMasks to balance colors

Combined Tonemap with Luminance using LRGBCombination:
CurvesTransformation for slight contrast and saturation
MorphologicalTransformation for slight star size reduction
ACDNR for slight NR
Resampled to 60% for web posting

Comments

Sky plot

Sky plot

Histogram

The Butterfly Nebula (IC1318) imaged in SHO, Andrew Klinger

In these public groups

Narrowband imaging