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Contains:  IC 1274, IC 4684, IC 4685, Lagoon Nebula, M 8, NGC 6523, NGC 6526, NGC 6530, NGC 6544, NGC 6546, NGC 6559, The star 11Sgr, The star 7Sgr, The star 9Sgr
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The Lagoon Nebula (M8) imaged in SHO-RGB, 


            Andrew Klinger
The Lagoon Nebula (M8) imaged in SHO-RGB
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The Lagoon Nebula (M8) imaged in SHO-RGB

Technical card

Imaging telescopes or lenses:William Optics GT-81

Imaging cameras:ZWO ASI1600MM-Cool

Mounts:Orion Sirius EQ-G (HEQ5)

Guiding telescopes or lenses:Orion 50 mm Guide Scope

Guiding cameras:Orion Star Shoot Auto Guider

Focal reducers:William Optics Flat 6A

Software:Sequence Generator ProPHD2Cartes du CielEQMODPixInsight

Filters:Astrodon OIII 3nmZWO B 1.25"ZWO G 1.25"ZWO R 1.25"Astrodon SII 3nmHa 5nm


Dates:June 11, 2018July 31, 2018June 24, 2020

ZWO B 1.25": 30x180" (gain: 76.00) -10C bin 1x1
ZWO G 1.25": 27x180" (gain: 76.00) -10C bin 1x1
Ha 5nm: 74x300" (gain: 200.00) -10C bin 1x1
Astrodon OIII 3nm: 26x300" (gain: 200.00) -10C bin 1x1
ZWO R 1.25": 33x180" (gain: 76.00) -10C bin 1x1
Astrodon SII 3nm: 25x300" (gain: 200.00) -10C bin 1x1

Integration: 14.9 hours

Darks: ~64

Flats: ~30

Bias: ~200

Avg. Moon age: 16.08 days

Avg. Moon phase: 35.85%

Bortle Dark-Sky Scale: 3.33

Basic astrometry details job: 3640443

RA center: 18h 6' 11"

DEC center: -24° 3' 43"

Pixel scale: 2.528 arcsec/pixel

Orientation: 52.498 degrees

Field radius: 1.531 degrees

Resolution: 3530x2560

Locations: Atoka dark site, Atoka, Oklahoma, United States; Backyard, Flower Mound, Texas, United States

Data source: Traveller


In this rendition of The Lagoon Nebula, I blended natural color stars into the false-color image of the nebula. The warmer tones represent where Sulfur and Hydrogen lie in the nebula, while the blues represent the Oxygen emissions.

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

DeepSkyDad Autofocuser AF1
QHYCCD PoleMaster


Flower Mound, TX for Ha(Bortle 7) - 2018 data
Atoka, OK for RGB(Bortle 3) - 2018 data
Ft. Griffin State Historic Site, TX for OIII and SII(Bortle 2) - 2020 data
Dates: 6/11/18, 7/31/18, 8/1/18, 6/24/20
Gain: 200 Offset: 50 for Ha
Gain: 76 Offset: 15 for RGB
Camera temp: -10C
SII: 25x300" Astrodon 3nm
Ha: 74x300" Astrodon 5nm
OIII: 26x300" Astrodon 3nm
R: 33x180"
G: 27x180"
B: 30x180"
Total integration time: 14hr 55min
64x darks per calibration (master from library)
30x flats per calibration
200x bias per calibration (master from library)

Batch PreProcessing script to generate calibrated images

Luminance Processing:
Duplicated the master Ha to use as the luminance
ArcsinhStretch and HistogramTransformation to bring to non-linear
HDRMT on the core area
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)
MultiscaleLinearTransform for sharpening
MorphologicalTransformation using a star mask to completely remove the stars

Preparing separate Sii, Ha, and Oiii linear masters for tonemapping (applied to each master individually):
TGV noise reduction (via Jon Rista's method)
ArcsinhStretch and HistogramTransformation to bring to non-linear
HDRMT on the core area (Ha and OIII only)
Removed stars via StarNet++

Preparing RGB image:
ChannelCombination to create the color image
SCNR Green
ArcsinhStretch and HistogramTransformation to bring to non-linear
SCNR Green
CurvesTransformation for saturation
SCNR Green (I'm really making sure no stars are green since that is all I'm using this for)
StarNet++ to remove stars and create an RGB star mask

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

Tonemap Processing:
HistogramTransformations to balance colors
CurvesTransformations using ColorMasks
Invert>SCNR Green>Invert to remove magenta in core area
CurvesTransformations for saturation adjustments

Combined Tonemap with Luminance using LRGBCombination

Added in RGB stars using the RGB star mask and PixelMath to add the RGB star-only image to the tonemap

MorphologicalTransformation to slightly reduce star sizes
CurvesTransformation to saturate stars
UnsharpMask to slightly sharpen stars
A few cosmetic adjustments to fix introduced RGB artifacts
Resampled to 80% for web posting



Andrew Klinger
License: None (All rights reserved)

Sky plot

Sky plot


The Lagoon Nebula (M8) imaged in SHO-RGB, 


            Andrew Klinger

In these public groups

Narrowband imaging