Hemisphere:  Southern  ·  Constellation: Canis Major (CMa)  ·  Contains:  IC 468  ·  NGC 2359
Thor's Helmet (NGC 2359) imaged in SHO, 


            Andrew Klinger
Thor's Helmet (NGC 2359) imaged in SHO
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Thor's Helmet (NGC 2359) imaged in SHO

Thor's Helmet (NGC 2359) imaged in SHO, 


            Andrew Klinger
Thor's Helmet (NGC 2359) imaged in SHO
Powered byPixInsight

Thor's Helmet (NGC 2359) imaged in SHO

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 Pro  ·  PHD2  ·  Cartes du Ciel  ·  EQMOD  ·  PixInsight

Filters: Astrodon OIII 3nm  ·  Astrodon SII 3nm  ·  Ha 5nm

Accessory: PoleMaster

Dates:March 7, 2018

Astrodon OIII 3nm: 16x300" (1h 20') (gain: 200.00) -20C bin 1x1
Astrodon SII 3nm: 20x300" (1h 40') (gain: 200.00) -20C bin 1x1
Ha 5nm: 93x300" (7h 45') (gain: 200.00) -20C bin 1x1

Integration: 10h 45'

Darks: ~64

Flats: ~32

Bias: ~200

Avg. Moon age: 20.33 days

Avg. Moon phase: 68.83%

Bortle Dark-Sky Scale: 4.33

Basic astrometry details

Astrometry.net job: 2053012

RA center: 7h 17' 59"

DEC center: -13° 5' 2"

Pixel scale: 1.688 arcsec/pixel

Orientation: 89.982 degrees

Field radius: 0.725 degrees

Resolution: 2371x1985

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

Data source: Unknown



OTA: William Optics GT81 w/0.8x reducer (382mm fl at f/4.7)

Mount: Orion Sirius EQ-G (HEQ-5)

Guidescope: Orion 50mm guidescope

Guiding camera: Orion StarShoot Autoguider

Imaging camera: ZWO ASI1600MM-Cool







Location: Flower Mound, TX for Ha (Bortle 7), Atoka, OK for Oiii (Bortle 3), and Caddo National Grassland, TX for Sii (Bortle 3)

Dates: 2/7/18, 2/17/18, 3/2/18, 3/7/18

Gain: 200 Offset: 50

Camera temp: -20C

SII: 20x300" Astrodon 3nm 1.25"

Ha: 93x300" Astrodon 5nm 1.25"

OIII: 16x300" Astrodon 3nm 1.25"

Total integration time: 10hr 45min

64x darks per calibration (master from library)

32x flats per calibration

200x bias per calibration (master from library)


Batch PreProcessing script to generate calibrated images




DynamicCrop (BIG crop!)


LinearFit to Ha

Duplicated all three masters. One set used for tonemap creation, and one set used for a synthetic Lum.

Preparing masters for the tonemap (all processes applied to each master individually):

TGV and MMT noise reduction (via Jon Rista's method)

Histogram Transformation x2 (linear -> non-linear)

Created a starmask and removed stars via MMT and MorphologicalTransformation

Tonemap processing:

SHO masters assigned to RGB channels respectively to create a color image

2 different curves adjustments (a and b channels) using ColorMask Script to target individual colors and adjust them to an aesthetically pleasing composition

Invert -> SCNR green -> Invert -> SCNR green to remove magenta and green colors



L Processing:

Created a synthetic luminance with PixelMath using the following formula: Ha*0.2 + Oiii*0.7 + Sii*0.1


HistogramTransformation x2 (linear -> non-linear)


Combined the Luminance with the Tonemap using LRGBCombination

Post-combination adjustments:


SCNR green


MMT for slight noise reduction

HistogramTransformation to move black point in

MorphologicalTransformation for slight star size reduction

Resampled to 60% for web posting


Sky plot

Sky plot


Thor's Helmet (NGC 2359) imaged in SHO, 


            Andrew Klinger