NGC 2359 – Thor’s Helmet
 Foraxx Palette |
 RGB with SHO Enhancement |
 Hubble Palette |
 Modified Hubble Palette |
Click image for full size version
March 14, 2026
NGC 2359 is also known as Thor’s Helmet (also catalogued as IC 468, Sh2-298, and Gum 4) and is an emission nebula in Canis Major. The powerful Wolf-Rayet star WR7 near the centre of the nebula is causing the gases to glow. That star is thought to be in a brief pre-supernova stage, and could explode in the cosmically-not-too-distant future. This nebula contains hundreds of solar masses of ionized gases (the gases that are glowing), along with hundreds of thousands of solar masses of unionized material. The age of the nebula is uncertain, with estimates ranging from 78,500 to 236,000 years.
This object is thought to be similar to the Bubble Nebula, but the energy from WR7 has blown the gas in Thor’s Helmet into more complex shapes. Thor’s Helmet also contains much more oxygen structures than the Bubble Nebula. In the natural-colour image at top left, oxygen gives the teal-coloured structure while hydrogen and sulfur provide the reds. The other images are fals-color palettes, except for the stars which are from the natural-colour image.
I was pleasantly surprised that I could capture this from my home observatory. It was scraping the trees in the south, with the sky awash in light pollution from a nearby auto mall.
Tekkies:
Acquisition, focusing, and control of Paramount MX mount with N.I.N.A., TheSkyX. Guiding with PHD2. Primalucelab low-profile 2″ Essato focuser, ARCO rotator and Giotto flat panel. Equipment control with PrimaLuce Labs Eagle 4 Pro computer. All pre-processing and processing in PixInsight. Acquired from my SkyShed in Guelph. Below average transparency and seeing. Acquired under a moonless sky from March 8 – 13, 2026.
Celestron 14″ EDGE HD telescope at f/11 (3,931 mm focal length) and QHY600M-SBFL camera binned 2×2 with Optolong filters.
12 x 1m Red = 0hr12m
11 x 1m Green = 0hr11m
11 x 1m Blue = 0hr11m
30 x 5m S2 = 2hr30m
30 x 5m Ha = 2hr30m
30 x 5m O3 = 2hr30m
Total: 8hr04m
Preprocessing: The WeightedBatchPreProcessing script was used to perform calibration, cosmetic correction, weighting, registration, local normalization, integration, and auto-cropping.
Colour masters: A natural-olour master was made from the Red, Green and Blue masters using ChannelCombination in RGB mode. A Hubble palette master was made the same way using the Sulfur, Hydrogen and Oxygen masters.
Gradient Removal: DynamicBackgroundExtraction was applied to the RGB and Hubble palette masters.
Colour Calibration: ColorCalibration was used to calibrate the RGB master. Background neutralization was applied to the Hubble palette master
Deconvolution: BlurXterminator was used on the RGB and Hubble palette masters with Automatic psf at default settings.
Linear Noise Reduction: NoiseXterminator was applied to the RGB and Hubble palette masters with settings Amount=0.9 and Iterations=3
Star Removal: StarXterminator was used to remove the stars from the RGB and Hubble palette, with default settings. Only the RGB stars-only image was preserved.
Stretching: MultiscaleAdaptive Stretch was applied to the RGB and Hubble palette masters to make pleasing images. Approximate background level after the stretches was 0.10 for both images.
Nonlinear Processing
Nonlinear Noise Reduction: NoiseXterminator was applied to the RGB and Hubble palette with settings Amount=0.9 and Iterations = 3
Contrast Enhancement: LocalHistogramEqualization was applied twice to the Hubble palette master. A Contrast Limit of 1.5 and 1 iteration was used for each LHE application (scale 150, strength 0.35; scale 50, strength 0.22).
Sharpening: A mask was used to select brighter regions of nebulosity in the Hubble palette master for sharpening with MultiscaleMedianTransform (Layers 2 – 43with strengths of 0.07, 0.05 , 0.03 and 0.03, respectively).
Narrowband Channel Extraction: In preparation for making additional images, the red, green and blue colour channels were extracted from the Hubble palette master. They were renamed S, H, and O, respectively.
Enhanced RGB Image Creation: The stretched S, H and O masters were combined with the RGB image using Jurgen Terpe’s CombineHaWithRGB script to add Ha mainly to the red channel, with a little contribution to the blue. This was followed by the CombineRGBandNarrowband script to add S to the red channel and O to both the green and blue channels.
Foraxx Palette Image Creation: The S, H and O masters were combined with Paul Hancock’s Foraxx Palette Utility script.
Modified Hubble Palette Image Creation: A copy of the Hubble palette image was adjusted using the CurvesTransformation process.
Hubble Palette Colour Adjustments: Jurgen Terpe’s SelectiveColorCorrection script and the CurvesTransformation Hue tool were used to adjust the colour tones in the Hubble palette image.
Star Processing and Restoration: HistogramTransformation was used to stretch the stars-only RGB image, followed by CurvesTransformation through a star mask to boost saturation using the Saturation slider. The stars were added back into the four master images using the PixelMath expression combine(starless, stars, op_screen()).
Final Steps: Background, nebula and star brightness, contrast and saturation were adjusted using several iterations of CurvesTransformation, with masks, as required. ICCProfileTransformation (sRGB IEC61966-2.1; Relative Colorimetric with black point compensation) was applied prior to saving as a jpg.
Incredible!
Thanks!