NGC2403 - Image for 2006

Spiral Galaxy in Camelopardalis

Uploaded 12/29/06

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This years rendition of this splendid face on spiral in Camelepodarus incorporates the latest processing techniques, and plenty more color data for a rich and very low noise presentation. NGC2403 is a low surface brightness inclined Sc spiral, rated at an integrated magnitude of 8.9, which is spread out to a rather thin 25 arcseconds in size - about half a degree long here. North is up in this view, and the galaxy is inclined about 5 degrees from face on for our view from the Earth. Additionally, this galaxy is very dust obscured, with a B-V index of.47, meaning it photographs as nearly pure yellow. Histogram equalization was able to easily correct for this discoloration, presenting the galaxy in a more true color appearance.

Note the warped extensions in the outer most blue arms. The lower left side warps down, and the upper side warps up. Is this faint outer spiral detail, or an anomalous distortion? You decided. This is a standard LRGB image, with no extra Halpha added. This is coming next. I've left the brightness of the sky background slightly light so you can see the faint arms and some of the dim 18th magnitude background galaxies. And to answer a question that everyone asks me - Why are the diffraction spikes oriented 45 degrees from North - South? Because my square tube on the 12.5" has the vanes for the spider mounted from corner to corner on the box. Some day I may change this.

Processing: The L channel was enhanced to bring up the faint arms by layering screened duplicate over the image, with a negative image of the galaxy itself as a layer mask. To do this totally undocumented trick and use an actual image for a layer mask, first make a normal all white or black layer mask. Click the mask while holding the Alt key down. Your image on the screen becomes the mask. Paste over it a negative of the actual image. It converts to greyscale automatically, and BECOMES the layer mask. Click back on the main image to see the result. You can now vary the contrast of the image layer mask with Levels or Curves and achieve a totally spectacular masking effect.

Instrument: 12.5" f/5 Home made Newtonian Mount: Astrophysics 1200 QMD CCD Camera: SBIG 10XME NABG with Enhanced Water Cooling Guider: SBIG ST4 w/Lumicon Newt Easy Guider Exposure: LRGB = 80:40:40:40 (RGB Binned 2x2) AstroDon RGB Combine Ratio: 1: 1.05: 1.11 Location: Payson, Arizona, Elevation: 5150 ft. Sky: Seeing FWHM = 4.5 arcsec (Maxim DL - 10min subframe), Transparency 8/10 Outside Temperature: 35 F CCD Temperature: -30 C Image Processing Tools: Maxim DL: Calibration, Deblooming (Starizona Debloomer), aligning, stacking Gralak's Sigma: Stacking PixInsight: Curves, Deconvolution, noise reduction Photoshop CS2: Curves, Color Correction, Gradient removal (Grad Xterminator), Cleanup HOME GALAXIES EMISSION NEBS REFLECTION NEBS COMETS GLOBULARS OPEN CLUST PLANETARIES LINKS


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