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North American and Pelican Nebulae, Nikhil Joshi

North American and Pelican Nebulae

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North American and Pelican Nebulae, Nikhil Joshi

North American and Pelican Nebulae

Equipment

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Acquisition details

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Description

Version C uses non-linear pixel math in the color channels to bring out details.

Red = 1.0*Ha

Green = .03*O3+0.6*exp(-1*(Ha-0.75)^2/.1)+0.6*exp(-1*(Ha-0.98)^2/.02)

Blue = 0.1*O3+0.2*exp(-1*(Ha-0.2)^2/.1)+0.3*exp(-1*(Ha-0.98)^2/.02)

The various exponential terms are gaussians that emphasize a selected brightness band in each channel. For example, in the green the term +0.6*exp(-1*(Ha-0.75)^2/0.1) boosts the brightness values centered on 0.75 with a standard deviation of +/-0.3. This boosts the signal for the nebulosity near the "west coast" of "Mexico" and the back of the Pelican's head. The Blue channel is similarly boosted.

The terms +0.6*exp(-1*(Ha-0.98)^2/.02) in the green channel (and similarly in the blue channel) are used to reduce ringing for the brighter stars. The gaussian is centered on the very highest values in the star cores with a narrow StDev. The Blue and Green is boosted in this way to match the Ha signal in the star cores, thereby reducing the ringing.

Comments

Revisions

  • North American and Pelican Nebulae, Nikhil Joshi
    Original
  • North American and Pelican Nebulae, Nikhil Joshi
    B
  • Final
    North American and Pelican Nebulae, Nikhil Joshi
    C

Histogram

North American and Pelican Nebulae, Nikhil Joshi

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Cloudy Nights