Willow House Terlingua Rosette Nebula

My first narrow band image of the Rosette Nebula. With a 99% full moon even Terlingua skies need a little help. The two approaches two sky glow or light pollution reduction in an image are:

  • Broad band which reduces the wavelengths of the worst light pollution. Most light is passed to the sensor giving images a reactively natural color balance with moderate reduction of sky glow.
  • Narrow band which only passes a few specific wavelengths of light. This approach is generally used with emission nebulas which glow at specific wavelengths of excited Hydrogen (red) or Oxygen (blue green).

Narrow band imagers often use monochrome sensors. In this image I've used one shot color sensor and a NB filters which passes more than one wavelength. A relatively natural color balance achieved by photometric color correction in post processing.

The Rosette Nebula captured from Willow House in Terlingua on the evening of 2021-03-27. A William Optics RedCat 250/51mm telescope, Optolong L-eNhance dual NB filter, ZWO ASI533MC one shot color camera cooled to -10C, on a Sky-Watcher AZ EQ5 mount, all controlled by a ZWO ASIAIR astro controller. The L-enhance captures both Ha red and Oiii bluegreen bands. The Oiii band falls between the blue and green filters of the Bayer array in the OSC sensor. With the blue capturing only about 50% of the light and green capturing 90% and blue only 50%. I've reprocessed the image to adjust for this and remove the green cast in the nebula.

Here is the original version without adjusting for the Bayer array color sensitivity to Oiii

Here are some behind the scenes photos from Willow House the night this image was made.

Setup for imaging at sunset:

Moon setting over Willow House:

All packed up in time for the sunrise:

Content created: 2021-03-29 and last modified: 2021-04-03




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