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M42, the Great Nebula in Orion, 1,500 light years away.  M43 is visible lower left.  A region where stars are being formed.  The young bright stars at centre left of this image are called the Trapezium, and are ionizing the molecular cloud which the nebula is embedded in.  This gas glows with the deep red colour characteristic of ionised hydrogen.  Wisps of dark dust clouds can be seen in this image as well.


Image info

Telescope:  Skywatcher 8" f/5 Newtonian

Focus:  Prime focus

Camera:  SAC7B, uncooled

Exposure:  various, mosaic of 7 images, including one of the Trapezium region taken at a shorter exposure in order to avoid burning out the image in this bright region.  This part of the image was then composited in using Photoshop.

Date:  1st Dec 2002

Processing:  Acquired in Astrovideo as FITS.  Stacked and mosaicked in Iris.   An LRGB image with the red image image used as the luminance component.  This luminance image was histogram stretched logarithmically to enhance fainter details.  Colour saturation enhanced using the Multiple Luminance Layering technique.


In hindsight, the use of the red component as luminosity only worked well because the mosaicking resulted in a high resolution overall image.  As discussed in the Image Processing section, the red component is sub-sampled by the camera and is of inferior resolution to the green component.


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