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NGC2264+colour.jpg

70 x 300s H-alpha, 16 x RG&B, 300s each, no darks (hot pixel removal in Astroart instead).

Subframes were stacked in Astroart, the outputs converted to TIF files and then colour-composited in PaintShop Pro.

The colour data was a bit of a pig to process with the software I have.  First of all it became apparent that 300 second subs probably weren't long enough. I had to stretch the resultant stacks quite a way to get any decent detail, which introduced more noise than I really wanted. Then the blue colour stack turned out to be a slightly different size to the others, despite all being full frame without any need to resize. I always refocus between filter changes as the colour correction on my old Vixen 114 ED refractor is not brilliant, so I guess this was the cause, particularly on the blue channel.  This made it difficult to stack the images for colour composition.  I did my best to manually rotate and resize in PaintShop, but the stars still show some odd haloes where the channels didn't quite line up.

I made two colour images, one created by the addition of green and blue channels (20 x 300s subframes for each) to the H-alpha image above, which was used as the red channel for an RGB composite. This was a rather violent red, as anticipated, so I blended it with an HaRGB stack, which was the usual washed-out pink.  The blend gave a reasonable depth of colour. The blue brilliance of the brighter stars in the cluster has led to some reflection flaring around them. I find the effect quite pleasing, however.

The “Fox Fur Nebula” (Sharpless 273) can be seen below S Monocerotis in the above image. Its resemblance to road-kill is quite remarkable, even in this modest image. The bluish area arises from the reflection of starlight from dust in the region.  Some images show this reflection nebulosity to be much more extensive than seen here, probably because I did not compensate for the poorer blue sensitivity of the CCD with longer blue subs.

The Christmas Tree Cluster is visible to the naked eye in good conditions and appears quite striking in binoculars. The stars forming the Christmas tree shape, along with dozens of other tiny bright stars within the cluster, are a magical sight as seen in my VC200L with a 25mm eyepiece. None of the associated nebulosity is visible however, at least, not to me.

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