Sh2-82, The Little Cocoon Nebula

Sh2-82, The Little Cocoon NebulaClick image for full size version

July 26, 2014

My exploration of the faint members of the Sharpless catalogue, designated by “Sh2-,” continues with this image of Sh2-82.   This is part of my general goal to target fainter, more rarely imaged objects.   Sh2-82  lies in Sagitta, the Arrow, in a rich part of the Milky Way.  There is a dark lane of dust and soot running diagonally through the image, blocking out starlight behind it.   The nebula is made of two parts:  a red emission nebula surrounded by a “halo” of bluish reflection nebula.  The emission nebula is glowing red due to hydrogen in this star-forming region.  The reflection nebula is shining by reflected starlight, like a mirror.

I know I am getting into faint object territory when I can’t find much information about an object’s size, distance or age.   I did learn that Sh2-82 is an active star forming region, and has been the subject of recent publications in the journal “Research in Astronomy and Astrophysics.”  It is in our galaxy, and is probably on the order of thousands of light years away.

This object is sometimes referred to as the Little Cocoon Nebula, in reference to the much more famous Cocoon Nebula.


Acquisition, calibration and stacking in Maxim DL; image registration and all processing in PixInsight.  Acquired from my SkyShed in Guelph, ON.   SBIG STL-11000 with Baader HaLRGB filters.  10″ ASA @ f/6.8 on a Paramount MX.  Guiding with SV-80 80 mm f/6 refractor and cameras Remote Guide Head.  Imaging runs were scripted using CCDCommander.

11x10m R, 10x10m G, 10 x10m B, 20x20m Ha and 30x10m L (total – 16hr50m)

An RGB master file was made by combining the R, G and B channels.  The Ha, L and RGB files were cropped and background corrected with DBE.  Ha and RGB were combined with the NB-RGB script using an Ha multiplier of 1.2 and RGB bandwidth of 200.  The resulting HaRGB file was colour balanced and stretched with Histogram Transformation.  The L image was stretched with Histogram Transformation and ACDNR was applied, followed by a second stretch.  The RGB-luminance was extracted from the HaRGB file, matched to the Luminance master with linear fit and then combined back into the HaRGB image using ChannelCombine.  Then LRGBCombine was used to add the Luminance master to the HaRGB image.  The resulting HaLRGB image was tweaked with colour saturation and curves. Image scale is 1.1 arcsec/pixel.