Sh2-88 Emission Nebula

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July 6, 2014; Photo of the Month, Bulletin of the Royal Astronomical Society of Canada, August 2014

The Sharpless catalogue, designated by “Sh2-” includes 313 emission nebulae visible from much of the northern hemisphere.  These nebulae glow red due to emissions from excited hydrogen atoms, which have absorbed energy from nearby stars and then re-emit it as red light.  All the Sh2 objects are in the Milky Way Galaxy, where the Sun and our solar system are located.  Sh2-88 is located about 5600 light years away in the constellation Vulpecula, the Little Fox, in a rich part of the Milky Way,  This is the reason for the huge number of stars in this image.  This nebula has been dubbed “the Face of God Nebula,” but it’s not clear to me why.

In addition to the main, diffuse nebula, Sh2-88A, there are two condensations of nebulosity at lower right, near the brightest star.  From top to bottom they are Sh2-88B1 and Sh2-88B2.  Each of these is lit by a star within the nebula.

Tekkies:

Acquisition in Maxim DL. All pre-processing and processing in PixInsight.  Acquired from my SkyShed in Guelph, ON.   SBIG STL-11000 with Baader HaRGB 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.

19x10m R, 20x10m G, 15 x10m B, 9x20m Ha and 8x30m Ha (total – 16hr)

The batch pre-processing script was used to calibrate, register and combine the Ha, R, G and B channels.  An RGB master file was made by combining the R, G and B channels.  The Ha and RGB files were cropped and background corrected with DBE.  RGB was colour balanced  and then Ha and RGB were combined with the NB-RGB script using an Ha multiplier of 4.  The resulting HaRGB file was colour balanced and stretched with Histogram Transformation.  ACDNR was applied, followed by a second stretch.  The file was tweaked with colour saturation and curves.  Image scale is 1.1 arcsec/pixel.