This is the supernova remnant in Cygnus known as the Veil Nebula, here in its entirety, from the eastern arc at left, catalogued as NGC 6992/5, to the western arc at right, NGC 6960, running past the star 52 Cygni. At top is the wedge-shaped "Pickering's Triangle.," but discovered photographically by Wiliamina Fleming, one of the Harvard "computers." The field is filled with lots of little nebula bits and shrapnel-like fragments. All are remains of a star that exploded as a supernova some 10,000 to 20,000 years ago and is about 2,400 light years away. The red is emission from ionized hydrogen, the cyan emission from ionized oxygen. This nebula shows a lot of oxygen emission at the leading edge of the expanding cloud of debris. This is a blend of three stacks of exposures: -- 10 x 8 minutes at ISO 3200 through an Optolong L-eXtreme very narrowband filter which lets through just green-blue oxygen III and red hydrogen alpha wavelengths -- 8 x 8 minutes at ISO 1600 through an Optolong L-eNhance narrowband filter which lets through a broader bandwidth of light at those two main wavelenths, OIII and Ha -- 8 x 6 minutes at ISO 800 through no filter which records the full spectrum of light All were with the Canon EOS Ra through the SharpStar 94mm apo refractor at f/4.4 with its reducer/flattener and using an AstroHutech filter drawer between the flattener and camera to aid filter swapping. The L-eNhance set was taken June 11 until clouds intervened; the other 2 sets were taken the next night June 12. There was only about 2 hours of semi-darkness at this time of year from my latitude of 51° N. Guiding was with the MGEN3 stand-alone auto-guider (which applied a 5-pixel dither or image shift between each exposure) and William Optics 30mm guidescope. So impressive results less than 2 weeks from solstice at my latitude, made possible by the filters. With the dithering, no LENR or darks were applied, despite this being a warm-ish night. The L-eXtreme set contributes the cyan component; the L-eNhance set contributes the red component best; the clear base layer contributes more normally coloured stars, as the filters tend to discolour the stars and add haloes. All stacking, aligning, blending and masking were with Photoshop, with luminosity masks created with Lumenzia for selected adjustments to regions of different brightnesses. A high pass sharpen also added to the bright areas with another luminosity mask.
This is the roughly 10°-wide area area in Vela containing the fragmentary Vela Supernova Remnant (semicircular magenta-cyan arcs of nebulosity at lower area of field,) the Pencil Nebula (aka Herschel's Ray, or NGC 2736) at left of centre, and the large HII regions: Gum 17, 15 and 14 (left to right, with Gum 17 the most obvious just right of centre and above). Two brightest patches at lover left at Gum 25 (left) and RCW38 (right). The bright star at upper left is Suhail, Lambda Velorum. This is a stack of 9 x 2 minute exposures at f/2.8 with 135mm Canon L-series lens and filter-modified Canon 5D MkII at ISO 1250. Some light haze came over at the end of the sequence. Taken from Atacama Lodge, Chile, May 2011.
