Cygnus Loop/ Veil Nebula Complex

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The 'Cygnus Loop' or Veil Nebula complex is a large shell of expanding gas in the constellation Cygnus the Swan that is the remains of a supernova explosion estimated to have occurred 10,000-20,000 years ago. Some of the latest research (Reference 1) indicates that this large supernova remnant lies some 735 pc (2396 light years) from our solar system. The complete remnant is quite large (3° 15' x 2° 35' shown here), and its various sections have their own catalogue designations. The bright arc at lower left is often referred to as the Western Veil Nebula or Witches Broom, and carries the designation NGC 6960. At bottom center is a beautiful filamentary region known as 'Pickering's Triangle.' At far right is the Eastern Veil, or NGC 6992 and NGC 6995. Although many searches for the stellar remnant of the supernova explosion have been conducted, no definitive object has been found.

  Optics:Stellarvue SVQ-100 
Camera:Starlight Xpress SX-46  
Exposure info:20 minute subs / 24 hours total across 2-frame mosaic 
Filters used:Astrodon H-alpha, OIII 
date:August & September 2020 
color mapping:Halpha = Red / O3 = Green, Blue 

The image above is a two-frame mosaic, taken through narrowband filters--filters that allow only a thin band of light at very specific wavelengths to pass through to the digital camera. Two filters were used in the above image: H-alpha (hydrogen, 656 nm) and OIII (doubly ionized oxygen, 500 nm). The resulting image from each filter is then assigned a color channel to make the final, color image. While the color pallete is somewhat arbitrary, chosen for aesthetic reasons--the colors here are a reasonable estimate of what the human eye would see. Shown below are the individual image stacks through each filter that were used for the final image.

Below is an extended version of the image above (rotated 180 degrees), to encompass additional area and some of the extended nebulosity of the supernova remnant (4-frame mosaic).

H-alpha filterOIII filter

A new process available in Pixinsight allows for the automatic removal of stars from an image, and the possibility of creating an interesting view of nebula such as this where some of the fainter regions of nebulosity are more prominent:

The constellation Cygnus the Swan is located along the belt of the Milky Way, making it densly populated with stars and gaseous nebula. The annotated image at left is a wide-field view of the constellation taken through a narrow-band H-alpha filter (Canon 6D and 50mm lens). The named stars and various NGC and IC objects are labeled, and the small white square at upper left outlines the approximate area of the Cygnus Loop / Veil Nebula shown in the image above. (click on the image for a larger pop-up version.)

Cygnus is one of the largest and most recognizable constellations in the northern sky in summer and fall, with its five brightest stars (Deneb, Sadr, Gienah, Al Fawaris and Albireo) forming a distinctive "cross," and the constellation is sometimes referred to as the Northern Cross. Deneb is a blue-white supergiant of magnitude +1.33 and easily the brightest star in Cygnus. As can be seen in the H-alpha image at left, the entire constellation is brimming with clouds of ionized hydrogen gas. In addition to the Cygnus Loop, the constellation contains several well-known nebula such as the North American Nebula (upper right), the Crescent Nebula and the Gamma Cygni Nebula (center).

There are apparently quite a few myths associated with the constellation....quoting from Reference 2 "Cygnus the Swan is supposed to be Zeus (Jupiter), king of the gods, in disguise. Zeus assumed this form when visting one of his many lady loves, Leda, Queen of Sparta. The result of the liaison was an egg, out of which hatched the twins Castor and Pollux and also Helen, who would become the beautiful Helen of Troy, with the 'face that launched a thousand ships.' Pollux and Helen were both Zeus' children, but Castor was not; he was the son of the King of Sparta."


1. Fesen, Weil and Cisneros, "The Cygnus Loop's Distance, Properties and Envrionment Driven Morphology." Monthly Notices of the Royal Astronomical Society, January 23, 2015

2. Kerrod, Robin "The Star Guide: How to Read the Night Sky Star by Star." New York: MacMillan, 1993