A mosaic of three images taken thru an h-alpha filter with an STL-1301E CCD camera thru Kopernik's 20-inch F/8.1 Ritchey Chretien Cassegrain telescope focal reduced to F/5.
NGC6992, in the Constellation of Cygnus, makes up the eastern loop of the Veil Nebula.
It is a part of a supernova remnant that is the shattered remains of one, and possibly two, supernovae that exploded more than 15,000 years ago at a distance of 2,500 light-years from Earth in the direction of the constellation of Cygnus, the Swan. At the time of the explosion, it would have been seen as a very bright star, rivaling the crescent Moon.
Parts of the nebula appear to be rope-like filaments. This is because the shock waves expanding from the supernova explosion are so thin that the shell is visible only when viewed exactly edge-on, giving the shell the appearance of filaments. Undulations in the surface of the shell lead to multiple filamentary images, which appear to be intertwined.
Even though the nebula is relatively bright, it is spread over so large an area that the surface brightness is quite low, so the nebula is notorious among astronomers as being difficult to see visually. However, an observer can see the nebula clearly in a telescope using an OIII filter (a filter isolating the wavelength of light from doubly ionized oxygen). Kopernik Observatory's telescopes, when equipped with an OIII filter, show the delicate lacework apparent in image above.
George Normandin, KAS
September 25th, 2011