Quoted from SEDs:
Discovered on September 5, 1784 by William Herschel.
The image in this page was obtained by (and is courtesy of) Brad Wallis and Robert Provin, exposed 1 hour and 45 minutes on hypered 4x5 inch Kodak Tech Pan, on their 152mm f/7.5 Astro-Physics EDF refractor.
This object is so large (six times the diameter of the Full Moon) that to earlier observers its brighter parts appeared as a number of distinct diffuse nebulae, and were assigned e.g. separate NGC numbers, NGC 6960, NGC 6979, NGC 6992, and NGC 6995; fainter extensions have additional catalog identities: An extension of Northern part NGC 6979 got the designation NGC 6974, and an extension of southwestern NGC 6995 was cataloged as IC 1340. Already William Herschel had them as separate objects: H 2.206 = NGC 6979, H 5.14 = NGC 6992/95, H 5.15 = NGC 6960. The portions of the nebula have also been given a number of nicknames: NGC 6960 was called Filamentary Nebula or Lace-work Nebula, the brightest part of NGC 6979 has got the nickname Pickering's Triangle or Fleming's Triangle, and the complex of NGC 6992 and NGC 6995 is named Network nebula. In above image, they are situated as follows:
- NGC 6960 is the bright narrow nebula in the central to lower right; the bright star seen close to its middle is 52 Cygni. This nebula is also nicknamed Filamentary Nebula or Lace-work Nebula.
- NGC 6979 is the fainter triangular nebulosity in upper right; this is Pickering's of Fleming's Triangle.
- The faint extension to upper left of NGC 6979 is NGC 6974. This one was separately cataloged by Lawrance Parsons in 1873.
- NGC 6992 is the upper part of the bright nebula in the left.
- NGC 6995 is the lower part of that bright nebula. Both NGC 6992 and 6995 are named the Network Nebula. It was John Herschel who assigned it two different numbers in 1825.
- The faint lower extension to that nebula is IC 1340. This one was cataloged by Safford in 1866.
Despite its overall brightness of about mag 5, this object is only visible to the naked eye under exceptionally good viewing conditions, because its light is distributed over the object's large size.
- Cygnus Loop (G74.0-8.5) data from D.A. Green's Catalogue of Galactic Supernova Remnants
- Bill Arnett's Veil Nebula page
- NGC and IC entries from NGC Online: NGC 6960, NGC 6974, NGC 6979, NGC 6992, NGC 6995, IC 1340