The Cygnus Loop (also known as Sh2-103 or the radio source W78) is a large supernova remnant (SNR) in the constellation Cygnus, an emission nebula measuring nearly 3° across. Some arcs of the loop, known collectively as the Veil Nebula or Cirrus Nebula, emit in visible light. Radio, infrared and X-ray images reveal the complete loop. The visual portion of the Cygnus Loop is known as the Veil Nebula, also called the Cirrus Nebula or the Filamentary Nebula. Several components have separate names and identifiers, including the "Western Veil" or "Witch's Broom", the "Eastern Veil", and Pickering's Triangle. NGC 6960, the Western Veil, is the western part of the remnant, also known as the "Witch's Broom". NGC 6992, NGC 6995, and IC 1340 are three luminous areas, which make up the Eastern Veil. NGC 6992 is an HI shell located along the north-eastern edge of the loop. The identifier NGC 6979 is sometimes taken to refer to Pickering's Triangle (also known as Pickering's Wedge, or Pickering's Triangular Wisp), but the Triangle is probably not what the Catalogue intended for this entry. This is a segment of relatively faint nebulosity.