21 Centimeter H [CSC]i[/CSC] Line Observations of the Cygnus Loop

Twenty-one centimeter neutral hydrogen line observations of the Cygnus Loop have been made with the Dominion Radio Astrophysical Observatory's Synthesis and 26 m telescopes. Spectral line maps in 128 channels with 1.65 km s -1 velocity separation were constructed for a 6° square field encompassing the Cygnus Loop. A number of H I features are detected in and around the Cygnus Loop. Several features are found that are adjacent either to the outer rim or to filaments, which are most likely on the front or back face of the Cygnus Loop. Additionally, there is a clear deficit of H I for the interior of the Cygnus Loop compared to the immediate surroundings. The velocities and spatial structure of the deficit are interpreted as being due to a supernova remnant located between two blister regions: the main body of the Cygnus Loop is on the near side of a blister region, and the southern extension is on the far side of a second blister region.