X-ray line emission from the Cygnus Loop

The HEAO 1 satellite has observed the X-ray spectrum of the Cygnus Loop in the 0.1-2.0 keV band. The observed count-rate spectrum is deconvolved by the Kahn and Blissett technique to demonstrate conclusively the presence of oxygen- and iron-line emission between 0.6 and 0.9 keV. The spectrum has been fitted with single- and two-component Raymond-Smith plasma emission models. The best-fit dominant X-ray temperature is approximately 3,200,000 K, and the best-fit interstellar column density is approximately a few times 10 to the 20th/sq cm.