Cygnus Loop: A double bubble?
  The Cygnus Loop is a well-studied supernova remnant (SNR) that has been observed across the electromagnetic spectrum. Although widely believed to be an SNR shell with a blow- out region in the south, we consider the possibility that this object is two SNRs projected along the same line-of-sight by using multi-wavelength images and modelling. Our results show that a model of two objects including some overlap region/interaction between the two objects has the best match to the observed data. 
J. West, S. Safi-Harb, I. Reichardt, J. Stil, R. Kothes, T. Jaffe, and   GALFACTS team
astro-ph.GA astro-ph.HE