Decimeter maps and radio spectra of S147 and the Cygnus Loop

Radio maps of S147, at 0.2 and 0.4 0Hz, are presented. Consistent choices of baselines and integration boundaries for these maps yield a spectral index of -0.67i0.37 for this remnant, steeper than previously determined. A new 0.6-0Hz map of the Cygnus Loop is presented, and the currently popular idea that this remnant radiates by compression of the interstellar medium is critically discussed. Finally, the frequency at which a steepening of the radio spectrum will occur for such an emission mechanism is derived in the Appendix.