G64.5+0.9, a new shell supernova remnant with unusual central emission
  We present observations between 1.4 and 18 GHz confirming that G64.5+0.9 is
new Galactic shell supernova remnant, using the Very Large Array and the
Arcminute Microkelvin Imager. The remnant is a shell ~8 arcmin in diameter with
a spectral index of alpha = 0.47 +/- 0.03 (with alpha defined such that flux
density S varies with frequency nu as S proportional to nu to the power of
-alpha). There is also emission near the centre of the shell, ~1 arcmin in
extent, with a spectral index of alpha = 0.81 +/- 0.02. We do not find any
evidence for spectral breaks for either source within our frequency range. The
nature of the central object is unclear and requires further investigation, but
we argue that is most unlikely to be extragalactic. It is difficult to avoid
the conclusion that it is associated with the shell, although its spectrum is
very unlike that of known pulsar wind nebulae.
