X-RAY EVIDENCE FOR THE ASSOCIATION OF G11.2-0.3 WITH THE SUPERNOVA OF 386-AD

We present ROSAT observations of the radio-bright supernova remnant G11.2-0.3 which support the hypothesis that it is the remnant of the historical supernova SN 386 AD. The PSPC data imply a post-shock temperature of kT = 2.4 (+2.3, - 1.0) keV (95 per cent confidence limits), equivalent to a shock speed of 1400 km s-1, and an absorbing column density N(H) = 1.3 (+0.4, -0.2) x 10(22) cm-2, for a homogeneous, equilibrium plasma model. For an assumed age of 1607 yr, these data imply a distance of 9 kpc and a peak apparent magnitude of about 2 mag, consistent with a Type Ia supernova.