  The recurrent nova IM Nor was observed twice in X-rays with Chandra ACIS-S, 1
and 6 months after the optical outburst. It was not detected in the first
observation, with an upper limit on the X-ray luminosity in the 0.2-10 keV
range L(x) < 4.8 x 10^(30) x (d/1 kpc)^2 erg s^(-1) (where d is the distance to
the nova). Five months later, a hard X-ray source with L(x) = (1.4-2.5) x
10^(32) x (d/1 kpc)^2 erg s^(-1) was detected. The X-ray spectrum appears to be
thermal, but we cannot rule out additional components due to unresolved
emission lines. A blackbody component is likely to contribute to the observed
spectrum, but it has bolometric luminosity L$_{\rm bol} = 2.5 x 10^(33) x (d/1
kpc)^2 erg s^(-1), therefore it is not sufficiently luminous to be due to a
central white dwarf which is still burning hydrogen on the surface. An optical
spectrum, taken 5 months post-outburst, indicates no intrinsic reddening of the
ejecta. Therefore, we conclude that the shell had already become optically thin
to supersoft X-rays, but nuclear burning had already turned off, or was in the
process of turning off at this time. We discuss why this implies that recurrent
novae, even the rare ones with long optical decays like IM Nor, indicating a
large envelope mass, are not statistically significant as type Ia SN
candidates.
