  SN1988Z is the most luminous X-ray-emitting supernova, initially detected in
1995 using the ROSAT HRI with a luminosity of ~8x10^40 erg s^-1 (Fabian &
Terlevich 1996). Its high luminosity was ascribed to expansion of the blast
wave into an especially dense circumstellar medium. In this paper, we describe
a recent observation of SN1988Z using the ACIS detector on Chandra. We readily
detect SN1988Z, obtaining ~30 net counts which corresponds to a 0.2-2 keV
luminosity of ~3.2x10^39 erg s^-1. The calculated quantiles for the extracted
counts allow a broad range of temperatures, but require a temperature hotter
than 5 keV if there is no intrinsic absorption. The long term light curve
(1995-2005) declines as t^-2.6+/-0.6. This is one of the steepest X-ray light
curves. The X-ray luminosity indicates that the emitting region has a high
density (>10^5 cm^-3) and that the density profile is not consistent with a
constant mass loss stellar wind during the ~5000 years before the explosion. If
the circumstellar medium is due to progenitor mass loss, then the mass loss
rate is extremely high (~10^-3 M_sol yr^-1(v_w / 10 km s^-1)). The X-ray
results are compared with the predictions of models of SN1988Z.
