SN 1988Z is the most luminous X-ray-emitting supernova , initially detected in 1995 using the ROSAT HRI with a luminosity of \sim 8 \times 10 ^ { 40 } erg s ^ { -1 } ( 12 ) .
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 SN 1988Z using the ACIS detector on Chandra .
We readily detect SN 1988Z , obtaining \sim 30 net counts which corresponds to a 0.2-2.0 keV luminosity of \sim 3.2 \times 10 ^ { 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 \pm 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 \sim 5,000 years before the explosion .
If the circumstellar medium is due to progenitor mass loss , then the mass loss rate is extremely high ( \sim 10 ^ { -3 } M _ { \sun } yr ^ { -1 } ( v _ { w } /10 km s ^ { -1 } ) ) .
The X-ray results are compared with the predictions of models of SN1988Z .