[ITAL]Chandra[/ITAL] Observations of SN 1999[CLC]gi[/CLC] and the X-Ray Emission of Type II-P Supernovae

We report on the probable X-ray detection, using the Chandra X-Ray Observatory, of the Type II-plateau (II-P) supernova SN 1999gi in the spiral galaxy NGC 3184. A faint source is located within 04 of the supernova's optical position. The inferred luminosity is ~1 × 1037 ergs s-1 in the 0.5-10 keV band for an adopted 1 keV thermal bremsstrahlung spectrum. The luminosity from SN 1999gi is very similar to that inferred from the Chandra detection of the Type II-P SN 1999em in NGC 1637 for which we extracted data from the Chandra archive. We suggest that Type II-P supernovae show X-rays initially at outburst, subsequently fade, and are not significant X-ray emitters prior to the remnant stage.