THE X-RAY LIGHTCURVE OF SN-1987-A

X-ray observations of SN 1987A in the Magellanic Clouds have been perf ormed throughout tile ROSAT mission, using the PSPC and the HRI detect ors. We present the X-ray light curve based on all observations in the years 1991-1995. For the first time a significant increase of the X-r ay flux from SN 1987A can be seen, corresponding to X-ray luminosities (0.5-2 keV) of 0.8 - 2.2 x 10(34) erg/s about 4 - 8 years after the e xplosion. SN 1987A is surrounded by a ringlike nebula, which is though t to form the interface between the blue-supergiant wind and the dense r red-supergiant wind of the progenitor. The X-ray data can constrain the density of the matter inside the ring to about 30 amu cm(-3) and t he date at which the blast wave will reach the ring to about AD 2003, when a dramatic brightening is expected to occur. Nevertheless, other interpretations of the X-ray emission are possible.