HARD X-RAY OBSERVATIONS OF THE LARGE MAGELLANIC CLOUD - UPPER LIMITS FOR FLUX OF SUPERNOVA-1987A

Observations of the Large Magellanic Cloud by the Granat observatory S igma telescope have detected no statistically significant flux in the hard x-ray range from any of the 97 sources observed with the Einstein observatory (Long et al., 1981) in the 0.15-4.5 keV soft x-ray range (with the possible exception of the source CAL 87). The sensitivity ac hieved in the observations at the 3sigma level corresponded to 6 . 10( 37) erg/sec in the energy range 40-150 keV (assuming a Magellanic clou d distance of 55 kpc). Such brightness would correspond to a source se veral times brighter than the well known galactic black hole candidate Cyg X-1. We present upper limits for the flux from the most interesti ng sources in the Large Magellanic Cloud, including LMC X-1 and LMC X- 4. According to the measurements, the quantity of radioactive elements in the remnant SN 1987A was limited to 2.4 . 10(-3) M. for Na-22 and 2.3 . 10(-2) M. for Ti-44.