THE BROAD-BAND X-RAY-SPECTRUM OF SN-1978K AND 2 OTHER LUMINOUS X-RAY SOURCES IN THE SPIRAL GALAXY NGC-1313

We present preliminary results of our analysis of the ASCA PV phase ob servation of the nearby spiral galaxy NGC 1313. ASCA cleanly resolves the three previously known luminous sources, one of which is the very luminous supernova, SN 1978k. The spectrum of SN 1978k is described by either a power law with a photon index GAMMA approximately 2.2 or a t hermal model with temperature kT approximately 3.0 keV and abundances Z approximately 0.2 Z.. There is no evidence for strong line emission from it or from the other two sources. The spectrum of SN 1978k arises either in shocked gas in extreme departure from ionization equilibriu m or from synchrotron processes associated with a newborn pulsar. A se cond source, near the galactic center, is well-fit by a power-law with a photon index of approximately 1.8. It is possibly an active nucleus -like source, but physically displaced from the optical nucleus of the galaxy. The spectrum of the third source, located 8 kpc south of the nucleus, along with the absence of an optical counterpart, suggests th at it is a low-mass X-ray binary; but its high X-ray luminosity clouds this interpretation. This observation demonstrates the ability of ASC A to perform effective broad band spectroscopic measurements of source s at a 2-10 keV flux level of 5 X 10(-13) erg cm-2 s-1.