Gamma-ray Burst 79-03-05

D. Evans, R. Kiebesadel and J. Baros, Los Alamos Scientific Laboratory; and T. Cline, U. Desai, B. Teegarden and G. Pizzichini, Goddard Space Flight Center, report that data from gamma-ray-burst instruments on the Pioneer Venus Orbiter and the Helios-B and ISEE-3 satellites have been used to establish an error box for the source of an event that occurred on ~ Mar. 5d15h52m05s UT. Confirmation of the event has been provided by K. Hurley, M. Niel and G. Vedrenne, Centre d'Etude Spatiale de Rayonnements; I. V. Estulin, Space Research Institute; and E. P. Mazets, Physical-Technical Institute, based on data from Venera 11 and 12 and by data from the Vela 5A, SB and 6A satellites. The Mar. 5 event was different from a typical gamma-ray burst in several respects: it was more intense by at least an order of magnitude; the risetime was much shorter, with the observed count rate increasing from background to near maximum in < 0.25 ms; the spectrum was significantly softer; the decay time was < 100 ms. The error box is ~ 1'.0 by 1'.5 centered at R.A. = 5h25m.92, Decl. = -66o07'.3 (equinox 1950.0). Included in the error box is a portion of N49, a supernova remnant in the Large Magellanic Cloud described by Mathewson and Clark (1973, Astrophys. J. 179, 89), who suggested that the nearby radio source may have been ejected from the remnant. N49 and 0525-66.0 have recently been observed by HEAO 2 and reported by Helfand (1979, Bull. Am. Phys. Soc. 24, No. 4) as very luminous soft x-ray sources. If N49 were the source of the gamma-ray burst, then the peak luminosity in gamma-rays was ~ 10**44 erg/s and the total energy radiated was ~ 10**43 erg.