A cosmic gamma-ray burst on 1975 May 14

Abstract

1P cos: c gamma-ray burst reported that occurred at 29309 . 11 Q UTC, May S e 14, 1975. The burst was detected at an atmospheric depth of 4 g/ 2 residual atmosphere with the University of California double scatter gamma-ray telescope launched on a balloon from Palestine, Texas at 1150 UTC, May 13, 1975. The burst was observed both in the single scatter mode by the top liquid sciat.11ator tank in anti-coincidence with the surrounding plastic scintillator and in the double scatter mode from which energy and directional information are obtained. The burst is 24 standard deviations above the background for single scatter events. The total gammaray flux in the burst, incident on the At in with photon energy greater than 0.5 NeV, is 0.59, + 0 -0.15 !«,tons / a initial rise tine to 902 of maximumis O.J15 + 0.005 sand the duration is 0.11 s. Time structure d wn to the 5 as resolution of the tel ope is seen. The scan flux over this tine 5. _ 1,3 photons/ s cmand the anximsi flux is 8.5 + 2,1 photons j^t^-sA in energy S^ ci distribution is obtained from the single scatter flux and the 8 double Compton scattered gaga-rays recorded during the 0.11'x. When fittsd to a power law in energy II(>L) -A 8-0 , A -0.24 + 0.04 and a -1.3 + 0.2. The total energy in the burst above 0.5 '%V is 2 + 0 . 5 z 10 -6 erg/ cat . The direction of the source, with 902 confidence, is limited to a cirQle with radium of 250 and center at a R.A. of 2480 and a declination of +22 0 . In the search fat smaller bursts of more than 5o above be•kgrotod, 2 additioual candidates of 6.4 and 6.5vwere found. as. aumber of bursts, including candidate bursts is in agreement with the integral distribution S -1 ' S whete S is the total energy in the burst.

Early-time observations of gamma-ray burst error boxes with the Livermore optical transient imaging system

“…In the years which followed, several other spacecraft and balloon-borne detectors provided additional information about the characteristics of GRBs (e.g., Cline et al 1973;Herzo et al 1976;Cline et al 1979;Gilman et al 1980;Schtvartz et al 1987). The data were accompanied by numerous models attempting to explain the origin of GRBs (e.g., Grindlay 8i Fazio 1974;Hoyle & Clayton 1974;Woosley gL;Wallace 1982;Holcomb & Tajima 1991).…”

Double Scatter Telescope for Medium Energy Gamma Ray Astronomy from a Satellite

“…The energy spectrum above 1 MeV is measured along with any broadened lines present with a sensitivity of 2 x 10-6 ergs/cm2. This approach was successfully used with our balloon 13 telescope The DST event buffer and -primary microprocessor memories will be large enough to contain the double scatter events for most bursts. Active aperture control, utilizing the telescope's microprocessor, is employed.…”