Gamma-ray burst measurements with A 6.3 m² array

Abstract

Two flights from Alice Springs, Australia, were achieved in November 1977 and November 1978 with a plastic scintillator γ-burst detector, effective area 6.3 m², thickness 5 cm, energy response in the range 50 keV to 2 MeV. In 33 hr of good, high altitude data, two bursts were detected, yielding a rate corrected to an isotropic flux of$7.03 \times 10^3 {\text{y}}^{ - 1} \left\{ {\begin{array}{*{20}c} { + 10 \times 10^3 } \\ { - 6 \times 10^3 } \\ \end{array} } \right\}$ at a size of 8.5×10⁻⁹ erg cm⁻². One event, seen at 22.14 on 15 Nov 1978, was confirmed by spacecraft measurements. The second, too small to be detected by spacecraft, arrived from 0 hr RA, −13.2° Decl. ±12° and possibly comes from a confirmed γ-burst source location. A galactic origin with a source distribution originating from a relatively thick disk, is favoured by these results.