Observation project of cosmic gamma-ray burst

Since the discovery of cosmic gamma-ray bursts by the Vela satellites, gamma-ray bursts of more than thirty have been detected by several satellites. Because the celestial bodies corresponding to the burst sources have not been found, the origin and the emission mechanism of gamma-ray bursts have been totally unknown. To measure the accurate position of gamma-ray bursts, the orthogonal rotational modulation collimator system is proposed. The burst position can be determined for the burst size of 5 x 10-5 erg/cm2. The detection system consists of two 5 in dia NaI(Tl) scintillators and one 4 in dia. NaI(Tl) scintillator. Two 5 in dia. NaI(Tl) are used for the orthogonal, rotational modulation collimator system, and one 4 in dia. NaI(Tl) is used as the monitor counter. The rotation speed of modulation collimators is 3 rpm, and X-ray between 20 and 200 keV can be detected with this detection system. The balloon launching of the system is scheduled in Sept. 1975. (J.P.N.)