High-energy x-ray spectra of five sources

On 1970 October 15-16, we carried out balloon X-ray observations from Australia ai energies above 15 keV. We present the high-energy X-ray spectra of three sources discovered by us, GX 301-2, GX304-1, and GX1 +4. The data suggest that these high-energy sources correspond to the sources 2U 1223-62, 2U 1258-61, and 21J 1728-24 respectively. We also present the spectra for two additional sources, GX 5-1 (2U 1757-25) and GX 3+ 1 (2U 1TW-26). The average intensity of the highly variable source GX 301-2 was observed to be as great as Tau X-1 in the energy range 15-50 keV. (auth)