Hard X-ray observation of GX339−4 with welcome-1

The black hole candidate GX339−4 and the Galactic Center region were observed simultaneously in the hard X‐ray region with the balloon‐borne telescope, Welcome‐1. The obtained energy spectrum of GX339−4 is harder than that of the Galactic Center and is consistent with a single power‐law function of photon index α=1.52±0.34 in the energy range 60–600 keV.