GX339-4 - A new black hole candidate

THE large area survey instrument on HEAO 1 has observed that the galactic X-ray source GX339–4 (4U1658–48) varies on time scales from tens of milliseconds to hundreds of days. Its long term variability was known from measurements made by OSO 71 and by Uhuru2 but this is the first observation of aperiodic variability on time scales of tens of milliseconds to a few seconds. We show here that the overall characteristics of GX339–4 place it in the same class of X-ray sources as Cyg X–1 (ref. 3 summarises Cyg X–1) and Cir X–12,4–6