Faculty of Science (FNWI) - Anton Pannekoek Institute for Astronomy (API)
Abstract
Since September 2007 we have been monitoring the optical counterpart (V, R and i-bands) of the black hole X-ray binary GX 339-4 with the Faulkes Telescope South situated at Siding Spring in Australia. The source has continued to decline from its 2006-7 outburst (ATel #968) until May 2008, in which a period of strong variability began. At its faintest flux level, on 2008-04-29 (MJD 54585.51) the magnitudes were V = 18.39 +- 0.06; R = 18.10 +- 0.03; i = 17.22 +- 0.03.