  The Hubble Space Telescope has now observed four black hole X-ray transients
in outburst under an ongoing Target-of-Opportunity program: GRO J0422+32
(1994), GRO J1655-40 (1996), XTE J1859+226 (1999-2000) and XTE J1118+480
(2000). We summarise the highlights of this program to date, including a
diversity of spectral energy distributions, correlated X-ray/UV/optical rapid
variability and detailed UV spectroscopy.
