The hard state of a transient black hole: is the accretion disk truncated?

The combination of the fast EPIC-pn modes and broad-band coverage with RXTE proved to be an effective means of exploring accretion in bright Galactic black holes. XMM and NuSTAR provide an even more powerful combination. We propose to make one joint 40~ks observation of a new or known black hole transient during a bright, hard outburst phase. The goals of this program are to 1) measure the spin of the black hole via the Fe K-alpha line and broad-band disk reflection spectrum, 2) test an apparent anti-correlation between winds and jets in soft and hard states by making a very sensitive search for winds in a hard, intermediate, or very high state. This observation will be supported by a network of ground-based observatories and X-ray monitoring.