  A nonlinear force-free solution is constructed for the coronal magnetic field
in NOAA solar active region AR 10953 based on a photospheric vector magnetogram
derived from Hinode satellite observations on 30 April 2007, taking into
account uncertainties in the boundary data and using improved methods for
merging multiple-instrument data. The solution demonstrates the
"self-consistency" procedure of Wheatland & Regnier (2009), for the first time
including uncertainties. The self-consistency procedure addresses the problem
that photospheric vector magnetogram data are inconsistent with the force-free
model, and in particular that the boundary conditions on vertical electric
current density are over-specified and permit the construction of two different
nonlinear force-free solutions. The procedure modifies the boundary conditions
on current density during a sequence of cycles until the two nonlinear
force-free solutions agree. It hence constructs an accurate single solution to
the force-free model, with boundary values close, but not matched exactly, to
the vector magnetogram data. The inclusion of uncertainties preserves the
boundary conditions more closely at points with smaller uncertainties. The
self-consistent solution obtained for active region AR 10953 is significantly
non-potential, with magnetic energy E/E_0 = 1.08, where E_0 is the energy of
the reference potential (current-free) magnetic field. The self-consistent
solution is shown to be robust against changes in the details of the
construction of the two force-free models at each cycle. This suggests that
reliable nonlinear force-free modeling of active regions is possible if
uncertainties in vector magnetogram boundary data are included.
