  We present ellipsoidal light-curve fits to the quiescent B, V, R and I light
curves of GRO J1655-40 (Nova Scorpii 1994). The fits are based on a simple
model consisting of a Roche-lobe filling secondary and an accretion disc around
the black-hole primary. Unlike previous studies, no assumptions are made about
the interstellar extinction or the distance to the source; instead these are
determined self-consistently from the observed light curves. In order to obtain
tighter limits on the model parameters, we used the distance determination from
the kinematics of the radio jet as an additional constraint. We obtain a value
for the extinction that is lower than was assumed previously; this leads to
lower masses for both the black hole and the secondary star of 5.4 +/- 0.3 Msun
and 1.45 +/- 0.35 Msun, respectively. The errors in the determination of the
model parameters are dominated by systematic errors, in particular due to
uncertainties in the modeling of the disk structure and uncertainties in the
atmosphere model for the chemically anomalous secondary in the system. A lower
mass of the secondary naturally explains the transient nature of the system if
it is either in a late case A or early case B mass-transfer phase.
