  We present a study of the decays B+ -> rho+ gamma, B0 -> rho0 gamma, and B0
-> omega gamma. The analysis is based on data containing 347 million BBbar
events recorded with the BaBar detector at the PEP-II asymmetric B factory. We
measure the branching fractions BR(B+ -> rho+ gamma) = (1.10 +0.37/-0.33 +/-
0.09) x 10-6 and BR(B0 -> rho0 gamma) = (0.79 +0.22/-0.20 +/- 0.06) x 10-6, and
set a 90% C.L. upper limit BR(B0 -> omega gamma) < 0.78 x 10-6. We also measure
the isospin-averaged branching fraction BR(B->rho/omega gamma) = (1.25
+0.25/-0.24 +/- 0.09) x 10-6, from which we determine |Vtd/Vts| = 0.200
+0.021/-0.020 +/- 0.015, where the first uncertainty is experimental and the
second is theoretical.
