  We present preliminary results of a search for the decays B+ -> rho+ gamma,
B0 -> rho0 gamma, and B0 -> omega gamma. The analysis is based on data
containing 347 million BB events recorded with the BaBar detector at the PEP-II
B factory. We measure branching fractions of BF(B+ -> rho+ gamma) =
(1.06^{+0.35}_{-0.31} +- 0.09) x 10^{-6} and BF(B+ -> rho0 gamma) =
(0.77^{+0.21}_{-0.19} +- 0.07) x 10^{-6}, where the first errors are
statistical and the second systematic, and set a 90% C.L. upper limit of BF(B0
-> omega gamma) < 0.84 10^{-6}. Assuming isospin relations between the three
branching fractions, these results are used to determine the CKM matrix element
ratio |V_td/V_ts| = 0.171^{+0.018}_{-0.021}(exp.)^{+0.017}_{-0.014}(theor.).
