  Three magnetic-field induced heteronuclear Feshbach resonances were
identified in collisions between bosonic 87Rb and fermionic 40K atoms in their
absolute ground states. Strong inelastic loss from an optically trapped mixture
was observed at the resonance positions of 492, 512, and 543 +/- 2 G. The
magnetic-field locations of these resonances place a tight constraint on the
triplet and singlet cross-species scattering lengths, yielding -281 +/- 15 Bohr
and -54 +/- 12 Bohr, respectively. The width of the loss feature at 543 G is
3.7 +/- 1.5 G wide; this broad Feshbach resonance should enable experimental
control of the interspecies interactions.
