Observations of absorption by water vapor toward Sagittarius B2

We have observed the 1(10)-->1(01) pure rotational transitions of both (H2O )-O-16 and (H2O)-O-18 toward Sagittarius B2 using the Submillimeter Wave As tronomy Satellite. The spectra thereby obtained show a complex pattern of a bsorption and - in the case of (H2O)-O-16 - emission, with numerous feature s covering a wide range of LSR velocities (-130 to 130 km s(-1)) and repres enting absorption both in gas associated with Sgr B2 as well as by several components of foreground gas along the line of sight. The ortho-water abund ance derived for the absorbing foreground gas is similar to 6 x 10(-7) rela tive to H-2.