DETECTION OF [OI] 63-MU-M IN ABSORPTION TOWARD SGR B2

A high signal-to-noise 52-90 mu m spectrum is presented for the centra l part of the Sagittarius B2 complex. The data were obtained with the Long Wavelength Spectrometer on board the Infrared Space Observatory ( ISO). The [O I] 63 mu m line is detected in absorption even at the gra ting spectral resolution of 0.29 mu m. A lower limit for the column de nsity of atomic oxygen of the order of 10(19) cm(-2) is derived. This implies that more than 40% of the interstellar oxygen must be in atomi c form along the line of sight toward the Sgr B2 molecular cloud.