The ISO-SWS 2.4-45.2 micron spectrum toward Orion IRc2

The complete infrared spectrum from 2.4 to 45.2 mu m toward the prototypica l massive star-forming region Orion IRc2 is presented, obtained with the Sh ort Wavelength Spectrometer (SWS) on board the Infrared Space Observatory ( ISO) at a resolving power lambda/Delta lambda approximate to 1300-2500. A w ealth of emission and absorption features is found, including H-2 vibration -rotation lines, the full set of H-2 pure rotational lines (0,0) S(1)-S(17) , H recombination Lines, ionic fine-structure lines, PAH emission features, and absorption and emission bands by interstellar ices and gas-phase molec ules, including CO2, CH4, and SO2. Particularly interesting is the detectio n of strong emission and absorption lines in the H2O nu(2) bending mode at 6.2 mu m and the observation of highly excited pure rotational Lines of H2O in absorption at 25-45 mu m. The origin of these lines in each of the phys ical components included in the ISO-SWS beam (H II region, PDR, quiescent r idge, shocked low-velocity plateau) is briefly discussed.