ISO-SWS spectroscopy of NGC 1068

We present Infrared Space Observatory-Short Wave Spectrometer (ISO-SWS) spe ctroscopy of NGC 1068 for the complete wavelength range 2.4-45 mu m at reso lving power similar to 1500. Selected subranges have been observed at highe r sensitivity and full resolving power similar to 2000. We detect a total o f 36 emission lines and derive upper limits for 13 additional transitions. Most of the observed transitions are fine-structure and recombination lines originating in the narrow-line region (NLR) and the inner part of the exte nded emission-line region. We compare the line profiles of optical lines and reddening-insensitive inf rared lines to constrain the dynamical structure and extinction properties of the NLR. The most likely explanation of the considerable differences fou nd is a combination of two effects: (1) The spatial structure of the NGC 10 68 NLR is a combination of a highly ionized outflow cone and lower excitati on extended emission. (2) Parts of the NLR, mainly in the receding part at velocities above systemic, are subject to extinction that is significantly suppressing optical emission from these clouds. Line asymmetries and net bl ueshifts remain, however, even for infrared fine-structure lines suffering very little obscuration. This may be either due to an intrinsic asymmetry o f the NLR, as perhaps also suggested by the asymmetric radio continuum emis sion or due to a very high column density obscuring component which is hidi ng part of the NLR even from infrared view. We present detections and limits for 11 rotational and rovibrational emissi on lines of molecular hydrogen (H-2). They arise in a dense molecular mediu m at temperatures of a few hundred kelvins that is most likely closely rela ted to the warm and dense components seen in the near-infrared H-2 rovibrat ional transitions, and in millimeter-wave tracers (CO, HCN) of molecular ga s. Any emission of the putative parsec-scale molecular torus is likely over whelmed by this larger scale emission. In companion papers we use the SWS data to derive the spectral energy distr ibution emitted by the active nucleus of NGC 1068, to put limits on infrare d emission from the obscured broad-line region, and discuss the continuum a nd its features in conjunction with SWS spectra of other galaxies.