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We report moderate resolution 3-5 micron spectroscopy of the nucleus of NGC1068 obtained at 0.3 arcsec (20 pc) resolution with the spectrograph slitaligned approximately along the ionization cones of the AGN. The deconvolvedFWHM of the nuclear continuum source in this direction is 0.3 arcsec. Fourcoronal lines of widely different excitations were detected; the intensity ofeach peaks near radio knot C, approximately 0.3 arcsec north of the infraredcontinuum peak, where the radio jet changes direction. Together with thebroadened line profiles observed near that location, this suggests thatshock-ionization is the dominant excitation mechanism of the coronal lines. Thedepth of the 3.4 micron hydrocarbon absorption is maximum at and just south ofthe continuum peak, similar to the 10 micron silicate absorption. That and thesimilar and rapid variations of the optical depths of both features across thenucleus suggest that substantial portions of both arise in a dusty environmentjust in front of the continuum source(s). A new and tighter limit is set on thecolumn density of CO. Although clumpy models of the dust screen might explainthe shallowness of the silicate feature, the presence of the 3.4 micron featureand the absence of CO are strongly reminiscent of Galactic diffuse cloudenvironments and a consistent explanation for them and the observed silicatefeature is found if all three phenomena occur in such an environment, existingas close as 10 pc from the central engine.

The 3-5 micron Spectrum of NGC 1068 at High Angular Resolution: Distribution of Emission and Absorption Features across the Nuclear Continuum Source