FAINT OBJECT CAMERA OBSERVATIONS OF COMPLEX NUCLEAR-STRUCTURE IN PKS-2158-380

We present the results of Hubble Space Telescope observations of the n ucleus of the narrow-line radio galaxy PKS 2158-380. Faint Object Came ra images (taken before the December 1993 servicing mission) in bands centered near 3720 Angstrom and 3420 Angstrom show complex nuclear str ucture. The nucleus consists of three well resolved components of size s similar to 0.3 '' (similar to 0.28 kpc, assuming H-0=50 km s(-1) Mpc (-1)), strung over similar to 1.5 '' (similar to 1.4 kpc), exhibiting emission line gas. The components lie within similar to 1 '' (similar to 0.97 kpc) of the centre of the galaxy as derived from the stellar d istribution, but none lies at the very centre. There is no evidence fo r a central unresolved point source at the galactic nucleus. UV band i mages taken near 1400 Angstrom also show some of this nuclear structur e, but very weakly. There is no evidence for a nuclear UV continuum po int source, contrary to suggestions made based on ground based data. T he data are discussed in relation to the large-scale properties of the emission line gas and radio structure of PKS 2158-380.