THE Z=0.8596 DAMPED LY-ALPHA ABSORBING GALAXY TOWARD PKS-0454+039

We present Hubble Space Telescope and ground-based data on the z(abs) = 0.8596 metal-line absorption system along the line of sight to PKS 0 454+0356. The system is a moderate-redshift damped Ly alpha system, wi th N(H I)=(5.7 +/- 0.3) x 10(20) cm(-2) as measured from the faint Obj ect Spectrograph spectrum. We also present ground-based images which w e use to identify the galaxy which most probably gives rise to the dam ped system; the most likely candidate is relatively underluminous by Q SO absorber standards (M(B) similar to -19.0 for q(0) = 0.5 and H-0 = 50 km s(-1) Mpc(-1)) and lies similar to 8.5 h(-1) kpc in projection f rom the QSO sight line. Ground-based measurements of Zn II, Cr II, and Fe II absorption lines from this system allow us to infer abundances of [Zn/H] = -1.1, [Cr/H] = -1.2, and [Fe/H] = -1.2, indicating overall metallicity similar to damped systems at z > 2, and that the depletio n of Cr and Fe onto dust grains may be even less important than in man y of the high-redshift systems of comparable metallicity. Limits previ ously placed on the 21 cm optical depth in the z = 0.8596 system, toge ther with our new N(H I) measurement, suggest a very high spin tempera ture for the H I, T-S> 580 K.