Magellan spectroscopy of low-redshift active galactic nuclei

We present an atlas of moderate-resolution (R 1200-1600) optical spectra of 94 low-redshift (z ≲ 0.5) active galactic nuclei taken with the Magellan 6.5 m Clay Telescope. The spectra mostly cover the rest-frame region ∼3600-6000Å. All the objects have pre-existing Hubble Space Telescope imaging, and they were chosen as part of an ongoing program to investigate the relationship between black hole mass and their host galaxy properties. A significant fraction of the sample has no previous quantitative spectroscopic measurements in the literature. We perform spectral decomposition of the spectra and present detailed fits and basic measurements of several commonly used broad and narrow emission lines, including [O II] λ3727, He II λ4686, Hβ, and [O III] λλ4959, 5007. Eight of the objects are narrow-line sources that were previously misclassified as broad-line (type 1) Seyfert galaxies; of these, five appear not to be accretion-powered.