HI emission from quasar host galaxies.

A sensitive search for H I emission from the host galaxies of all seven "real" quasars (M_B < -21.5 for H₀ = 100 km s^-1Mpc^-1) with z < 0.1 lying in the declination range +2 < δ(deg) < +35 was made with the new λ = 22 cm feed at Arecibo. Both I Zw 1 and Mrk 304 reside in galaxies containing 7×10⁹M_sun; of neutral hydrogen. About 12×10⁹M_sun; of H I was detected in the Ton 951 field. The remaining quasar host galaxies were not detected at levels ⪆10⁹M_sun;. An extremely accurate systemic velocity was obtained from the apparently undisturbed symmetric horned profile of I Zw 1. It shows that the low-ionization emission-line system is nearly at rest, while the high-ionization forbidden lines [O III] and [Ne III] are blueshifted by 700 km s^-1 relative to the systemic frame. This blueshift appears to require both radial motions and dust absorption in the high-ionization portion of the narrow-line emitting region.