THE ALFALFA "ALMOST DARKS" CAMPAIGN: PILOT VLA H I OBSERVATIONS OF FIVE HIGH MASS-TO-LIGHT RATIO SYSTEMS

We present new Very Large Array (VLA) H I spectral line imaging of five sources discovered by the ALFALFA extragalactic survey. Roughly 75% of the 200 objects without identified counterparts in the alpha .40 database (Haynes et al. 2011) fall into category 1 (likely tidal), and were not considered for synthesis follow-up observations. The pilot sample presented here (AGC193953, AGC208602, AGC208399, AGC226178, and AGC233638) contains the first five sources observed as part of a larger effort to characterize H I sources with no readily identifiable optical counterpart at single dish resolution (3'.5). Four of the sources with uncertain or no optical counterpart in the ALFALFA data are identified with low surface brightness optical counterparts in Sloan Digital Sky Survey imaging when compared with VLA H I intensity maps, and appear to be galaxies with clear signs of ordered rotation in the H I velocity fields.