Hα3: An Hα imaging survey of HI selected galaxies from ALFALFA: V. The Coma supercluster survey completion

Neutral hydrogen represents the major observable baryonic constituent of galaxies that fuels the formation of stars through transformation of molecular hydrogen. The emission of the hydrogen recombination line Hα is the most direct tracer of the process that transforms gas (fuel) into stars. We continue to present Hα3 (acronym for Hα - αα), an extensive Hα+[NII] narrow-band imaging campaign of galaxies selected from the HI Arecibo Legacy Fast ALFA Survey (ALFALFA), using the instrumentation available at the San Pedro Martir (SPM) observatory (Mexico). In 48 nights since 2011 we were able to carry out the Hα imaging observations of 724 galaxies in the region of the Coma supercluster 10h < RA < 16h; 24° < Dec < 28° and 3900 < cz < 9000 km s-1. Of these, 603 are selected from the ALFALFA and constitute a 97% complete sample. They provide for the first time a complete census of the massive star formation properties of local gas-rich galaxies belonging to different environments (cluster vs. filaments), morphological types (spirals vs. dwarf Irr), over a wide range of stellar mass (∼ 108 - 1011.5 M⊙) in the Coma supercluster. The present Paper V provides Hα data and derived star formation rates for the observed galaxies.