The BIMA Survey of Nearby Galaxies (BIMA SONG). II. The CO Data

The BIMA Survey of Nearby Galaxies is a systematic imaging study of the 3 mmCO J = 1--0 molecular emission within the centers and disks of 44 nearby spiralgalaxies. The typical spatial resolution of the survey is 6", or 360 pc at theaverage distance (12 Mpc) of the sample, over a field of view of 10kpc. Thevelocity resolution of the CO observations is 4 km/s. The sample was not chosenbased on CO or infrared brightness; instead, all spirals were included that metthe selection criteria of vsun <= 2000 km/s, dec >= -20deg, inc <= 70deg, D25 <70', and BT < 11.0. The detection rate was 41/44 sources or 93%. Fully-sampledsingle-dish CO data were incorporated into the maps for 24 galaxies; thesesingle-dish data comprise the most extensive collection of fully-sampled,two-dimensional single-dish CO maps of external galaxies to date. We alsotabulate direct measurements of the global CO flux densities for these 24sources. We demonstrate that the measured ratios of flux density recovered area function of the signal-to-noise of the interferometric data. We examine thedegree of central peakedness of the molecular surface density distributions andshow that the distributions exhibit their brightest CO emission within thecentral 6" in only 20/44 or 45% of the sample. We show that all three LocalGroup spiral galaxies have CO morphologies that are represented in SONG, thoughthe Milky Way CO luminosity is somewhat below the SONG average, and M31 and M33are well below average. This survey provides a unique public database ofintegrated intensity maps, channel maps, spectra, and velocity fields ofmolecular emission in nearby galaxies.