The BIMA Survey of Nearby Galaxies is a systematic imaging study of the 3 mm CO J = 1–0 molecular emission within the centers and disks of 44 nearby spiral galaxies .
The typical spatial resolution of the survey is 6″ or 360 pc at the average distance ( 12 Mpc ) of the sample .
The velocity resolution of the CO observations is 4 km s ^ { -1 } , though most maps are smoothed to 10 km s ^ { -1 } resolution .
For 33 galaxies , multi-field observations ensured that a region \gtrsim 190″ ( < D > = 10 kpc ) in diameter was imaged .
For the remaining 11 galaxies , which had smaller optical diameters and were on average farther away , single-pointing observations imaged a 100″-diameter ( < D > = 11 kpc ) region .
The sample was not chosen based on CO or infrared brightness ; instead , all spirals were included that met the selection criteria of v _ { \sun } \leq 2000 km s ^ { -1 } , \delta \geq -20° , i \leq 70° , D _ { 25 } < 70′ , and B _ { T } < 11.0 .
The detection rate was 41/44 sources or 93 % ; of the three nondetections , one ( M 81 ) is known to have CO emission at locations outside the survey field of view .
Fully-sampled single-dish CO data were incorporated into the maps for 24 galaxies ; these single-dish data comprise the most extensive collection of fully-sampled , two-dimensional single-dish CO maps of external galaxies to date .
We also tabulate direct measurements of the global CO flux densities for these 24 sources .
For the remaining 20 sources , we collected sensitive single-dish spectra in order to evaluate the large-scale flux recovery .
We demonstrate that the measured ratios of flux density recovered are a function of the signal-to-noise of the interferometric data .
We examine the degree of central peakedness of the molecular surface density distributions and show that the distributions exhibit their brightest CO emission within the central 6″ in only 20/44 or 45 % of the sample .
We show that all three Local Group spiral galaxies have CO morphologies that are represented in SONG , though the Milky Way CO luminosity is somewhat below the SONG average , and M31 and M33 are well below average .
This survey provides a unique public database of integrated intensity maps , channel maps , spectra , and velocity fields of molecular emission in nearby galaxies .
It also lays the groundwork for extragalactic surveys by more powerful future millimeter-wavelength interferometers like CARMA and ALMA .