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We present "On The Fly" maps of the CO(1-0) and CO(2-1) emission covering a10' X 10' region of the NGC 6946. Using our CO maps and archival VLA HIobservations we create a total gas surface density map, Sigma_gas, for NGC6946. The predominantly molecular inner gas disk transitions smoothly into anatomic outer gas disk, with equivalent atomic and molecular gas surfacedensities at R = 3.5' (6 kpc). We estimate that the total H2 mass is 3 X 10^9Mo, roughly 1/3 of the interstellar hydrogen gas mass, and about 2% of thedynamical mass of the galaxy at our assumed distance of 6 Mpc. The value of theCO(2-1)/CO(1-0) line ratio ranges from 0.35 to 2; 50% of the map is covered byvery high ratio, >1, gas. The very high ratios are predominantly from interarmregions and appear to indicate the presence of wide-spread optically thin gas.Star formation tracers are better correlated with the total neutral gas diskthan with the molecular gas by itself implying SFR is proportional toSigma_gas. Using the 100 FIR and 21 cm continuum from NGC 6946 as starformation tracers, we arrive at a gas consumption timescale of 2.8 Gyr, whichis relatively uniform across the disk. The high star formation rate at thenucleus appears to be due to a large accumulation of molecular gas rather thana large increase in the star formation efficiency. The mid-plane gas pressurein the outer (R > 10 kpc) HI arms of NGC 6946 is close to the value at theradial limit (10 kpc) of our observed CO disk. If the mid-plane gas pressure isa factor for the formation of molecular clouds, these outer HI gas arms shouldcontain molecular gas which we do not see because they are beyond our detectionlimit.

CO(1-0), CO(2-1) and Neutral Gas in NGC 6946: Molecular Gas in a Late-Type, Gas Rich, Spiral Galaxy