The arizona radio observatory CO mapping survey of galactic molecular clouds. I. the W51 region in CO and ¹³CO J = 2-1 emission

We present 38'' resolution maps of the CO and ¹³CO J = 2-1 lines in the molecular clouds toward the HII region complex W51. The maps cover a 1.°25 × 1° section of the galactic plane and span +30 to +85 km s^-1 (LSR) in velocity. The spectral resolution is ̃1.3 km s ^-1. The velocity range of the images includes all the gas in the Sagittarius spiral arm. Color figures display the peak line brightness temperature, the velocity-integrated intensity, and 2 km s^-1 channel-averaged maps for both isotopologs, and also the CO/¹³CO J = 2-1 line intensity ratio as a function of velocity. The CO and ¹³CO line intensity image cubes are made available in standard FITS format as electronically readable tables. We compare our molecular line maps with the 1.1 mm continuum image from the BOLOCAM Galactic Plane Survey. From our ¹³CO image cube, we derive kinematic information for the 99 BGPS sources in the mapped field in the form of Gaussian component fits. The integrated ¹³CO line intensity and the 1.1 mm source flux density show only a modest degree of correlation for the 99 sources, likely due to a range of dust and gas physical conditions within the sources. However, the 1.1 mm continuum surface brightness and the integrated ¹³CO line intensity for small regions containing single BGPS sources and molecular clouds show very good correlations in many cases. Differences in the shapes of these correlations from one spatial region to another probably result from different physical conditions or structure in the clouds.