The Bell Laboratories 13 CO Survey: Longitude‐Velocity Maps

Abstract

A survey is presented of the Galactic plane in the J \ 1È0 transition of 13CO. About 73,000 spectra were obtained with the 7 m telescope at Bell Laboratories over a 10 yr period. The coverage of the survey is (l, b) \ ([5¡ to 117¡, [1¡ to 1¡), or 244 deg2, with a grid spacing of 3@ for and a grid o b o \ 0¡ .5 spacing of 6@ for The data presented here have been resampled onto a 3@ grid. For 0.68 km o b o [ 0¡ .5. s~1 channels, the rms noise level of the survey is 0.1 K on the scale. The raw data have been trans-T R * formed into FITS format, and all the reduction processes, such as correcting for emission in the reference positions, baseline removal, and interpolation, were conducted within IRAF using the FCRAO task package and additional programs. The reduced data are presented here in the form of longitude-velocity color maps at each latitude. These data allow identiÐcation and classiÐcation of molecular clouds with masses in excess of D103 throughout the Ðrst quadrant of the Galaxy. Spiral structure is manifested M _ by the locations of the largest and brightest molecular clouds.