A Large Extension of the CfA Galactic CO Survey

The Galactic CO survey of Dame, Hartmann, & Thaddeus (2001; hereafter DHT) is composed of both large-scale unbiased surveys, mainly concentrated within 10 • of the Galactic plane, and targeted observations of clouds at higher latitudes. Analysis of all-sky IRAS and 21 cm maps suggests that the DHT survey is nearly complete for clouds larger than ∼ 1 • , even though roughly half of the total area at |b| < 30 • was not observed. In October 2001 we began a new survey of all of this unobserved area that is accessible to the northern 1.2 meter telescope, approximately 6,600 deg 2 between l = 0 • and 230 • , mainly in the latitude range |b| = 10 • –30 •. At least 12 hours per day is being dedicated to this large project, which is sampled every 1 / 4 • (every other beamwidth) to an rms sensitivity of 0.19 K at a velocity resolution of 0.65 km s −1. As of May 2003, we have obtained 90,000 of the 106,000 spectra required to complete the survey. While, as expected, the new observations do not substantially change the DHT map, 68 relatively small and isolated molecular clouds at intermediate latitudes have so far been discovered. The survey has also been extended to b < −30 • in two regions, one in the vicinity of the large MBM clouds 53-55 at l ∼ 90 • and the other south of the Taurus clouds at l ∼ 170 •. Substantial amounts of molecular gas were detected in both of these high-latitude regions.