Published online by Cambridge University Press: 04 August 2017
The three existing spectral surveys in the 3 mm window are compared. the NRAO and BTL surveys of SgrB2 are quite consistent, the NRAO and Onsala surveys of Ori(KL) less so. Lists of U-lines are assembled from the three surveys, and total 86 in Ori(KL), 66 in SgrB2, of which only 12 are common. Difficulties in selecting reliable lists of U lines are emphasized. Methods of identifying such lines include “direct,” “hybrid,” and “Shotgun” approaches; the probability of misidentification is analyzed for each. the “Shotgun” method is least reliable, although a few candidates should be followed up.