An unprocessed frequency-switched scan of Comet Hale-Bopp taken 6 weeks prior to perihelion. The detected lines appear as positive and negative pairs in this mode of observing. The receiver was tuned in double-side band mode. The broad lines originate in the comet. They are the HCN 4-3 transition on the left (845.7um) and the CO 3-2 transition (867.0 um). The narrow features on the right arise from the CO3-2 line in the earth's atmosphere. (Courtesy H.E. Matthews, D. Jewitt, M. Senay)