Detection and Confirmation of Interstellar Acetic Acid

We have detected acetic acid (CH₃COOH) in the Sgr B2 Large Molecule Heimat source using the Berkeley-Illinois-Maryland Association (BIMA) Array and the Caltech Owens Valley Radio Observatory (OVRO) Millimeter Array. With the BIMA array, we initially detected the 8_*,8-7_*,72 A blend near 90.2 GHz. The corresponding line from the E symmetry species was sought but may be blended with a line from another species. Interstellar CH₃COOH was confirmed using the OVRO array, with which we detected the 9_*,9-8_*,8 E blend near 100.9 GHz. The corresponding line from the A symmetry species was sought but was found to be blended with the 7₁-7₀ E line of CH₃SH. Our CH₃COOH observations represent the first detection and confirmation of an interstellar molecule using interferometric arrays; all past detections and confirmations of new molecules have been made on the basis of single-element telescope observations.