Molecular line survey of Orion A from 215 to 247 GHz.

Molecular line emission from the core of the Orion molecular cloud has been observed in the frequency range 215-247 GHz to an average sensitivity of about 0.2 K. The observations were carried out using the 1.3-mm spectroscopy system of the Owens Valley Radio Observatory. The bandwidth of the telescope was 0.5 arcmin averaged over the frequency range. A total of 544 resolvable lines were detected, of which 517 were positively identified and attributed to 25 chemical species. The most abundant molecules were HCOOCH3, CH3OCH3, and C2H5CN, with column densities of about 3 x 10 to the 15th per sq cm. Together with SO2, CH3OH, and CH3CN, the above lines account for about 70 percent of the lines in the spectrum. The molecular line spectra are reproduced in graphic form.