A line survey of Orion-KL from 607 to 725 GHz

With the Caltech Submillimeter Telescope, we have performed an unbiased line survey of Orion-KL in the frequency range 607-725 GHz. We were able to identify lines down to a threshold of 1-2 K in main beam brightness temperature units, and we found 1064 spectral features consisting of 2032 lines, partially blended. Apart from the abundant diatomic rotors such as CO, CS, SO, the spectrum is dominated by CH3OH and SO2, both in terms of numbers of lines and integrated flux. The number of unidentified lines is 155 or 14%. We also report the tentative identification of the new molecule SiH in our data. For some complex organic molecules, we find rotation temperatures and column densities which are much higher than those found in earlier studies. It is likely the cause of this is a significant contribution from a very compact, hot component of the Orion molecular cloud core which was not visible in lower frequency surveys.