Observations of OH and CO in the Orion Molecular Cloud

The results of millimeter and submillimeter observations of the BN-KL region of the Orion molecular cloud are reported. Observations were made with a 91 cm bent Cassegrain telescope fitted with an interferometer/grating spectrometer during flights at 13-14 km altitude in the NASA Kuiper Observatory. The data collected covered the 2Pi(1/2)J = 3/2 yields 1/2 and 2Pi(3/2)J = 7/2 yields 5/2 rotational transitions of OH. The measurements were made at 163 and 84 micron wavelengths, respectively. The OH emitting regions was estimated to have a temperature of 1000 K and a molecular hydrogen density of about 6 million/cu cm. Depopulation of the excited states of OH was caused primarily by collisional excitation. The OH fill factor for the region survey was about 10 percent, in line with predictions for a post-shocked region.