Spectral scan of Orion A and IRC +10216 from 72 to 91 GHz.

The spectra of the Orion KL molecular cloud and the envelope of the carbon star IRC +10216 have been surveyed at 1 MHz resolution over the interval 72.2 - 91.1 GHz to a sensitivity usually better than 0.1K. Some complementary data have been obtained at selected higher and lower frequencies. Approximately 170 lines from 24 known interstellar molecules were detected in Orion; the corresponding numbers for IRC +10216 are 45 and 12, respectively. Some 15 recombination lines of hydrogen (α, β, γ, δ) and helium (α) are also identified in Orion. More than 100 of the Orion lines can be attributed to astronomically new transitions. Line identifications are given and a multi-transition analysis of several molecular species is presented and gives information on physical conditions and chemical abundances in the Orion KL region. The excitation conditions and relative abundances in the IRC +10216 envelope are reviewed. In addition, selected data, mainly on methanol lines, are given for W 51 M.