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Published online by Cambridge University Press: 04 August 2017
A spectral line survey for interstellar NH3 is being carried out using the 64-m telescopes at Parkes and Tidbinbilla. Both telescopes are equipped with K-band masers yielding system temperatures below 100 K. The preliminary survey was to be made with the Parkes antenna (beam = 1.5′ arc) with follow-up mapping of the more interesting sources at Tidbinbilla (beam = 0.9′ arc). Sources have in general been H II regions from the H2CO surveys made at Parkes. Approximately 70 sources (out of a target of (∼ 100) have been observed simultaneously in the metastable (1,1), (2,2) and (3,3) transitions. The (1,1) line has been detected in about 70% of the sources surveyed. The other lines which involve higher excitation are detected primarily in the more compact sources, particularly those associated with OH and H2O masers. Examples are given of spectra for different types of source.