A Multi-Line Ammonia Survey Of The Galactic Center Region With The Tsukuba 32 M Telescope. I. Observations And Data

We present survey data of six NH3 (J, K) = (1, 1), (2, 2), (3, 3), (4, 4), (5, 5), and (6, 6) lines, simultaneously observed with the Tsukuba 32 m telescope, in the main part of the central molecular zone of the Galaxy. The total number of on-source positions was 2655. The three lower transitions were detected with S/N > 3 at 2323 positions (93% of all the on-source positions). Among 2323, the S/N's of (J, K) = (4, 4), (5, 5), and (6, 6) exceeded 3.0 at 1426(54%), 1150(43%), and 1359(51%) positions, respectively. Simultaneous observations of the lines enabled us to accurately derive intensity ratios with less systematic errors. Boltzmann plots indicate that there are two temperature components: cold (similar to 20 K) and warm (similar to 100 K). Typical intensity ratios of T-mb (2, 2)/T-mb(1, 1), T-mb(4, 4)/T-mb(2, 2), T-mb(5, 5)/T-mb(4, 4), and T-mb(6, 6)/T-mb(3, 3) were 0.71, 0.45, 0.65, and 0.17, respectively. These line ratios correspond to the diversity of the rotational temperature, which results from mixing of the two temperature components.