Molecular gas in the Galactic center region .1. Data from a large scale (CO)-O-18(J=1->0) survey

Abstract

A large scale survey of the Galactic center region in the (CO)-O-18(J = 1 --> 0) transition is presented. This survey was obtained with the 1.2 m Southern Millimeter-Wave Telescope (SMWT) at the Cerro Tololo Interamerican Observatory (CTIO) near La Serena, Chile. It covers the region 1.degrees 05 less than or equal to iota less than or equal to +3.degrees 6 and -0.degrees 9 less than or equal to b less than or equal to +0.degrees 75 with a grid spacing of 9', i.e. the sampling is at full FWHP beamwidth. 357 positions were in total observed. After reviewing the instrumentation of the 1.2m SMWT, the observing techniques, and the methods used in the data reduction, the data of the survey are presented and morphologically described. In addition, data of the HNCO(5(0,5) -4(0,4)) line are presented, which was also included in the large bandwidth of the spectrometer. (CO)-C-12(1 - 0) measurements performed for comparison purposes are presented and compared with other (CO)-C-12 results The maps of the (CO)-O-18(1 - 0) survey demonstrate that there are great differences between the distribution of the optically thin (CO)-O-18(1 - 0) emission and the usually optically thick (CO)-C-12(1 - 0) emission.