POSITIONS OF HYDROXYL MASERS AT 1665 AND 1667 MHZ

The Australia Telescope Compact Array has been used to observe more th an 200 1665-MHz hydroxyl masers south of declination -16 degrees and d erive their positions with typical rms uncertainties of 0.4 arcsec. Ma ny of the 1665-MHz maser sites are found to have 1667-MHz OH maser cou nterparts which are coincident, within the errors. The resulting posit ion list presented here includes all well-documented, previously repor ted 1665-MHz masers close to the Galactic plane in the galactic longit ude range 230 degrees (through 360 degrees) to 13 degrees. Nearly 50 n ewly discovered masers are also listed, chiefly in the longitude range 312 degrees to 356 degrees, where the observations were conducted as an intensive survey of a continuous zone close to the Galactic plane. Many of the maser sites are discussed briefly so as to draw attention to those possessing properties that are unusual among this large sampl e. Most of the masers are of the variety found in star-forming regions - at the sites of newly formed massive stars and their associated ult racompact HII regions. The new, accurate, positions reveal coincidence s of the OH masers with the continuum radio emission, with the infrare d emission from dust that accompanies such regions, and with emission from other maser species such as methanol at 6668 MHz and water at 22 GHz. By-products of the survey, also presented here, include measureme nts of at least 11 objects that are not associated with massive star-f orming regions. They comprise several OH/IR stars (detected at the 166 7- or 1665-MHz transition of OH, though commonly found to be most prom inent at the 1612-MHz transition) and several unusual masers that may pinpoint other varieties of late-type stars or protoplanetary nebulae. (C) 1998 RAS.