Accurate OH Maser Positions. II. the Galactic Center Region

We present high spatial resolution observations of ground-state OH masers achieved using the Australia Telescope Compact Array (ATCA). These observations were conducted toward 171 pointing centers where OH maser candidates were identified previously in the Southern Parkes Large-Area Survey in Hydroxyl toward the Galactic center region between Galactic longitudes of 355 and 5 and Galactic latitudes of -2° and +2°. We detect maser emission toward 162 target fields and suggest that six out of nine nondetections are due to intrinsic variability. Due to the superior spatial resolution of the follow-up ATCA observations, we have identified 356 OH maser sites in the 162 target fields with maser detections. Almost half (161 of 356) of these maser sites have been detected for the first time in these observations. After comparing the positions of these 356 maser sites to the literature, we find that 269 (76%) sites are associated with evolved stars (two of which are PNe), 31 (9%) are associated with star formation, and four are associated with supernova remnants; we were unable to determine the origin of the remaining 52 (15%) sites. Unlike the pilot region, the infrared colors of evolved star sites with symmetric maser profiles in the 1612 MHz transition do not show obvious differences compared with those of evolved star sites with asymmetric maser profiles. © 2018. The American Astronomical Society. All rights reserved.The Australia Telescope Compact Array is part of the Australia Telescope, which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO. This research has made use of NASA's Astrophysics Data System Abstract Service and the SIMBAD database, operated at CDS, Strasbourg, France. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). This publication also makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California Institute of Technology, funded by NASA. H-HQ is partially supported by the Special Funding for Advanced Users, budgeted and administrated by the Center for Astronomical Mega-Science, Chinese Academy of Sciences (CAMS-CAS), and CAS >Light of West China> Program. JFG is partially supported by MINECO (Spain) grants AYA2014-57369-C3-3 and AYA2017-84390-C2-1-R (cofunded by FEDER). This work was supported in part by the Major Program of the National Natural Science Foundation of China (grant Nos. 11590780 and 11590784) and the CAS Pioneer Hundred Talents Program (Technological excellence, Y650YC1201)