The ATCA/VLA OH 1612 MHz survey^*,**

III. Observations of the Northern Galactic Plane

¹ MSSSO/RSAA, Cotter Road, Weston ACT 2611, Australia
² Joint Institute for VLBI in Europe, Postbus 2, 7990 AA Dwingeloo, The Netherlands
³ Australia Telescope National Facility, PO Box 76, Epping NSW 1710, Australia
⁴ Sterrewacht Leiden, PO Box 9513, 2300 RA Leiden, The Netherlands

Corresponding author: M. Sevenster, msevenst@mso.anu.edu.au

Received: 20 July 2000
Accepted: 9 November 2000

Abstract

We present observations of the region between and , in the OH 1612.231 MHz line, taken from 1993 to 1995 with NRAO's Very Large Array (VLA). These observations are the last part of a larger survey, covering and , with the Australia Telescope Compact Array (ATCA) and the VLA. The region was systematically observed on a grid in () and the resulting coverage was 92% , with 965 pointings. We found 286 OH-masing objects, 161 of which are new detections and 207 have reliable IRAS point-source identifications. The outflow velocity was determined for 276 sources. A total of 766 sources were detected in the combined ATCA/VLA survey, of which 29 were detected in two regions of the survey. In this article we analyse the data statistically and give identifications with known sources where possible. The "efficiency"of this VLA survey is 75% of that of the ATCA Bulge survey. This efficiency was determined by comparing the detections in the region where the two surveys overlap. The completeness-and error characteristics are similar, though less homogeneous, except for the much larger errors in the flux densities. The relatively large surface number density found in the northern disk, suggests that we can see the Bar extending to higher longitudes on this side of the galactic Centre.