A blind survey of the 6.7 GHz methanol maser line

Abstract

A blind survey for 6.7 GHz methanol maser emission has been made with the 32 m Toruri radio telescope. The survey consists of 4,800 spectra on an equilateral triangular grid pattern with each grid point separated by 4~4 covering a field of rv21 deg 2 at galactic longitudes 20 0to 40 0and galactic latitudes ±0~52. The average sensitivity was 1.6 Jy and the spectral resolution was 0.04 km s-l. A total of 99 sources were detected, 28 of which were not found during previous searches of IRASselected ultracompact HII regions. The peak flux density of new detections is usually lower than 30 Jy. About half of the methanol masers have no IRAS counterparts within a radius of 2'. The nature of these sources is unclear.