Monitoring of 6-cm excited OH masers -- II

Abstract

A search towards 69 star-forming regions has led to the discovery of three new 4765-MHz excited OH masers. No 4750- or 4660-MHz excited OH masers were detected above a level of ∼ 1 Jy. The results of monitoring nine sources of 4765-MHz excited OH masers for periods of up to 7 yr are reported. Many of the linewidths are narrow and have had constant widths and centroid velocities throughout the monitoring period. The maser flux of one source was constant over 7 yr while in the most extreme case of variability the flux doubled in a period of 2 weeks.