Multiwavelength OH observations of Mon R2 during 4765 MHz OH maser flaring

Abstract

During the spectacular 4765 MHz excited OH maser flaring episodes observed in Mon R2 from 1994 to 1998 (Smits et al. 1998), observations were made at the line frequencies of other OH transitions. No excited OH lines were detected, nor were any 1612 or 1720 MHz OH masers found in Mon R2. 1665 and 1667 MHz OH masers were present and underwent small changes. With a peak flux of ∼ 75 Jy, the null detections and small variations at other wavelengths put strong constraints on models of OH masers.