Positions of OH maser sources determined with the 100-m telescope

Abstract

Positions of 65 OH maser sources obtained with the 100-m radio telescope are presented. The positional accuracy is typically 10'', a conservative estimate for sources stronger than approx.10 Jy. The emphasis of this work was on OH/IR sources and 51 of the objects are certain type II OH/IR sources, of which only one (GX Mon) is associated with an optically known star. Three of the sources show only one 1612-MHz line component and these are probably also OH/IR sources but with a large ratio between the intensities of the high- and low-velocity components. Six of the objects are certain type I OH sources, i.e., maser emission associated with recently formed massive stars, and five more are probably of this type, although in some of these cases the 1612-MHz line is stronger than one of the main lines. This work has incidentally revealed (i) that the 1665-MHz emission which previously was assumed to be positionally coincident with the 1720-MHz emission of the source ON-3 originates approx.2.'3 to the southwest of the interferometrically determined 1720-MHz position, and (ii) that to within the positional accuracy, the position of the 1612-MHz emission from the core of the Kleinmann--Low nebula (Orion) is the same as more » that of the 1665-MHz emission; (iii) that the position of the 1667-MHz emission from VX Sgr is the same as that of the 1612-MHz emission; and (iv) that the position of the 1612-MHz emission from W 3(OH) is the same as that of the 1665/1667-MHz emission. « less