1996A&A...315..521E

The two OH maser emitters with the designation OH 57.5+1.8 and velocities -75 and +40km/s, discovered within one pointing by OH maser surveys, are shown to belong to the IRAS sources 19295+2228 and 19296+2227. The first is a well known OH/IR star, while the second is suggested to be a proto-planetary nebula. The latter classification is inferred from the peculiar properties of the OH maser and those of a newly discovered H₂O maser. If correct, the search for peculiar maser properties among IRAS sources with colors typical for late AGB stars may allow the discovery of proto-planetary nebulae in a very early stage of their departure from the AGB. OH maser spectra with high velocity resolution of the OH/IR stars OH 66.8-1.2 and AFGL 4259 are displayed in addition to those of OH 57.5+1.8, showing that their two maser components are blends. The spectra support models of the circumstellar outflow, which predict clumpiness in the OH maser shell.