A SEARCH FOR WATER AND MAINLINE OH MASERS FROM OH IR STAR COLOR MIMICS/

About 40 per cent of colour-selected IRAS sources are without 1612-MHz masers, despite IR colours that are indicative of thick circumstellar shells, and often despite spectral classifications showing that they are O-rich. We report here on a search for water and mainline OH maser s from the 26 OH/IR star colour mimics identified by Lewis with a 2n-3 n LRS type. We find water masers in six, and mainline masers in a furt her five. These 11 sources are indubitably O-rich, and many have a vel ocity range characteristic of, and appropriate to, masers associated w ith circumstellar shells. However, 17 per cent of 2n-3n sources appear to have. no circumstellar masers; we estimate that 11 per cent may ne ver exhibit a maser.