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B. D. Oppenheimer, I. J. Daubar (NAIC, Arecibo Observatory)
We present Arecibo observations of 10 OH/IR stars in the 1612, 1665, and 1667 MHz bands from July 1998. These stars were previously detected in the Arecibo 1612 MHz survey of color selected IRAS sources and were later detected in the main lines as well. We wish to determine if the OH emissions are variable. Changes in OH emission may signal the evolution of the system with respect to its mass loss rate and the conditions within its circumstellar shell. We find that all 10 sources show both 1612 MHz and 1667 MHz emission but only six of the sources show 1665 MHz emission. Some of the sources indicate a variation in line strengths, notably 18455+0448 which has weakened dramatically at 1612 MHz and strengthened at 1667 MHz.