20 GHz Continuum and SiS Maser Emission from IRC+10216

We are monitoring the SiS (1–0) maser line at 18.19 GHz from the late-type carbon star IRC+10216 (CW Leo) over the infrared light cycle (644 days) using the OVRO 40-m radio telescope and a supercooled K-band maser receiver. We have also searched for, discovered, and are monitoring continuum emission at 20 GHz from the star using the same telescope system. The detection of the SiS maser lines in IRC+10216 (Grashoff et al. 1981) is the first evidence of maser activity in any carbon-rich stellar envelope and the interpretation of the masers is important in understanding the physics and chemistry of the circumstellar shell.