Water maser emission in IC 342

The detection of 22 GHz water vapor emission from IC 342 is reported, raising the detection rate among northern galaxies with IRAS point source fluxes S-100mum > 50 Jy to 16%. The maser, associated with a star forming region similar to10-15 west of the nucleus, consists of a single 0.5 km s(-1) wide feature and reaches an isotropic luminosity of 10(-2) L-circle dot (D = 1.8 Mpc). If the time variability is intrinsic, the maser size is less than or similar to1.5 x 10(16) cm (less than or similar to0.5 mas) which corresponds to a brightness temperature of greater than or similar to10(9) K. The linewidth, luminosity, and rapid variability are reminiscent of the 8 km s(-1) super maser in Orion-KL. A velocity shift of 1 km s(-1) within two weeks and subsequent rapid fading is explained in terms of a chance alignment of two dense molecular clouds. Observations at 22 GHz toward Maffei 2 are also reported, yielding a 5sigma upper limit of 25 mJy for a channel spacing of 1.05 km s(-1).