Water masers in M31. I. Recombination lines

We include the 206 sources observed in the Darling water maser survey for completeness. The survey was sensitive enough to detect any maser useful for ~10{mu}as/yr astrometry.

No new water masers, ammonia lines, or H66{alpha} recombination lines were detected individually or in spectral stacks reaching rms noise levels of ~3mJy and ~0.2mJy, respectively, in 3.1-3.3km/s channels. The lack of detections in individual spectra and in the spectral stacks is consistent with Galactic extrapolations. Contrary to previous assertions, there do not seem to be any additional bright water masers to be found in M31.