Searches for H$_2$O Masers toward Narrow-Line Seyfert 1 galaxies
  We present searches for 22 GHz H$_2$O masers toward 36 narrow-line Seyfert 1
galaxies (NLS1s), selected from known NLS1s with $v_{sys}$ $\lesssim$ 41000
km/s. Out of the 36 NLS1s in our sample, 11 NLS1s have been first surveyed in
our observations, while the observations of other NLS1s were previously
reported in literature. In our survey, no new water maser source from NLS1s was
detected at 3 $\sigma$ rms level of 8.4 mJy to 144 mJy, which depends on
different observing conditions or inhomogeneous sensitivities of each
observation using three different telescopes. It is likely that non-detection
of new masers in our NLS1 sample is primarily due to insufficient sensitivities
of our observations. Including the five known NLS1 masers, the total detection
rate of the H$_2$O maser in NLS1s is not remarkably different from that of type
2 Seyfert galaxies or LINERs. However, more extensive and systematic searches
of NLS1 would be required for statistical discussion of the detection rate of
the NLS1 maser, compared with that of type 2 Seyferts or LINERs.
