in Table \[table:sample\]. However, we emphasize that this is not a complete sample of all the water megamasers known today, which can be found in @2015ApJ...810...65P.

Data reduction
--------------

We present *NuSTAR* hard X-ray spectral results for 11 sources. In particular, we use archival data for NGC 1194, NGC 1386, NGC 2273, NGC 2960, NGC 3079, NGC 3393, NGC 4388 and IC 2560, for which observation dates and exposure times can be found in Table \[table:obs\]. For NGC 4945, NGC 1068 and the Circinus galaxy spectral parameters are taken from @2014ApJ...793...26P, @2014arXiv1411.0670B and @2014ApJ...791...81A, respectively. The raw events files were processed using the [*NuSTAR*]{} Data Analysis Software package v. 1.4.1 (NuSTARDAS)[^2]. Calibrated and cleaned event files were produced using the calibration files in the [*NuSTAR*]{} CALDB (20150225) and standard filtering criteria with the `nupipeline` task. We used the `nuproducts` task included in the NuSTARDAS package to extract the [*NuSTAR*]{} source and background spectra using the appropriate response and ancillary files. We extracted spectra and light curves in each focal plane module using circular apertures of different radii, aimed at optimizing the signal to noise ratio at high energies for every source (see Baloković et al. in prep., for further details). 