We report on the first spectral and timing characterization of the transient X-ray source 1RXS J194211.9+255552 using all available data from the Swift X-ray satellite .
We used 10 years of hard X-ray data from the Burst Alert Telescope , to characterize its long-term behaviour and to search for long periodicities , finding evidence for a periodic modulation at 166.5 \pm 0.5 days , that we interpret as the orbital period of the source .
The folded light curve reveals that the X-ray emission is mostly concentrated in a restricted phase-interval and we propose to associate 1RXS J194211.9+255552 to the class of the Be X-ray binaries .
This is also supported by the results of the spectral analysis , where we used the BAT data and three pointed Swift /XRT observations to characterize the X-ray broadband spectral shape .
We found mild spectral variability in soft X-rays that can be accounted for by a varying local neutral absorber , while the intrinsic emission is consistent with a hard power-law multiplied by a high-energy exponential cut-off as typically observed in this class of systems .