  The LAMOST-Kepler survey, whose spectra are analyzed in the present paper, is
the first large spectroscopic project aimed at characterizing these sources.
Our work is focused at selecting emission-line objects and chromospherically
active stars and on the evaluation of the atmospheric parameters. We have used
a version of the code ROTFIT that exploits a wide and homogeneous collection of
real star spectra, i.e. the Indo US library. We provide a catalog with the
atmospheric parameters (Teff, logg, [Fe/H]), the radial velocity (RV) and an
estimate of the projected rotation velocity (vsini). For cool stars (Teff<6000
K) we have also calculated the H-alpha and CaII-IRT chromospheric fluxes. We
have derived the RV and the atmospheric parameters for 61,753 spectra of 51,385
stars. Literature data for a few hundred stars have been used to do a quality
control of our results. The final accuracy of RV, Teff, logg, and [Fe/H]
measurements is about 14 km/s, 3.5%, 0.3 dex, and 0.2 dex, respectively.
However, while the Teff values are in very good agreement with the literature,
we noted some issues with the determination of [Fe/H] of metal poor stars and
the tendency, for logg, to cluster around the values typical for main sequence
and red giant stars. We propose correction relations based on these comparison.
The RV distribution is asymmetric and shows an excess of stars with negative
RVs which is larger at low metallicities. We could identify stars with variable
RV, ultrafast rotators, and emission-line objects. Based on the H-alpha and
CaII-IRT fluxes, we have found 442 chromospherically active stars, one of which
is a likely accreting object. The availability of precise rotation periods from
the Kepler photometry has allowed us to study the dependency of the
chromospheric fluxes on the rotation rate for a quite large sample of field
stars.
