2002PASP..114..416R

We have searched for nonastrophysical emission lines in the optical spectra of 577 nearby F, G, K, and M main-sequence stars. Emission lines of astrophysical origin would also have been detected, such as from a time-variable chromosphere or infalling comets. We examined ∼20 spectra per star obtained during 4 years with the Keck/High Resolution Echelle Spectrometer at a resolution of 5 km.s^–1, with a detection threshold 3% of the continuum flux level. We searched each spectrum from 4000 to 5000 Å for emission lines having widths too narrow to be natural from the host star, as well as for lines broadened by astrophysical mechanisms. We would have detected lasers that emit a power P>50 kW for a typical beamwidth of ∼0".01 (diffraction limit from a 10 m aperture) if directed toward Earth from the star. No lines consistent with laser emission were found.