PHOTOMETRICALLY TRIGGERED KECK SPECTROSCOPY OF<i>FERMI</i>BL LACERTAE OBJECTS

We report on Keck spectra of ten Fermi blazars. J0622+3326, previously\nunobserved, is shown to be a flat-spectrum radio quasar at redshift z=1.062.\nThe others are known BL Lac-type objects that have resisted previous attempts\nto secure redshifts. Using a photometric monitoring campaign with the 0.76 m\nKatzman Automatic Imaging Telescope at Lick Observatory, we identified epochs\nwhen the relativistic jet emission was fainter than usual, thus triggering the\nKeck spectroscopy. This strategy gives improved sensitivity to stars and\nionized gas in the host galaxy, thereby providing improved redshift constraints\nfor seven of these sources.\n