The \emph{Fermi} Large Area Telescope (LAT) discovered a new gamma-ray source near the Galactic plane, \object{Fermi J0109+6134}, when it flared brightly in 2010 February. The low Galactic latitude (b =-1.2\degr) indicated that the source could be located within the Galaxy, which motivated rapid multi-wavelength follow-up including radio, optical, and X-ray observations. We report the results of analyzing all 19 months of LAT data for the source, and of X-ray observations with both \emph{Swift} and the \emph{Chandra X-ray Observatory}. We determined the source redshift, z =0.783, using a Keck LRIS observation. Finally, we compiled a broadband spectral energy distribution (SED) from both historical and new observations contemporaneous with the 2010 February flare. The redshift, SED, optical line width, X-ray absorption, and multi-band variability indicate that this new GeV source is a blazar seen through the Galactic plane. Because several of the optical emission lines have equivalent width >5\AA, this blazar belongs in the flat-spectrum radio quasar category.
@article{arxiv.1004.1413,
title = {Discovery of a GeV blazar shining through the Galactic plane},
author = {J. Vandenbroucke and R. Buehler and M. Ajello and K. Bechtol and A. Bellini and M. Bolte and C. C. Cheung and F. Civano and D. Donato and L. Fuhrmann and S. Funk and S. E. Healey and A. B. Hill and C. Knigge and G. M. Madejski and R. W. Romani and M. Santander-García and M. S. Shaw and D. Steeghs and M. A. P. Torres and A. Van Etten and K. A. Williams},
journal= {arXiv preprint arXiv:1004.1413},
year = {2010}
}