The Faint Optical Counterparts Catalog at 19.4 < r < 22 mag from Herschel-ATLAS SDP Field

Abstract

We carry out a spectroscopic survey with Hectospec mounted on the 6.5 m Multiple Mirror Telescope to obtain redshifts of optical counterparts of the Herschel-ATLAS sources in the science demonstration phase field. Our work concerns counterparts with a magnitude range at $19.4\lt {r}_{\mathrm{SDSS}}\lt 22$ mag. The observation covers two $\sim 1\ {\deg }^{2}$ pointings. In total, we newly obtain redshifts of 158 potential counterparts. Among these counterparts, there are 59 high reliability counterparts. For these high reliability counterparts, we do a SED fitting using MAGPHYS with our spectroscopic redshifts and five Herschel band fluxes, and discover 46 new luminous infra-red galaxies and 10 new ultra luminous infra-red galaxies, including two infra-red QSOs.