Martin, Nicolas F.Schlafly, Edward F.Slater, Colin T.Bernard, Edouard J.Rix, Hans-WalterBell, Eric F.Ferguson, Annette M. N.Finkbeiner, DouglasLaevens, Benjamin P. M.Burgett, William S.Chambers, Kenneth C.Draper, Peter W.Hodapp, Klaus W.Kaiser, NicholasKudritzki, Rolf-PeterMagnier, Eugene A.Metcalfe, NigelMorgan, Jeffrey S.Price, Paul A.Tonry, John L.Wainscoat, Richard J.Waters, Christopher2017-07-182013Martin, Nicolas F., Edward F. Schlafly, Colin T. Slater, Edouard J. Bernard, Hans-Walter Rix, Eric F. Bell, Annette M. N. Ferguson, et al. 2013. “Perseus I: A Distant Satellite Dwarf Galaxy of Andromeda.” The Astrophysical Journal 779 (1) (November 26): L10. doi:10.1088/2041-8205/779/1/l10.2041-8205http://nrs.harvard.edu/urn-3:HUL.InstRepos:33462041We present the discovery of a new dwarf galaxy, Perseus I/Andromeda XXXIII, found in the vicinity of Andromeda (M31) in stacked imaging data from the Pan-STARRS1 3π survey. Located 27fdg9 away from M31, Perseus I has a heliocentric distance of 785 ± 65 kpc, compatible with it being a satellite of M31 at $374^{+14}_{-10}{\rm \,kpc}$ from its host. The properties of Perseus I are typical for a reasonably bright dwarf galaxy (MV = –10.3 ± 0.7), with an exponential half-light radius of rh = 1.7 ± 0.4 arcmin or $r_h = 400^{+105}_{-85}{\rm \,pc}$ at this distance, and a moderate ellipticity ($\epsilon = 0.43^{+0.15}_{-0.17}$). The late discovery of Perseus I is due to its fairly low surface brightness ($\mu _0=25.7^{+1.0}_{-0.9}$ mag arcsec–2), and to the previous lack of deep, high quality photometric data in this region. If confirmed to be a companion of M31, the location of Perseus I, far east from its host, could place interesting constraints on the bulk motion of the satellite system of M31.en-USgalaxies: individual (Perseus I, Andromeda XXXIII)Local GroupJournal Article2017-05-1620132017-07-1810.1088/2041-8205/779/1/L10