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We present the discovery of two new dwarf galaxies, Andromeda XXI andAndromeda XXII, located in the surroundings of the Andromeda and Triangulumgalaxies (M31 and M33). These discoveries stem from the first year data of thePan-Andromeda Archaeological Survey (PAndAS), a photometric survey of theM31/M33 group conducted with the Megaprime/MegaCam wide-field camera mounted onthe Canada-France-Hawaii Telescope. Both satellites appear as spatialoverdensities of stars which, when plotted in a color-magnitude diagram, followmetal-poor, [Fe/H]=-1.8, red giant branches at the distance of M31/M33.Andromeda XXI is a moderately bright dwarf galaxy (M_V=-9.9+/-0.6), albeit withlow surface brightness, emphasizing again that many relatively luminous M31satellites still remain to be discovered. It is also a large satellite, with ahalf-light radius close to 1 kpc, making it the fourth largest Local Groupdwarf spheroidal galaxy after the recently discovered Andromeda XIX, AndromedaII and Sagittarius around the Milky Way, and supports the trend that M31satellites are larger than their Milky Way counterparts. Andromeda XXII is muchfainter (M_V=-6.5+/-0.8) and lies a lot closer in projection to M33 than itdoes to M31 (42 vs. 224 kpc), suggesting that it could be the first Triangulumsatellite to be discovered. Although this is a very exciting possibility in thecontext of a past interaction of M33 with M31 and the fate of its satellitesystem, a confirmation will have to await a good distance estimate to confirmits physical proximity to M33. Along with the dwarf galaxies found in previoussurveys of the M31 surroundings, these two new satellites bring the number ofdwarf spheroidal galaxies in this region to 20.

PAndAS' cubs: discovery of two new dwarf galaxies in the surroundings of the Andromeda and Triangulum galaxies