| Abstract | We report the detection of a faint old stellar system at (α, δ)=(194.29d, 34.32d) (SDSS J1257+3419), based on the spatial distribution of bright red giant branch stars in the Sloan Digital Sky Survey Data Release 4. SDSS J1257+3419 has a half-light radius of 38+/-12 pc and an absolute integrated V magnitude of MV=-4.8+1.4-1.0 mag at a heliocentric distance of 150+/-15 kpc. A comparison between SDSS J1257+3419 and known Galactic halo objects suggests that SDSS J1257+3419 is either (1) a faint and small dwarf galaxy or (2) a faint and widely extended globular cluster. In the former case, SDSS J1257+3419 could represent an entity of a postulated subhalo of the Milky Way. Further photometric and dynamical study of this stellar system is vital to distinguish these possibilities. |
