Sagittarius Tidal Debris 90 Kiloparsecs from the Galactic Center

A new overdensity of A-colored stars in distant parts of the Milky Way's stellar halo, at a dereddened SDSS magnitude of g₀ = 20. 3, is presented. Identification of associated variable RR Lyrae candidates supports the claim that these are blue horizontal branch stars. The inferred distance of these stars from the Galactic center is 90 kpc, assuming the absolute magnitude of these stars is Mg₀ = 0. 7 and that the Sun is 8. 5 kpc from the Galactic center. The new tidal debris is within 10 kpc of same plane as other confirmed tidal debris from the disruption of the Sagittarius dwarf galaxy, and could be associated with the trailing tidal arm. Distances to the Sagittarius stream estimated from M stars are about 13% smaller than our inferred distances. The tidal debris has a width of at least 10 degrees, and is traced for more than 20 degrees across the sky. The globular cluster NGC 2419 is located within the detected tidal debris, and may also have once been associated with the Sagittarius dwarf galaxy.