AN ORPHAN IN THE ‘‘FIELD OF STREAMS’’

We use Sloan Digital Sky Survey Data Release 5 photometry and spectroscopy to study a tidal stream that extends over50 in the north Galactic cap. From the analysis of the path of the stream and the colors and magnitudes of its stars, the stream is ~20þ75 kpc away at its nearest detection (the celestial equator). We detect a distance gradient: the stream is farther away from us at higher declination. The contents of the stream are made up from a predominantly old andmetal-poor population that is similar to the globular clustersM13 andM92. The integrated absolute magnitude of the stream stars is estimated to be Mr 7:5. There is tentative evidence for a velocity signature, with the stream moving at40 km s1 at low declinations and+100 km s1 at high declinations. The stream lies on the same great circle as Complex A, a roughly linear association of H i high-velocity clouds stretching over30 on the sky, and as Ursa Major II, a recently discovered dwarf spheroidal galaxy. Lying close to the same great circle are a number of anomalous, young, and metal-poor globular clusters, including Palomar 1 and Ruprecht 106. Subject headinggs: galaxies: kinematics and dynamics — galaxies: structure — Local Group 1