In The Astrophysical Journal, Volume 647, Issue 2, pp. L111-L114, 2006.

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V. Belokurov 1, D. B. Zucker 1, N. W. Evans 1, M. I. Wilkinson 1, M. J. Irwin 1, S. Hodgkin 1, D. M. Bramich 1, J. M. Irwin 1, G. Gilmore 1, B. Willman 2, S. Vidrih 1, H. J. Newberg 3, R. F. G. Wyse 4, M. Fellhauer 1, P. C. Hewett 1, N. Cole 3, E. F. Bell 5, T. C. Beers 6, C. M. Rockosi 7, B. Yanny 8, E. K. Grebel 9, D. P. Schneider 10, R. Lupton 11, J. C. Barentine 12, H. Brewington 12, J. Brinkmann 12, M. Harvanek 12, S. J. Kleinman 12, J. Krzesinski 12,13, D. Long 12, A. Nitta 12, J. A. Smith 14, S. A. Snedden 12

Abstract. In this Letter, we announce the discovery of a new satellite of the Milky Way in the constellation of Boötes at a distance of ~ 60 kpc. It was found in a systematic search for stellar overdensities in the North Galactic Cap using Sloan Digital Sky Survey Data Release 5 (SDSS DR5). The color-magnitude diagram shows a well-defined turn-off, red giant branch, and extended horizontal branch. Its absolute magnitude is MV ~ -5m.8, which makes it one of the faintest galaxies known. The half-light radius is ~ 220 pc. The isodensity contours are elongated and have an irregular shape, suggesting that Boo may be a disrupted dwarf spheroidal galaxy.

Keywords galaxies: dwarf -- galaxies: individual (Boötes) -- Local Group

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1 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK; vasily, zucker,
2 Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003
3 Rensselaer Polytechnic Institute, Troy, NY 12180
4 The Johns Hopkins University, 3701 San Martin Drive, Baltimore, MD 21218
5 Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
6 Department of Physics and Astronomy, CSCE: Center for the Study of Cosmic Evolution, and JINA: Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824
7 Lick Observatory, University of California, Santa Cruz, CA 95064
8 Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510
9 Astronomical Institute of the University of Basel, Department of Physics and Astronomy, Venusstrasse 7,CH-4102 Binningen, Switzerland
10 Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802
11 Princeton University Observatory, Peyton Hall, Princeton, NJ 08544
12 Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349
13 Mt. Suhora Observatory, Cracow Pedagogical University, ul. Podchorazych 2, 30-084 Cracow, Poland
14 Los Alamos National Laboratory, ISR-4, MS D448, Los Alamos, NM 87545