A Week-long Multiwavelength Campaign to Monitor the Flaring Activity of Sgr A*

F.K. Baganoff1, M. Morris2, M.W. Bautz1, E.E. Becklin2, W.N. Brandt3, G. Chartas3, A.S. Cotera4, A. Eckart5, E.D. Feigelson3, G.P. Garmire3, R. Genzel6, A.M. Ghez2, R.M. Herrnstein7, P.M. Hinz4, W.F. Hoffmann4, J.L. Hora7, S.D. Hornstein2, J.-P. Macquart8, Y. Maeda9, M.R. Meyer4, G.R. Ricker1, R.J. Sault10, A.M. Tanner2, G.B. Taylor11, F. Walter12, J.-H. Zhao7

1 Center for Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
2 Department of Physics and Astronomy, University of California at Los Angeles, Los Angeles, CA 90095, USA
3 Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802, USA
4 Steward Observatory, University of Arizona, Tucson, AZ 85721, USA
5 I. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany
6 Max-Planck-Institut für Extraterrestrische Physik, D-85740 Garching bei München, Germany
7 Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA
8 Kapteyn Institute, University of Groningen, Postbus 800, Groningen 9700 AV, Netherlands
9 Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, 229-8501, Japan
10 Australia Telescope National Facility, P.O. Box 76, Epping, NSW 1710, Australia
11 National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801, USA
12 Department of Astronomy, California Institute of Technology, Pasadena, CA 91125, USA

E-mail contact: fkb@space.mit.edu

Spurred by the discovery of rapid and intense X-ray flaring of Sgr A* in October 2000 with the Chandra X-Ray Observatory, we have performed a week-long campaign to monitor Sgr A* simultaneously in the X-ray, infrared, millimeter, and radio wavebands. Between 22 May 2002 and 4 June 2002, the ACIS-I instrument on Chandra observed a field centered on Sgr A* for a total of 0.5 Ms. During this time, a network of ground-based telescopes were employed for simultaneous observations for varying amounts of time and at various wavelengths: the Keck-I Telescope at 2 and 10 microns; the VLT at 2 to 5 microns; the Magellan-Baade Telescope at 10 microns; the SMA at 1 mm; the ATCA and the Owens Valley Millimeter Array at 3 mm; the VLBA at 7 mm; and the VLA at 0.7, 1.3 and 2 cm. Models for the X-ray flares from Sgr A* can in principle be distinguished and assessed on the basis of their predictions for the correlated emission variations at (sub)millimeter, radio, and infrared wavelengths. We report on hour-time-scale X-ray variability during this campaign, and present the results at all other wavelengths observed in coincidence with the X-ray activity. The duty cycle and the beginnings for the luminosity function of X-ray flares are described. The competing models are assessed in the context of these results.