Multiwavelength Observations of 1ES 1959+650, 1 Year after the Strong Outburst of 2002

Abstract

In 2003 April-May, the blazar IES 1959+650 showed an increased level of X-ray activity. This prompted a multiwavelength observation campaign with the Whipple 10 m γ-ray telescope, the Rossi X-Ray Timing Explorer, the Bordeaux Optical Observatory, and the University of Michigan Radio Astronomy Observatory. We present the multiwavelength data taken from 2003 May 2 to June 7 and compare the source characteristics with those measured during observations taken during the years 2000 and 2002. The X-ray observations gave a data set with high signal-to-noise ratio light curves and energy spectra; however, the γ-ray observations did not reveal a major TeV γ-ray flare. Furthermore, we find that the radio and optical fluxes do not show statistically significant deviations from those measured during the 2002 flaring periods. While the X-ray flux and X-ray photon index appear correlated during sub-sequent observations, the apparent correlation evolved significantly among the years 2000, 2002, and 2003. We discuss the implications of this finding for the mechanism that causes the flaring activity. © 2006. The American Astronomical Society. All rights reserved.