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Session 36 - Active Galactic Nuclei.
Display session, Tuesday, June 09
Atlas Ballroom,
We present observations of the BL Lacertae object Markarian 501 made in 1997 and 1998 at E>300 GeV with the Whipple 10 m \gamma-ray telescope as well as contemporaneous observations made in the optical, UV, and X-ray wavebands. The data taken in 1997 show strong evidence for correlated variability in the very high energy \gamma-ray data and data taken from the Oriented Scintillation Spectrometer Experiment (OSSE) of the Compton Gamma Ray Observatory, as well as data taken with the Rossi X-Ray Timing Explorer (RXTE). These data were remarkable since they suggested that the synchrotron emission of the source extended to energies of at least 100 keV, the highest synchrotron energy every recorded for a Blazar. Short-term optical correlations were not conclusive, but the variations in the U-band flux obtained with the 1.2 m telescope of the Whipple Observatory indicated a possible correlation as well. In addition to presenting more detailed results from the 1997 observing season, we will also present results of recent multiwavelength observations to be made in May 1998 including scheduled observations with RXTE, OSSE and Whipple. Implications of these data on the Doppler factor of the jet, the magnetic field in the emission region, and the radiation mechanism responsible for the \gamma-ray emission will be discussed.
