Wednesday February 19 at 3:30pm

Svetlana Marchenko, St. Petersburg State University, & Alan Marscher, Boston University

``Variations of the Spectrum and Polarization of the BL Lac Object OJ287 during Major Outbursts''

ABSTRACT: "Dr. Marchenko will discuss the variations in the IR-optical-uv spectrum of OJ 287 during the past two major outbursts (1994 and 1982). The spectrum flattened at higher flux levels during the stronger of the two events. It is possible that the source became synchrotron-self-absorbed during the stronger flare. Dr. Marscher will use changes in the polarization and the absence of a radio counterpart for the 1994 outburst to associate it with an increase in the luminosity at the base of the jet. A secondary flare that occurred in late 1995 is interpreted as a shock that forms when the new, more energetic flow reaches the radio emitting portion of the jet."