HEAD 2000, November 2000
Session 5. Blazars
Display, Monday, November 6, 2000, 8:00am-6:00pm, Bora Bora Ballroom

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[5.09] The Rapid Variability of BL Lac

H.R. Miller, E.C. Ferrara (Georgia State University), J.C. Noble (Boston University), J.P. McFarland, A.M. Williams (Georgia State University)

A substantial change in the character of the variability of BL Lacertae was observed near the beginning of the 1997 observing season. The source was observed to undergo a major outburst of more than 3-mag beginning in May, 1997. This outburst is known to have been accompanied by at least one major gamma-ray event observed by EGRET. The source has remained at this elevated level for most of the past three years. Superposed on this major outburst were many extremely rapid variations which have amplitudes of 0.1-1.0 mag. and durations spanning timescales of less than one hour to several days. The results of our monitoring of this source, both prior to the 1997 outburst and following this outburst, will be presented and the nature of the variations discussed. Implications of these variations for the source structure and physical emission processes will also be discussed.



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