The Multiple Timescales of Optical Variability of the Blazar 3C 279 during the 2001-2002 Outburst

Abstract

During 2001-2002 the optically violent variable blazar 3C 279 underwent the most intense outburst seen during the entire 14 yr period that this quasar has been studied at Colgate University's Foggy Bottom Observatory. This study concentrates on ~1600 R-filter images taken during this period of activity. This data set includes 29 nights of microvariability coverage. The outburst began in 2001 March, after 3C 279 had faded to its faintest level, R = 15.5, in 4 yr. The source reached its brightest level, R = 12.5, in the 14 yr of our study in 2001 August, at which time it became unobservable due to its proximity to the Sun. On becoming observable again in 2001 mid-December, 3C 279 fluctuated between R = 13.9 and 14.7, until a dramatic decrease in flux level in 2002 June-July brought the source back down to a level comparable to its preoutburst state. The source exhibited numerous week-long flares of approximately 1 mag during the outburst period. Superposed on these flares were night-to-night variations of up to 0.5 mag and intranight microvariability of up to 0.13 mag in 3 hr. We use visual inspection of the light curve, as well as numerical timescale analysis tools (the autocorrelation function, the structure function, and the power spectrum), to characterize the multiple timescales of variability ranging from 1.5 yr to several hours.