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E.J. McGrath (Vassar Coll.), T.J. Balonek (Colgate Univ.), T.J. Brandt (Vassar Coll.)
We present a ten year optical light curve for the blazar AO 0235+164 from 1989 through mid-1999. Observations were conducted at the Foggy Bottom Observatory at Colgate University using a sixteen inch Cassegrain telescope and CCD camera. Herein we note the correlations between optical and radio variations (radio observations obtained at the University of Michigan Radio Astronomy Observatory, UMRAO). MacLeod, Andrew, and Harvey (1976); Ledden, Aller, and Dent (1976); and Rieke et al. (1976) first noted a correlation between the optical and radio variations in a 1975 outburst of AO 0235+164. Balonek and Dent (1980) showed a second correlation in a 1979 outburst. Subsequent optical outbursts and further optical-radio correlations have been studied by several authors.
We study the long and short time scale variations in four additional optical outbursts in 1990, 1991, 1992, and 1998. We find that some of the bursts appear to be strongly correlated with radio bursts, while others do not exhibit simple correlations. Different physical phenomena may be needed in order to explain the differences in these outbursts. In the correlated cases, the optical burst appears to either nearly coincide with a radio burst, or precede a subsequent radio burst by a few months. The time scales of the outbursts agree with the generally accepted model of Blandford and Konigl (1979) of a relativistic shock propagating down a jet. In addition, intra-night variability is seen during these outbursts on much shorter time scales and is most likely caused by another phenomenon.
The author(s) of this abstract have provided an email address for comments about the abstract: tbalonek@mail.colgate.edu