OJ-94 project: Preliminary analysis of light curves of OJ 287 and 3C 66A

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Session 110 -- Blazars and BL Lacs
Display presentation, Thursday, 12, 1995, 9:20am - 6:30pm

[110.02] OJ-94 project: Preliminary analysis of light curves of OJ 287 and 3C 66A

Harry J Lehto (Tuorla Observatory, Piikki\"o, Finland), Paul Boltwood (Stittsville, Ontario, Canada)

Preliminary analysis is presented of the data obtained by the OJ-94 international multiwavelength project. The V-band light curve of OJ~287 for the 1993/94 season contains over 1400 data points contributed by 40~observers in 8~different countries (Sadun et al.\ (this meeting) and Kidger et al (this meeting)). The V-band light curve of 3C66A has over 400 data points (Takalo et al.\ (this meeting)). The light curves have good coverage on time scales from 1~day to 200~days and locally good coverage from 5~minutes to 16~hours. In OJ~287 no global time lags larger than 2~days have been detected between the B,V,R and I light curves binned to 1~day bins. The power spectra of both sources appear divergent, with most of the variability on time scales longer than about a week. Both correlation and power spectral analysis measure global properties and are unfortunately completely insensitive to local changes in the behavior of the light curve.

To find changes in the local behavior of the light curve we made linear fits of various lengths to all parts of the data. OJ~287 exhibits high periods of activity with variability time scales as short as 1-2 days for a one magnitude change. The time of activity coincides with the flares, which typically last for a week. Between flares the timescale of variability is 1-2 orders of magnitude longer. Fast variability is also present in 3C66A but the periods of high activity are less well defined.

In September and October 1994, the behavior of OJ~287 appears to have changed into a rapid brightening. An update of behavior of OJ~287 and 3C66A will be given.

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