Coordinated observations of OJ 287 at radio and optical wavelengths

Abstract

Observations of the total flux of OJ 287 were made at 11.1, 4.5, 3.7, 2.8, 0.95, and 0.35 em and at 0.44 ;i during early 1972 when the object had its greatest recorded optical brightness. The linear polarization was measured at 3.7 and 11.1 em and at 0.4 . Significant changes in the total flux in times of the order of a day were found at 4.5 em and shorter wavelengths. These rapid fluctuations at short centimeter wavelengths were in phase to within a small fraction of a day. No correlation was seen between the optical and radio fluctuations. Linear polarization was found at both radio and optical wavelengths which varied with the same time scales as the total flux. At all observed wavelengths, the position angle tended to show sudden excursions from an otherwise smooth trend. Correlograms of the optical total flux and Stokes parameters give evidence for an eight day periodicity. The consequences of these observations (which do not fit in with the usual expanding cloud model) are briefly discussed.