Photographic studies of quasi-stellar objects and other active radio sources

Studies of the optical variability of a sample of 14 quasars and similar objects at Rosemary Hill Observatory detected statistically significant fluctuations in the light curves of PKS 0048-09, PKS 0420-01, PKS 0735+17, PKS 0736+01, PKS 0906-01, PKS 1510-08, and PKS 2349-01. Apparent color variations observed in a sample of QSO's at Rosemary Hill appear to be generally compatible with the expanding source model. However, 0J 287 and 3C 345 appear to be exceptions, as variations in their color indices suggest that changes in the slope of the optical spectrum may not be simply correlated with brightness. A spectral model composed of thermal and non-thermal components is offered as a possible explanation for the color variations observed in the objects studied. Studies of the lacertids PKS 1514-24, ON 231, and ON 325 suggest that the optical behavior of PKS 1514-24 and ON 231 is similar to that of the prototype lacertid BL Lac, while ON 325 shows more moderate short-term optical behavior superimposed on long-term fluctuations of several months' duration. A search for intraday activity in BL Lac detected statistically significant variations on two nights; the largest such variation was a decline of 0.6 m in 33 minutes. A search for an Io-related Jovian auroral hotspot has ended with essentially negative results. During the 1973 Jovian apparition, a total of 160 Jovian images was taken at Rosemary Hill in low-albedo ultraviolet and infrared regions. Visual examination and computer reductions revealed no trace of the hotspot