Name of the Speaker(s): H. Richard Miller
Institution: Dept. of Physics and Astronomy
Georgia State University
Atlanta, GA 30303
Title of the communication: THE CHARACTER OF MICROVARIABILITY FOR RADIO-SELECTED VERSUS X-RAY-SELECTED BL LAC OBJECTS
Preliminary abstract (12 lines max.): A sample of twenty-six blazars have been studied in an effort to investigate possible differences in the character of the optical variability exhibited by these objects on timescales ranging from minutes to hours. A comparison of the distribution of variability amplitudes for radio-selected BL Lacs (RBLs) with a similar distribution for the X-ray-selected BL Lacs (XBLs) demonstrates the presence of a large-amplitude component for the RBLs which is not detected for the XBLs. The distributions of variability amplitudes for the RBLs and XBLs were found to be extremely unlikely to have been drawn from the same parent population. Thus, the large-amplitude variations are probably unique to the RBLs. This is consistent with the picture proposed by Urry and Padovani (1995) that suggests that the RBLs are more narrowly beamed than are the XBLs.