In the broad class of extragalactic objects known as AGN, blazars distinguish themselves in many ways. The most extreme and unique property of blazars is their highly beamed continuum, most likely produced by a jet of relativistic material aimed close to the observer's line of sight. Blazars may be classified as X-ray and radio selected blazars (XBLs and RBLs) based on their spectral properties. The results for four new multiwavelength campaigns are reported; two for XBLs and two for RBLs. Each campaign contains simultaneous observations in the radio, optical, and X-ray regimes. A campaign on a third RBL was completed using near-simultaneous archival radio, optical/IR, and EGRET data. The simultaneous multiwavelength behavior is analyzed by examining the multiwavelength variability and using spectral analysis. Observations of prominent optical microvariabiltiy is quantitatively analyzed. Previously published results for other blazars are compared to the new and archival results.
The campaigns on PG 1553+11, CTA 102, and PKS 1622-297 were the first simultaneous multiwavelength campaigns performed for these objects. PG 1553+11, a radio-weak blazar, was found to be an extreme XBL. PKS 2155-304, a frequently studied XBL, appears to exhibit different variability behavior during different epochs. Furthermore, flares in different wavebands appeared to have smaller time lags and similar structure as the flux state increased. For objects in which the results of at least two campaigns were available, including PKS 2155-304, correlations that appear at one epoch may vanish at other times. In all cases, the SSC model serves to represent the observations well. The RBLs all exhibited large amplitude optical microvariability. CTA 102, an RBL, exhibited some of the most extreme optical microvariability ever observed. Surprisingly, the optical spectra of RBLs CTA 102 and PKS 1622-297 were found to become redder when in a brighter flux state. Color studies of the selected BL Lac objects found them to be bluer when brighter, while the selected FSRQs were found to be redder when brighter.