CGRO Observations of BL Lac Objects and Other Blazars

Among the roughly 60 blazars detected by EGRET, about a quarter are classified as BL Lac objects. Although most are of the RBL subspecies, a small number of XBLs have now been detected. In general, the BL Lacs appear to have slightly harder spectra than the other blazars. One BL Lac object, BL Lacertae itself, received exceptionally good optical coverage during an EGRET target-of-opportunity flare observation in 1997 July. During a 1-day miniflare in the middle of the EGRET observation, the optical and gamma-ray fluxes appeared to peak very close in time, with the gamma rays possibly peaking a few hours earlier than optical flux. In the only other blazar flare with comparable coverage, that of 3C 279 in 1996 Feb, there is little evidence for 1-day-scale gamma/optical correlation, although both were bright. Other gamma-ray characteristics of BL Lac objects, and comparisons with flat-spectrum radio quasars detected by EGRET, will be presented.