2008AJ....135.1384G

We selected a sample of a dozen blazars which are the prime candidates for simultaneous multi-wavelength observing campaigns in their outburst phase. We searched for optical outbursts, intra-day variability (IDV) and short-term variability in these blazars. We carried out optical photometric monitoring of nine of these blazars in 13 observing nights during our observing run of 2006 October 27-2007 March 20 using the 1.02 m optical telescope equipped with CCD detector and BVRI Johnson broadband filters at Yunnan Astronomical Observatory, Kunming, China. From our observations, our data favor the hypothesis that three blazars, AO 0235+164, S5 0716+714, and 3C 279, were in the outburst state; one blazar, 3C 454.3, was in the post-outburst state; three blazars, S2 0109+224, PKS 0735+178, and OJ 287, were in the pre/post-outburst state; one blazar, ON 231, was in the low state; and the state of one blazar, 1ES 2344+514, was not known because there are not many optical data available for the blazar to compare with our observations. We observed densely sampled 1534 image frames of these nine blazars. Out of three nights of observations of AO 0235+164, IDV was detected in two nights. Out of five nights of observations of S5 0716+714, IDV was detected in two nights. In one night of observations of PKS 0735+178, IDV was detected. Out of six nights of observations of 3C 454.3, IDV was detected in three nights. No IDV was detected in S2 0109+224, OJ 287, ON 231, 3C 279, and 1ES 2344+514 in their one, four, one, two, and one nights of observations, respectively. AO 0235+164, S5 0716+714, OJ 287, 3C 279, and 3C 454.3 were observed in more than one night and short-term variations in all these blazars were also noticed. From our observations and the available data, we found that the predicted optical outbursts with time intervals of ∼8 years in AO 0235+164 and ∼3 years in S5 0716+714 have possibly occurred.