Rapid optical variability of gamma-raye-loud blazars

We present the optical (B, V, and R) photometry for nine GeV and/or TeV gamma -ray blazars, which were observed from 2000 through 2001 with the 1 m telescope at Yunnan Astronomical Observatory. The GeV gamma -ray-loud source PKS 1510-089 was very active during our observation period, showing an apparent variation of 2.0 mag within 41 minutes in the R band. This is the most violently rapid variability in our optical monitoring program since 1982. Some physics parameters are calculated for this source, namely, the emission size, Doppler factor delta, the efficiency (eta) for conversion of accreted matter into energy, and luminosity. An eta = 62.2 was obtained, strongly implying that relativistic beaming is responsible for the rapid variability of the gamma -ray-loud source. The influence of variable seeing conditions on the observations was investigated. There is a weak correlation between the observed variability and the local seeing conditions for the object 1ES 2344+51.4.