The Effect of the Host Galaxy on the Short Timescale Variability of γ-ray Loud Blazars

We present the optical (V and R) photometry for three GeV and/or TeV γ-ray blazars,which were observed from 2000 through 2001,with the 1-m telescope at Yunnan Observatory.Through the observational period,the GeV γ-ray-loud source,PKS 1510-089,was very active and,it showed a significant variability of 2.0 mag within 41 min in the R band.This is the most violently rapid variability in our optical monitoring program for blazars since 1982. For this source,some physical parameters,namely the emission size,Doppler factor δ,the efficiency (η) for conversion of accreted matter into energy and luminosity are calculated. A η=59.6 was obtained,strongly implying that the relativistic beaming is responsible for the rapid variability of the γ-ray loud source.The influence of variable seeing conditions on the observations was carefully investigated.There is weak correlation between the observed variability and the local seeing conditions for the object 1ES 2344+514.The results show that the seeing fluctuations would influence the spurious variation in microvariability when the variability parameter C<5.