4 Conclusions

We have presented results of the Tuorla Optical Quasar Monitoring program from two observing seasons, from autumn 1995 to spring 1997. Our observations have shown that some blazars might have quite large flux variations in timescales of a few days, the best example being CTA 102. We found some indications for possible periodicity on a timescale of 60- 70 days in S5 0716+714 (not yet confirmed) and in 3C 66A (see Lainela et al. 1999) and observed the second peak of the predicted outburst in OJ 287. We measured one of the brightest V-band values ever for S2 0109+224, 3C 66A, and ON 231 and one of the faintest V-band values ever for OI 090.4.

Considering our sample of BL Lacs, HPQs, and LPQs we can say, as a conclusion, that those few LPQs, which were selected to our sample, did not show as large optical variations as BL Lacs or HPQs. No difference between BL Lacs and HPQs can be seen. Despite the large amount of collected data, we must still say that more data is needed to get better understanding of the behaviour of these highly variable objects. Only long term monitoring of these blazars and quasars can show if the observed brightness variations are totally sporadic or not. The best examples of possible non-sporadic variations are blazars OJ 287 and 3C 66 A. This emphasizes also the importance of collaboration between observatories which have similar monitoring programs.

Acknowledgements

This work was partly supported by the Academy of Finland.