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Astron. Astrophys. Suppl. Ser.
Volume 143, Number 3, May I 2000
Page(s) 357 - 368
DOI: 10.1051/aas:2000184

Astron. Astrophys. Suppl. Ser. 143, 357-368

Tuorla quasar monitoring[*]

I. Observations of 1995-1997

S. Katajainen1 - L.O. Takalo1 - A. Sillanpää1 - K. Nilsson1 - T. Pursimo1 - M. Hanski1 - P. Heinämäki1 - E. Kotoneva1 - M. Lainela1 - P. Nurmi1 - H. Pietilä1 - R. Rekola1 - A. Riehokainen1 - P. Teerikorpi1 - E. Valtaoja1,2 - A. Lähteenmäki2

Send offprint request: S. Katajainen,

1 - Tuorla Observatory, Väisäläntie 20, FIN-21500 Piikkiö, Finland
2 - Metsähovi Radio Observatory, Helsinki University of Technology, FIN-02540 Kylmälä, Finland

Received March 30; accepted November 26, 1999


We present results of optical monitoring of quasars and blazars obtained at Tuorla Observatory between September 1995 and May 1997. The aim of our monitoring is to provide well sampled optical light curves for quasar and blazar studies. During the observing period the V-band brightness of S2 0109+224, 3C 66A, and ON 231 (W Comae) reached some of the brightest values ever measured for these objects. A strong outburst was observed in Mrk 421 and the large outburst, which was predicted earlier, in OJ 287 was confirmed. CTA 102 had over one magnitude outburst which happened in a timescale of a few days. For OI 090.4 we measured one of the faintest V-band brightness values ever.

Key words: galaxies: active -- BL Lacertae objects: general -- quasars: general

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