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Very high optical activity of blazar OJ287

ATel #4057; S. Zola, D. Koziel-Wierzbowska, A. Kuzmicz (Astronomical Observatory, Jagiellonian University, Poland), M. Drozdz, M. Winiarski, W. Ogloza, G. Stachowski (Mt. Suhora Observatory, Pedagogical University, Poland), A. Liakos (University of Athens, Greece), J. Provencal (University of Delaware, USA)
on 20 Apr 2012; 19:30 UT
Credential Certification: Staszek Zola (szola@oa.uj.edu.pl)

Subjects: Optical, Blazar

OJ287 is being monitored in the optical waveband with small telescopes at the Astronomical Observatory of the Jagiellonian University (KRK) and the Mt. Suhora Observatory of the Pedagogical University (SUH) in Poland, and at the University of Athens, Greece (ATH). On April 19th, Mt. Cuba Observatory, USA (MTC), performed additional observations of this target. We report an even higher optical state of OJ287 than that published in Atel #4020 and Atel #4021. CCD observations taken from April 17th - April 19th revealed that OJ287 has brightened by about 0.5 magnitude in the R filter from the level recorded at the beginning of April, reaching 13.4 mag. We used the comparison (#4) and check (#10) stars of known magnitude proposed by Fiorucci & Tosti (A&AS 116, 403, 1996) when reducing frames corrected for bias, dark and flatfield. The recently measured instrumental magnitudes in the R band are: (JDhel) 2456025.357445 14.12+-0.033 (ATH), 2456027.274415 13.89+-0.003 (SUH), 2456028.287525 13.88+-0.010 (KRK), 2456035.360795 13.52+-0.008 (KRK), 2456035.442950 13.45+-0.006 (SUH), 2456037.333320 13.40+-0.006 (SUH), 2456037.571545 13.52+-0.020 (MTC). The current brightness changes are rapid: on April 17th, we noted a rise in brightness by about 0.06 mag in two hours, while OJ287 faded by 0.12 mag in 5.5 hours on April 19th. This behavior seems to be consistent with flaring activity.