Recent optical activity of the blazar B2 1811+31

ATel #14103; Giacomo Bonnoli, Edoardo Bucalo, Alessandro Marchini, Leonardo Stiaccini (Astronomical Observatory, Department of Physical Sciences, Earth and Environment, University of Siena), Lukas Waller, Felix Hemrich, Ben Horst, David Reinhart, Korbinian Rosenlehner, Kilian Schoch, Dirk Seifert, Remco Steineke, Lukas Kunkel (Hans-Haffner-Sternwarte / Friedrich-Koenig-Gymnasium), Christian Lorey, Martin Feige (Hans-Haffner-Sternwarte / Friedrich-Koenig-Gymnasium), Karl Mannheim (Universitaet Wuerzburg), Dominik Elsaesser (TU Dortmund), Elisa Prandini (Department of Physics and Astronomy, University of Padova and INFN Padova), Vandad Fallah Ramazani (Finnish centre for astronomy with ESO, University of Turku)
on 18 Oct 2020; 11:32 UT
Credential Certification: Giacomo Bonnoli (giacomo.bonnoli@unisi.it)

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B2 1811+31 (R.A.=18 13 35.2027 Dec.=+31 44 17.620, J2000.0) is a BL Lac object at a redshift of z=0.117 (Giommi et al. 1991, ApJ, 378, 77) that has recently been detected as flaring in the high-energy and very-high-energy gamma-ray bands by the Fermi-LAT and MAGIC Collaborations respectively (ATels #14060,#14090).

Here, the AGN monitoring group at the Naturwissenschaftliches Labor fuer Schueler am Friedrich-Koenig-Gymnasium (FKG) and at the Astronomical Observatory of the University of Siena (Italy) report on the recent optical R-band activity of the source to provide multi-wavelength context and encourage further observation efforts also in other bands. Field calibration was provided by the Tuorla Blazar monitoring program publicly available at the web address https://users.utu.fi/kani/1m/index.html.

Civil Date (UT) Rmag(dRmag) Observatory Notes.

2020 Oct 03.80 15.11(0.01)   Hettstadt
2020 Oct 03.85 15.12(0.01)   Hettstadt
2020 Oct 05.78 15.23(0.02)   Siena
2020 Oct 06.83 15.24(0.01)   Hettstadt
2020 Oct 07.77 15.20(0.01)   Hettstadt
2020 Oct 07.85 15.18(0.01)   Hettstadt
2020 Oct 10.75 15.16(0.01)   Hettstadt
2020 Oct 10.82 15.17(0.01)   Hettstadt
2020 Oct 11.75 15.02(0.01)   Hettstadt
2020 Oct 11.85 15.07(0.01)   Hettstadt
2020 Oct 12.75 15.15(0.01)   Hettstadt
2020 Oct 12.83 15.15(0.01)   Hettstadt
2020 Oct 13.79 14.66(0.08)   Siena      Poor sky conditions
2020 Oct 13.87 15.08(0.02)   Hettstadt
2020 Oct 16.81 15.17(0.04)   Siena


Quoted uncertainty is statistical only. We will continue monitoring the source in the following nights.

These measurements are carried out as part of the long-term AGN monitoring program of the Naturwissenschaftliches Labor fuer Schueler am Friedrich-Koenig-Gymnasium (FKG), the Universitaet Wuerzburg, and TU Dortmund with the 0.5m telescope at the school and university observatory Hans-Haffner-Sternwarte in Hettstadt (Germany), and as part of the long-term AGN monitoring program of the Astronomical Observatory of the University of Siena (Italy) with the 0.3m telescope at the Observatory site in Siena. The observatories and programs are reachable on the web at the addresses https://schuelerlabor-wuerzburg.de/sternwarte/ and https://www.dsfta.unisi.it/en/research/labs/astronomical-observatory respectively. We encourage contact to the teams in case coordinated observations are desired.