Increase of the optical brightness of 3C 371 observed at the Hans-Haffner-Sternwarte

ATel #15761; B. Horst, E. Ankara, N. Bader, L. Bertsch, F. Hemrich, D. Kuberek, A. Lessing, B. Mengelkamp, K. Rosenlehner, D. Scheuermayer, J. Seufert, R. Steineke, D. Reinhart, N. Zottmann, M. Feige, C. Lorey (all Friedrich-Koenig-Gymnasium / Hans-Haffner-Sternwarte), K. Mannheim (Universitaet Wuerzburg), D. Elsaesser (TU Dortmund)
on 14 Nov 2022; 15:31 UT
Credential Certification: Dominik Elsaesser (dominik.elsaesser@tu-dortmund.de)

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During the last two weeks we could observe an increase of the optical activity of the BL Lac-type object 3C 371 (RA: 18 06 50.6802916920 Dec: +69 49 28.109609256; ICRS J2000; z= 0,051) in the R-band. In the weeks before, the brightness of this object fluctuated around 14.4 mag and then slowly increased. The brightness increased then from 14.35 mag to 13.94 mag. This is the highest value we have measured since we started monitoring this object in October 2020.
The brightest this blazar has been within the last 15 years was probably in the night of 2018 April 22 with R=13.35 (ATel #11563).


We report the following preliminary R-band magnitudes:
JD 2459844.4669: 14.543 (0.008)
JD 2459852.3303: 14.437 (0.009)
JD 2459853.3187: 14.447 (0.008)
JD 2459855.4544: 14.447 (0.009)
JD 2459856.5306: 14.489 (0.012)
JD 2459858.2711: 14.350 (0.022)
JD 2459861.3961: 14.343 (0.014)
JD 2459865.3993: 14.403 (0.030)
JD 2459869.4488: 14.348 (0.010)
JD 2459872.4049: 14.321 (0.010)
JD 2459879.3756: 14.353 (0.011)
JD 2459883.2459: 14.249 (0.013)
JD 2459885.4817: 14.176 (0.011)
JD 2459886.4664: 14.187 (0.083) (foggy night!)
JD 2459897.2995: 13.947 (0.008)
JD 2459897.3093: 13.965 (0.008)
JD 2459897.3269: 13.948 (0.009)
JD 2459897.3393: 13.936 (0.009)
JD 2459897.3597: 13.938 (0.010)
JD 2459897.3696: 13.944 (0.010)
JD 2459897.3818: 13.944 (0.010)


Due to the weather situation, we will probably not be able to continue monitoring this object during the next nights. So we propose a further surveillance by other observatories.

The observations were conducted within the framework of the WEBT Collaboration (https://www.oato.inaf.it/blazars/webt/) and carried out as part of the long-term AGN monitoring program of the Naturwissenschaftliches Labor fuer Schueler am Friedrich-Koenig-Gymnasium (https://schuelerlabor-wuerzburg.de/en/), the Universitaet Wuerzburg, and the TU Dortmund.

Naturwissenschaftliches Labor fuer Schueler am Friedrich-Koenig-Gymnasium