The Quasar 3C 345 reaches a high state of brightness also in the optical range

ATel #15341; Jonas Seufert, Elias Ankara, Tim Apell, Niels Bader, Linus Bertsch, Karim Heidemann, Felix Hemrich, Ben Horst, David Kuberek, Alexander Lessing, Jonas Ludwig, Korbinian Rosenlehner, Lukas Waller, David Reinhart, Nils Zottmann, Martin Feige, Christian Lorey (all Friedrich-Koenig-Gymnasium / Hans-Haffner-Sternwarte), Karl Mannheim (Universitaet Wuerzburg), Dominik Elsaesser (TU Dortmund)
on 21 Apr 2022; 08:38 UT
Credential Certification: Dominik Elsaesser (dominik.elsaesser@tu-dortmund.de)

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In early April 2022, the flat-spectrum radio quasar 3C 345 (ICRS coords. (ep=J2000): RA 16 42 58.8103 DEC +39 48 37.0027) displayed increased activity in the gamma and X-ray range;
On April 4, Fermi LAT observed high gamma-ray activity in the region of radio quasar 3C 345 (ATel #15313). AGILE-GRID also detected increased gamma-ray activity in this region from April 3 to 6 (ATel #15314). In the following days, an intensified X-ray flux was measured by Swift (ATel #15328).

Now, approximately 2 weeks later, we detected a significant increase of the optical brightness of this source in the R-band from 16.536mag to 15.979mag in the period from April 17 to April 21.

We report the following R-band magnitudes:

JD 2459686.5204: 16.536 ± 0.029
JD 2459687.5693: 16.364 ± 0.020
JD 2459689.4761: 16.077 ± 0.015
JD 2459689.5076: 16.081 ± 0.014
JD 2459689.5739: 16.098 ± 0.014
JD 2459690.3821: 15.979 ± 0.015
JD 2459690.4211: 16.036 ± 0.012
JD 2459690.4778: 16.017 ± 0.027
JD 2459690.6058: 16.020 ± 0.029

This optical activity is comparable to the one that was detected earlier this year (ATel #15244), and close to that measured in 2018 (ATel #11624).

Due to the weather conditions, we were only able to conduct one measurement during the period in which the detections were made in the gamma and X-ray range: JD 2459681.6234: 16.655 ± 0.043.


These measurements were 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 the TU Dortmund University with the 0.5m CDK astrograph and Bessel filters at the school and university observatory Hans-Haffner-Sternwarte in D-97265 Hettstadt (Germany).

AGN Monitoring Program at the Hans-Haffner-Sternwarte in Hettstadt