The Blazar TON 0599 is now in a particularly bright state in the optical as well

ATel #15870; A. Scherbantin, K. Mannheim (all Universitaet Wuerzburg), E. Ankara, N. Bader, L. Bertsch, M. Daig, O. Domann, K. Heidemann, M. Heidemann, F. Hemrich, B. Horst, F. Kees, L. Kimmel, D. Kuberek, R. Steineke, L. Waller, D. Reinhart, N. Zottmann, M. Feige, C. Lorey (all Friedrich-Koenig-Gymnasium / Hans-Haffner-Sternwarte), D. Elsaesser (TU Dortmund)
on 21 Jan 2023; 12:00 UT
Credential Certification: Dominik Elsaesser (dominik.elsaesser@tu-dortmund.de)

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Since mid-January, the flat-spectrum radio quasar Ton 0599 (4C 29.45, PKS 1156+295; ICRS coordinates (ep=J2000): RA 11 59 31.834 DEC +29 14 43.827, z=0.7) has been showing strong activity in both the x-ray (ATel # 15854) and gamma-ray (ATel #15853; #15859) spectral bands.
While this object displayed optical brightness values in the range between 15.5 and 14.2 mag (R-band) in the last quarter of last year, we were able to measure a peak brightness of 13.373 mag in the R-band in the night from 18 January 2023 to 19 January 2023.
Such brightness values in the optical regime are comparable to the strong outbursts of June 2022 (R-band: 13.39 mag; ATel #15441) and January to July 2021 (R-band 14.9 to 13.5 mag; ATel #14353; #14391; #14547; #14696; #14727; #14775), and earlier flares in 2012 (ATel # 4051), 2015 (ATel # 7474), 2017 (ATel # 10948; # 10949) and 2018 (ATel # 11624).


Here we report the following values of TON 0599 in the R-Band:

JD 2459963.6294: 13.382 (0.016)
JD 2459963.6574: 13.373 (0.004)
JD 2459963.6713: 13.377 (0.004)
JD 2459965.6827: 13.634 (0.075)
JD 2459965.7213: 13.586 (0.007)
JD 2459965.7304: 13.556 (0.008)
JD 2459965.7556: 13.580 (0.015)


Due to the gloomy wintry weather, we were unfortunately unable to carry out higher cadence measurements of this object, and will probably not be able to do so in the next few days either. Therefore, we strongly recommend further measurements of this object.


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 at the school and university observatory Hans-Haffner-Sternwarte in D-97265 Hettstadt (Germany).

Naturwissenschaftliches Labor fuer Schueler am Friedrich-Koenig-Gymnasium