The quasar TON 0599 reaches a new optical maximum

ATel #14775; Adrian Scherbantin, Lukas Kunkel, Karl Mannheim (all Universitaet Wuerzburg), Niels Bader, Erik Heidemann, Karim Heidemann, Felix Hemrich, Ben Horst, Kai Koeberlein, Felix Molz, David Reinhart, Korbinian Rosenlehner, Kilian Schoch, Remco Steineke, Dirk Seifert, Lukas Waller, Nils Zottmann, Martin Feige, Christian Lorey (all Friedrich-Koenig-Gymnasium / Hans-Haffner-Sternwarte), Dominik Elsaesser (TU Dortmund)
on 12 Jul 2021; 16:55 UT
Credential Certification: Dominik Elsaesser (dominik.elsaesser@tu-dortmund.de)

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Since January of this year, the flat-spectrum radio quasar Ton 0599 (4C 29.45, PKS 1156+295; ICRS coords. (ep=J2000): RA 11 59 31.834 Dec +29 14 43.827 z=0.7) has been showing strong activity in both the optical (ATel # 14353; # 14391; # 14547; # 14696) and gamma-ray (ATel # 14722) spectral regions. After a high magnitude of 13.91 on April 10, 2021 (JD = 2459314.4999), a very high magnitude in the R band of 13.70 was published for June 17, 2021 (ATel # 14727). Last night (JD 2459407.4356) we were now able to measure a value of 13.516 (+/-0.007) in R-band, which is quite exceptional for this object.
After flares in mid-April 2012 (ATel # 4051) and early May 2015 (ATel # 7474), each with a brightness of 15.1 mag, and of 14.22 (ATel # 10948) and 14.03 (ATel # 10949) in November 2017, the highest brightness to date of 15 to 13 mag (R-band, fractional magnitude values not specified) was then reached in May 2018 (ATel # 11624).
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 observation by other observatories.

Here are the values of the last nights of TON 0599:

R - band magnitudes:

JD 2459367.4690: 15.806 ± 0.010
JD 2459377.4543: 14.753 ± 0.009
JD 2459378.4309: 14.697 ± 0.014
JD 2459383.4228: 14.013 ± 0.008
JD 2459401.4435: 13.692 ± 0.006
JD 2459403.4059: 13.718 ± 0.005
JD 2459406.3712: 13.872 ± 0.020
JD 2459407.4356: 13.516 ± 0.007

V - band magnitudes:

JD 2459367.4735: 16.301 ± 0.014
JD 2459377.4589: 15.192 ± 0.013
JD 2459378.4356: 15.163 ± 0.016
JD 2459383.4183: 14.439 ± 0.009
JD 2459401.4481: 14.087 ± 0.007
JD 2459403.4105: 14.106 ± 0.006
JD 2459406.3758: 14.304 ± 0.014
JD 2459407.4402: 13.937 ± 0.009

B - band magnitudes:

JD 2459367.4781: 16.865 ± 0.019
JD 2459377.4636: 15.776 ± 0.023
JD 2459378.4403: 15.681 ± 0.020
JD 2459383.4137: 14.925 ± 0.014
JD 2459401.4527: 14.650 ± 0.012
JD 2459403.4150: 14.635 ± 0.010
JD 2459406.3804: 14.800 ± 0.057
JD 2459407.4450: 14.503 ± 0.015


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).

Monitoring Programm Website