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B2 1308+326 is dimming after the highest optical state

ATel #15496; M. Minev (Sofia University, Bulgaria), A. Valcheva (Sofia University, Bulgaria)
on 4 Jul 2022; 18:49 UT
Credential Certification: Antoniya Valcheva (valcheva@phys.uni-sofia.bg)

Subjects: Optical, Blazar, Quasar

Referred to by ATel #: 15515, 16360, 16964

During last week we perform optical monitoring of the flaring blazar B2 1308+326 (ICRS coords. (ep=J2000): RA 13 10 28.664 Dec +32 20 43.774). It is still in a high optical state (as reported in ATel #15441; ATel #15447; ATel #15459; ATel #15474; ATel #15476) with slightly decreasing flux (about 0.2-0.3 mag in R-band) measured on 2022 July 03.856 (JD 2459764.356). The maximum R-band magnitude we have measured is 12.61 ± 0.02 mag on 2022 July 01.859 UT (JD 2459762.361) - brighter than all previous records.

Here we report the following magnitudes:
B - band magnitudes:
2022 June 27.870 (JD 2459758.370)     13.60 ± 0.01 mag
2022 June 28.950 (JD 2459759.450)     13.56 ± 0.01 mag
2022 June 29.885 (JD 2459760.385)     13.55 ± 0.05 mag
2022 June 30.842 (JD 2459761.342)     13.48 ± 0.05 mag
2022 July 01.843 (JD 2459762.362)       13.32 ± 0.01 mag
V - band magnitudes:
2022 June 27.864 (JD 2459758.364)     13.27 ± 0.02 mag
2022 June 29.879 (JD 2459760.379)     13.17 ± 0.05 mag
2022 June 30.837 (JD 2459761.337)     13.11 ± 0.05 mag
2022 July 01.857 (JD 2459762.357)      12.99 ± 0.01 mag
R - band magnitudes:
2022 June 27.858 (JD 2459758.358)     12.87 ± 0.02 mag
2022 June 28.941 (JD 2459759.441)     12.81 ± 0.02 mag
2022 June 29.885 (JD 2459760.385)     12.77 ± 0.04 mag
2022 June 30.841 (JD 2459761.341)     12.70 ± 0.04 mag
2022 July 01.861 (JD 2459762.361)      12.61 ± 0.02 mag
2022 July 03.856 (JD 2459764.356)      12.86 ± 0.05 mag
I - band magnitudes:
2022 July 01.854 (JD 2459762.354)      12.14 ± 0.02 mag
2022 July 03.857 (JD 2459764.357)      12.43 ± 0.04 mag

Our photometric data are obtained with the 50/70-cm Schmidt telescope and the 2-m RCC telescope at Rozhen NAO, Bulgaria. Data were calibrated using stars A, B, C, F from Smith et al (1985, AJ, 90, 1184).

The work was partially supported by the Ministry of Education and Science of the Republic of Bulgaria, National RI Roadmap Project DO1-383/18.12.2020 and NSF Bulgaria grant DN18/10-11.12.2017.