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High linear polarization of the blazar S4 0954+65

ATel #15414; Rumen Bachev (IA-NAO, BAS, Bulgaria)
on 5 Jun 2022; 22:41 UT
Credential Certification: Rumen Bachev (bachevr@astro.bas.bg)

Subjects: Optical, Blazar

Referred to by ATel #: 15419, 15517

The optical brightness of the blazar S4 0954+65 has dramatically dropped by about 2 magnitudes during the last few days, reaching R=14.95 (+/-0.05) on 2022-06-05, UT 19:45. However, its linear polarization seemed to increase during this period, reaching P = 37 (+/-2)%, with EVPA = 77 (+/-3) degrees about the same time. The polarization rate is far from the synchrotron maximum of 75% (e.g. Rybicki & Lightman, 1979, "Radiative processes in astrophysics", Wiley), but is close to the highest reported polarization rates for a blazar (e.g., PKS 1502+106, P=47%, ATel #11047). Therefore, this object can still be interesting even at a relatively low state of brightness, so further observations are encouraged.

These observations have been performed with the 0.6m telescope of Belogradchik, Bulgaria. All results are preliminary. This research was partially supported by the Bulgarian National Science Fund of the Ministry of Education and Science under grants KP-06-H28/3 (2018), KP-06-H38/4 (2019) and KP-06-KITAJ/2 (2020).