New activity period of FSRQ Ton 599 in progress
ATel #16663; V. V. Vlasyuk, O. I. Spiridonova (Special Astrophysical Observatory of the Rus. Ac. Sci.)
on 19 Jun 2024; 10:29 UT
Credential Certification: Alexander Moskvitin (mosk@sao.ru)
Subjects: Optical, Quasar
Referred to by ATel #: 16709
The flat spectrum radio quasar (FSRQ) Ton 599 (4C 29.45, PKS 1156+295) probably begin new activity period through last two weeks.
After completing of two-peak behavior in last March (ATel #16557) its brightness in April-May varied between 15m.5 and 16m.2 (R-band) with only one exception --- fast flare up to R=14m.85 was detected at May, 1st using by our 1-m and 0.5-m reflectors.
But from the beginning of June (MJD 60465.8) its brightness have started stable exponential growth from R=15m.9 and achieved value of R=15m.07 during last night (MJD 60479.8). The light curve between these epochs can be well approximated by linear law with a slope about 0m.05 per day. This value is close to slope of Ton 599 light curve (about 0m.04 per day) at epoch, which preceded its outburst (R=13m.7) in last February.
Typical accuracy of our data was about 0m.015 under good transparency and seeing value (FWHM) about 1.5 arcsec. The estimates of brightness from the both --- 1-m and 0.5-m --- telescopes agree well within range 0m.01--0m.02.
Data from our both telescope were calibrated using by stars 1--4 from (Raiteri C.M. et al., A&AS 130, 495, 1998).
More accurate reduction is necessary. We strongly encourage further multi-wavelength observations.
