Optical brightening of 4C 31.03
ATel #15763; Masaki Tsuboi (Association of Hiroshima Astronomers), Koji S. Kawabata, Ryo Imazawa, Yasushi Fukazawa, Hiromitsu Takahashi, Tsunefumi Mizuno, Tatsuya Nakaoka, Makoto Uemura (Hiroshima University), Mahito Sasada (Tokyo Institute of Technology)
on 17 Nov 2022; 15:37 UT
Credential Certification: Koji Kawabata (kawabtkj@hiroshima-u.ac.jp)
Subjects: Optical, Gamma Ray, AGN, Blazar
We report on the recent optical brightening of the blazar 4C 31.03 (= 4FGL J0112.8+3208), identified by the long-term monitoring observations with the 35-cm telescope at Tsuboi Observatory in Hiroshima City. It showed a temporal increase of the optical brightness up to 16.1 mag (unfiltered CCD ST-10XE) around JD=2459821 and soon decayed. After JD=2459843 the optical brightness again increased and reached 15.0 mag on JD=2459890, ~3 mag brighter than the quiescent level. We observed 4C 31.03 with the 1.5-m Kanata Telescope at Higashi-Hiroshima Observatory and the Hiroshima Optical and Near-InfraRed camera (HONIR) on JD=2459899 in imaging and polarimetry mode. Our preliminary analysis shows the optical and near-infrared magnitudes of V=15.3 mag, R=14.9 mag, J=14.2 mag, Ks=13.5 mag and the polarization of p=6.7% in J-band. We also confirmed that the gamma-ray photon flux from this object shows a temporal increase within recent ~100 days in Fermi LAT Light Curve Repository. Further multi-wavelength observation is encouraged.
