The optical and near-infrared follow-up observations of flaring blazar BL Lacertae using Kanata Telescope
ATel #14356; R. Imazawa, N. Hazama, M. Sasada, Y. Fukazawa (Hiroshima University)
on 29 Jan 2021; 05:10 UT
Credential Certification: Mahito Sasada (sasadam@hiroshima-u.ac.jp)
Subjects: Infra-Red, Optical, AGN, Black Hole, Blazar
BL Lacertae is on an active state in optical (ATel #13930, #13956, #13958 #14065, ), X-ray (ATel #14069), and gamma-ray (ATel #13933, #13963, #13964, #14032, #14072) wavelengths since August 2020, also on the other active state since October 2020 (Atel #14065, #14069, #14072, #14081, #14096). BL Lacertae showed a historical brightness in the optical bands on Jan. 17, 2021 (Atel #14328, #14329). Since August 2020, we have performed optical and near-infrared photometric and polarimetric monitoring to the object using Hiroshima Optical and Near-InfraRed camera (HONIR; Akitaya al. 2014, Proc. SPIE, 9147, 91474O) attached to 1.5-m Kanata telescope at Higashi-Hiroshima Observatory.
The measured magnitudes (Vega system) and polarization degree(PD) in the optical and near-infrared bands are shown below:
MJD V R I J H Ks PD_R(%) PD_J(%)
59229.450 12.61+/-0.06 11.77+/-0.01 10.77+/-0.01 9.85+/-0.03 8.95+/-0.03 8.17+/-0.04 10.57+/-0.09 9.33+/-0.26
59233.450 12.42+/-0.01 11.70+/-0.01 10.75+/-0.01 9.87+/-0.04 9.12+/-0.07 8.27+/-0.03 13.51+/-0.08 13.77+/-0.27
59234.452 12.62+/-0.01 11.86+/-0.02 10.92+/-0.01 9.92+/-0.03 9.04+/-0.03 8.27+/-0.03 5.97+/-0.07 6.92+/-0.18
The optical brightness is calibrated by comparing with magnitudes of nearby field stars in Pan-STARRS DR1 catalog (Chambers et al. 2016, arXiv:1612.05560) and color transformation (Tonry et al. 2012, ApJ, 750, 2). The near-infrared brightness is calibrated by nearby stars with the Two Micron All Sky Survey (2MASS) catalog (Skrutskie et al. 2006, AJ, 131, 2, 1163)
