Bright Optical State of the VHE Blazar B2 1420+32

ATel #15986; W. Benbow (SAO), P. Fortin (SAO), P. Lusen (UCSC) and D. A. Williams (UCSC)
on 11 Apr 2023; 22:25 UT
Credential Certification: David A. Williams (daw@ucsc.edu)

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We report a bright optical state of B2 1420+32, r' = 14.23+/-0.01 (uncorrected for extinction and the host galaxy contribution; statistical uncertainty only). B2 1420+32 was observed with the 48" Ridge Telescope at the Fred Lawrence Whipple Observatory on MJD 60045.51 (UT 2023-04-11 12:14) as part of a regular monitoring program to study blazars with very high-energy (VHE; >100 GeV) gamma-ray emission. It has generally been increasing in brightness over the last ~25 days, from r'=16.93+/-0.01 on MJD 60021.51 and r'=15.54+/-0.01 on MJD 60032.49. The latest measurement is ~3.2 magnitudes brighter than the median value observed since 2021-02-15, when this blazar was first included in the program. Field stars from AAVSO Photometric All-Sky Survey (APASS) are used for the photometric calibration. B2 1420+32 is classified as a flat spectrum radio quasar (Healey et al. 2007, ApJSS, 171, 61) at a redshift of 0.682 (Hewett & Wild 2010, MNRAS, 405, 2302). VHE gamma rays from B2 1420+32 were observed with the MAGIC telescopes in 2020 January (Mirzoyan 2020, ATel #13412), following a report of GeV gamma-ray flaring detected by Fermi-LAT (Ciprini et al. 2020, ATel #13382). Observations in the R band around the time of the MAGIC gamma-ray detection found magnitudes similar to our current observation (Minev et al. 2020, ATel #13421; D’Ammando et al. 2020, ATel #13428). B2 1420+32 has also been observed to flare in the X-ray (Ramazani et al. 2020, ATel #13417), NIR (e.g. Carrasco et al. 2019, ATel #12379; De et al. 2019, ATel #12941) and radio (Kharinov 2020, ATel #13479; Marchili et al. 2020, ATel #13582; Eppel et al. 2021, ATel #14822) bands. This work is supported by the Smithsonian Astrophysical Observatory and the U.S. National Science Foundation (award PHY-2011420). We are grateful to the staff of the Whipple Observatory for their support of the telescope operations.