VERITAS Detection of VHE gamma-ray flaring from B2 1420+32

ATel #17802; Amy Furniss (UC Santa Cruz) for the VERITAS Collaboration
on 15 May 2026; 01:44 UT
Credential Certification: Amy Furniss (afurniss@ucsc.edu)

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The flat spectrum radio quasar (FSRQ) B2 1420+32 (also known as 4FGL J1422.5+3223, OQ 334) at z = 0.682 (Hewett & Wild 2010, MNRAS, 405, 2302) is a known very high-energy (VHE; E > 100 GeV) gamma-ray emitter. This FSRQ was recently found to be flaring brightly in the radio, NIR, optical and MeV-GeV gamma-ray bands (see, e.g., ATels #17795, #17792, #17790, #17782, #17745, #17654), and was correspondingly observed in April and May 2026 with VERITAS. The VERITAS observations (7.0 h quality selected live time) in 2026 yield a preliminary excess of 120 gamma-ray-like events above the estimated background from the position of B2 1420+32, corresponding to a statistical significance of 5.7 standard deviations (sigma). The FSRQ is not seen in April 2026, and a preliminary analysis of the remaining exposure from May 7 (UTC) to May 14 (UTC) yields a detection of 122 gamma rays (6.3 sigma) in 5.7 h live time. This corresponds to a flux above 150 GeV, F(>150 GeV) = (1.4 +- 0.2) x 10^{-11} cm^{-2} s^{-1} , or ~5% of the Crab Nebula flux above the same threshold. VHE emission was previously observed by both MAGIC (Acciari et al. 2021, A&A 647, A163) and VERITAS (Escudero-Pedrosa 2025, TeVPA 2025 Presentation) during a bright flare in January 2020. The VHE flux detected by VERITAS in May 2026 is similar to those reported for the 2020 flare. VERITAS plans to continue observing B2 1420+32 as feasible and additional multi-wavelength observations are encouraged. Questions regarding the VERITAS observations should be directed to Amy Furniss (afurniss@ucsc.edu). VERITAS (Very Energetic Radiation Imaging Telescope Array System) is located at the Fred Lawrence Whipple Observatory in southern Arizona, USA, and is most sensitive to gamma rays between 85 GeV and 30 TeV (https://veritas.sao.arizona.edu/).