VERITAS Detection of VHE Gamma-Ray Emission from B2 1811+31
ATel #14104; John Quinn (University College Dublin) for the VERITAS Collaboration
on 20 Oct 2020; 22:31 UT
Credential Certification: John Quinn (john.quinn@ucd.ie)
The VERITAS Collaboration reports the detection of very-high-energy
(VHE; E>100 GeV) gamma-ray emission from the blazar B2 1811+31
(R.A.:18 13 35.2027 Dec.:+31 44 17.620, J2000.0). The VERITAS
observations started after the detection of VHE emission
reported by the MAGIC Collaboration
(ATel #14090),
and spanned the period Oct 15 to Oct 19 2020 (MJD 59137-59141). VERITAS collected 5 h
of exposure resulting in the detection of a gamma-ray signal with a statistical
significance level of 7 standard deviations. The integral flux above
200 GeV was measured to be (1.0 ± 0.2) × 10-11 cm-2 s-1
(∼5% of the Crab Nebula flux), compatible with the flux reported by the MAGIC
collaboration from Oct 4 to Oct 10 2020.
B2 1811+31 is a BL Lac-type blazar at a redshift of 0.117 (Giommi et al. 1991, ApJ, 378, 77)
and has recently shown high levels of activity in the GeV band
(ATel #14060)
and at optical wavelengths
(ATel #14103).
Questions regarding the VERITAS observations should be directed to
John Quinn (john.quinn@ucd.ie). VERITAS (the 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. For further
information see the VERITAS
web site.
