VERITAS detection of the radio galaxy NGC 1275 with elevated very-high-energy gamma-ray emission

ATel #9690; Reshmi Mukherjee (Barnard College) for the VERITAS Collaboration
on 30 Oct 2016; 22:15 UT
Credential Certification: Reshmi Mukherjee (muk@astro.columbia.edu)

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On October 29, 2016 UTC (MJD 57690), the radio galaxy NGC 1275 (z = 0.01756) was detected with elevated very-high-energy gamma-ray emission during routine snapshot monitoring with the VERITAS array of atmospheric Cherenkov telescopes. Further observations by VERITAS were taken on October 30, 2016 UTC (MJD 57691) resulting in a total of ~5 hours (~5:00 UTC to ~10:00 UTC) of data. A preliminary analysis of these data yields a significant detection with the peak flux (from a run-by-run light curve) being (2.7 +/- 0.67) x 10^-11 cm^-2 s^-1 above 250 GeV (corresponding to 15% of the flux from the Crab Nebula). This is the brightest VHE detection of this source recorded; previous detections are at ~3% of the Crab Nebula from MAGIC (Aleksic et al. 2014, A&A 564, A5) and ~1% Crab Nebula flux from VERITAS (Benbow et al. 2015 https://arxiv.org/abs/1508.07251). We note that an increased activity from NGC 1275 at very-high-energy gamma rays was also reported by MAGIC for the same dates (ATel #9689). VERITAS will continue to observe NGC 1275 and multi-wavelength observations are encouraged. Questions regarding the VERITAS observations should be directed to Reshmi Mukherjee (muk@astro.columbia.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 (http://veritas.sao.arizona.edu).