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MAGIC detects activity from PKS 1424+240 at very-high-energy gamma rays

ATel #10157; Razmik Mirzoyan (Max-Planck-Institute for Physics, Munich), on behalf of the MAGIC collaboration
on 9 Mar 2017; 22:24 UT
Credential Certification: Razmik Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de)

Subjects: Gamma Ray, TeV, VHE, Blazar

The MAGIC telescopes have observed an increase in the very-high-energy (VHE; >50 GeV) gamma-ray flux from PKS 1424+240, RA: 14:27:00.4 and DEC: +23:48:00, J2000.0 (Wenger, M. et al., 2000, A&AS, v.143, 9). The preliminary analysis of the MAGIC data taken on 2017/03/09, indicates an integral photon flux of (7.6 +/- 2.3) x 10^-11 [cm^-2/s] above 70 GeV. The estimated flux corresponds to 10+/-3 % of the Crab Nebula integral flux above the same energy threshold (70 GeV), and shows a hint of elevated flux in comparison with the previous detections (Archambault, S. et al., 2014, ApJL, 785,1, L16 and the references therein). PKS 1424+240 is a BL Lac object located at redshift z=0.604 (Paiano et al. 2017, arXiv:1701.04305) and was previously reported as a VHE gamma-ray emitter by VERITAS (Acciari, V.A. et al., 2010, ApJ 708 L100) and MAGIC (Aleksi?, J. et al., 2014, A&A 567, 135). It is the most distant VHE emitter whose source type is confirmed as a BL Lac object. The MAGIC observations were triggered by the hard spectrum in HE gamma-ray band (0.1-300 GeV), estimated from daily analysis of Fermi data, and showing a photon spectral index = -1.47 +/- 0.28 (TS = 25.9) during 2017/03/06 and 2017/03/07. MAGIC will observe PKS 1424+240 tonight and multi-wavelength observations are encouraged. The MAGIC contact persons for these observations are R. Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de), V. Fallah Ramazani (vafara@utu.fi) and Gaia Vanzo (gvanzo@iac.es). MAGIC is a system of two 17m-diameter Imaging Atmospheric Cherenkov Telescopes located at the Canary island of La Palma, Spain, and designed to perform gamma-ray astronomy in the energy range from 50 GeV to greater than 50 TeV.