Title: MAGIC detects exceptionally high activity from PKS 1510-089 at very high energy gamma-rays

ATel #9105; Razmik Mirzoyan (Max-Planck-Institute for Physics, Munich, Germany) on behalf of the MAGIC Collaboration
on 1 Jun 2016; 14:37 UT
Credential Certification: Razmik Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de)

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The MAGIC telescopes have detected an increase in the Very High Energy gamma-ray flux from PKS 1510-089 (RA=15 12 50.5, dec=-09 06 00, J2000.0). The preliminary analysis of the MAGIC data taken on 2016/05/30 for 2.7 hours, indicates a highly significant signal (significance > 60 sigma). The flux at the beginning of the observations (MJD=57538.94) was larger than the flux from the Crab nebula above 150 GeV, and around 50% of the flux from the Crab nebula above 240 GeV, declining towards the end of our observations. This implies an increase of a factor of at least ~5 with respect to the flux reported during the VHE flare detected by MAGIC in May 2015 (http://www.astronomerstelegram.org/?read=7542). We roughly estimate the spectral slope to -4, and the flux at 90 GeV at the beginning of the observations to 5 times the flux from the Crab nebula. Automatic analysis of the MAGIC observations from 2016/05/31 show no significant signal of this source. Quasi-simultaneously to MAGIC observations, we also performed optical observations with a 35cm Celestron telescope at La Palma. The observations confirm the elevated optical state, the R-band magnitude being ~15.1. The light curve is available in the Tuorla Blazar monitoring webpage: http://users.utu.fi/kani/1m/PKS_1510-089_jy.html PKS 1510-089 is a FSRQ at z=0.36 and it is regularly monitored by MAGIC. MAGIC observations on 2016/05/30 were triggered by the alert by the H.E.S.S. collaboration due to a high flux observed on issued on 2016/05/29, and high-state reported in the high energy gamma-ray band as seen by Fermi-LAT (http://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/source/1510-089). H.E.S.S. observations from the night 2016/05/29 were reported on 2016/05/31: http://www.astronomerstelegram.org/?read=9102. MAGIC observations on PKS1510-089 will continue during the following nights, and multi-wavelength observations are encouraged. The MAGIC contact persons for these observations are R. Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de) and D. Dominis Prester (dijana@phy.uniri.hr). 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.