[ Previous | Next | ADS ]

Exceptionally high >100 GeV flux state of 1ES 1011+496

ATel #5887; Razmik Mirzoyan (MPI Munich) on behalf of the MAGIC collaboration and Jamie Holder (University of Delaware) on behalf of the VERITAS collaboration
on 14 Feb 2014; 15:30 UT
Credential Certification: Jamie Holder (jholder@physics.udel.edu)

Subjects: X-ray, Gamma Ray, >GeV, TeV, VHE, AGN

Referred to by ATel #: 5888

The MAGIC and VERITAS telescopes have observed relatively long-duration flaring activity from the blazar 1ES 1011+496 at z = 0.212 (RA=10h 15m 04.1s, Dec=+49d 26m 01s). The brightest very high energy (VHE; >100 GeV) gamma-ray flux previously recorded from this blazar is approximately 7% of the flux (>200 GeV) observed from the Crab Nebula (J. Albert et al. 2007, ApJ 667, L21). Recent VERITAS and MAGIC observations exceed roughly 10 times this flux. VERITAS observations were taken almost every night between February 3, 2014 UTC (MJD 56691) and February 11, 2014 (MJD 56699). The preliminary analysis of all good-weather data yields a strong signal of about 3300 gamma rays in 13 hours of exposure, corresponding to a statistical significance of 43 standard deviations. The observed nightly integral flux above 200 GeV ranges between 25% and 75% of the flux measured by MAGIC from the Crab Nebula. Following a VERITAS alert to ground-based VHE observatories, the MAGIC telescopes observed the source nightly from February 6, 2014 UTC (MJD 56694) through February 11, 2014 (MJD 56699). The preliminary analysis of these data results in integral fluxes above 200 GeV (nightly averaged) ranging between of 45% and 75% of the flux from the Crab Nebula. Follow-up observations were also taken with Swift XRT / UVOT and at optical wavelengths. The 0.3-10 keV X-ray flux of 1ES1011+496 is also at the highest level ever seen by Swift (http://www.swift.psu.edu/monitoring/). The latest MAGIC and VERITAS observations performed on the night of February 11, 2014 show the high VHE flux persists. The MAGIC and VERITAS telescopes are entering the full Moon period, however the observations will be resumed on February 20, 2014 (UTC), if the weather conditions permit. Additional multiwavelength observations are encouraged. MAGIC is a system of two 17m-diameter imaging atmospheric Cherenkov telescopes (IACTs) located at the Canary island of La Palma, Spain. VERITAS is an array of four 12-m diameter IACTs located near Tucson, Arizona, USA. VERITAS and MAGIC are sensitive to astronomical sources of gamma-rays with energies ranging from approximately 50 GeV to greater than 50 TeV. The MAGIC contact persons for this campaign are Razmik Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de) and Daniel Mazin (mazin@mpp.mpg.de), and the VERITAS contact persons are Jamie Holder (jholder@physics.udel.edu) and Wystan Benbow (wbenbow@cfa.harvard.edu).