FACT and MAGIC measure an increased gamma-ray flux from the HBL 1ES 1959+650
ATel #9203; A. Biland (ETH Zurich), R. Mirzoyan (Max-Planck-Institute for Physics) on behalf of the FACT and MAGIC Collaborations
on 1 Jul 2016; 18:08 UT
Credential Certification: Daniela Dorner (email@example.com)
Subjects: Gamma Ray, VHE, AGN, Blazar
Referred to by ATel #: 9239
The FACT and MAGIC collaborations report the measurement of an enhanced
gamma-ray flux at about 1 TeV from a position consistent with the HBL
1ES 1959+650 (z=0.047, Schachter et al. 1993, ApJ, 412, 541).
Recent activities from this source were reported in gamma rays (ATel
#9010, #9139, #9148, #9168), IR (ATel #9070) and X-rays (ATel #9121),
and since Summer 2015 several periods of enhanced activity have been
observed. After the bright flare of MJD 57552 (ATel #9148), the flux
decayed within 1-2 nights to a level of 0.5-1 Crab units and stayed
around or below that level for about 15 days.
From MJD 57570.04 till 57570.18, FACT measures an increased average
flux corresponding to at least 2 Crab units. The source is detected
with about 13 standard deviations in 3.3 hours of observation. The
results of a preliminary, automatic quick look analysis are publicly
shows the 20-minute-binned background subtracted light curve. These
values are corrected neither for the effect of large zenith distance
under which the source is observable nor for the amount of
night-sky-background light, with both effects decreasing the measured
gamma rate. The measurement might be affected the meteorologic
phenomenon calima possibly causing an apparent lower flux.
FACT is regularly monitoring 1ES 1959+650. Currently, it is observing
the source each night from 1:00 to 04:30 UTC, if weather conditions
permit. The FACT contact person for this source is D. Dorner
The preliminary analysis of the MAGIC data taken from MJD 57570.00 to
57570.21 indicates a flux of about 2.6 that of the flux from the Crab
Nebula above 300 GeV. MAGIC observations on 1ES 1959+650 will continue
during the next days, and multi-wavelength observations are encouraged.
The MAGIC contact person for these observations is R. Mirzoyan
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.
The First G-APD Cherenkov Telescope (FACT) is an Imaging Atmospheric
Cherenkov Telescope with 9.5 sqm mirror area, located next to the two
MAGIC telescopes. It is pioneering the usage of silicon photosensors
and monitoring bright, variable sources at energies above 750 GeV. The
Collaboration includes ETH Zurich and the Universities of Dortmund,
Geneva and Wuerzburg.