Detection of a bright very-high-energy gamma-ray flare from BL Lac with the MAGIC telescopes
ATel #14032; Oscar Blanch (IFAE-BIST, Barcelona), on behalf of the MAGIC collaboration
on 20 Sep 2020; 18:46 UT
Credential Certification: Oscar Blanch (blanch@ifae.es)
Subjects: Gamma Ray, TeV, VHE, Blazar
The MAGIC telescopes have observed an increase in the very-high-energy (VHE; >100 GeV) gamma-ray flux from BL Lacertae. The preliminary analysis of the MAGIC data taken on 2020/09/19 indicates the peak flux was at least three times the flux from the Crab nebula. The flux was variable during the observations and the VHE flux is the highest ever observed from the source.
BL Lacertae is a blazar located at redshift 0.0686 and it has shown several bright VHE gamma-ray flares in the past (http://tevcat.uchicago.edu/?mode=1&showsrc=118). The MAGIC observations were triggered by the flaring activity detected in the last days at GeV energies, as measured with the LAT instrument on board of Fermi, information that was shared by the Fermi-LAT collaboration with the the MAGIC Collaboration (as well as other ground-based gamma-ray instruments) on 2020/09/19. The flaring activity follows a period of multiwavelength activity, during which it reached the historical maximum in the optical band (see ATel #13930, ATel #13956, ATel #13958) and in the high-energy gamma-rays observed by the Fermi-LAT (ATel #13933, ATel #13964).
In the VHE band it was detected by MAGIC during the night of August 9th with flux ~15% of the Crab Nebula Flux above 100GeV (ATel #13963). The typical VHE flux of this source is below the sensitivity of current instruments.
MAGIC observations on BL Lac will continue during the next days and multiwavelength observations are encouraged. The MAGIC contact persons for these observations are O.Blanch (blanch@ifae.es) and E.Lindfors (elilin@utu.fi)
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.
