Renewed flaring phase of blazar SBS 1150+497 after 8 years of quiescence
ATel #13254; Sara Cutini (INFN Perugia) on behalf of the Fermi-LAT collaboration
on 1 Nov 2019; 13:46 UT
Credential Certification: David J. Thompson (David.J.Thompson@nasa.gov)
Referred to by ATel #: 13285
The Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope, has observed a fast gamma-ray flare from a source positionally consistent with the blazar SBS 1150+497 (RA: 11h53m24.4666s, Dec: +49d31m08.830s, J2000, Johnston et al. 1995, AJ, 110, 880), a blazar located at z=0.334 (Lynds & Wills 1968, ApJ, 153, L23). This flare was also reported as a GCN Notice (https://gcn.gsfc.nasa.gov/other/1572532941_fermi.txt).
Preliminary analysis of Fermi-LAT data indicates that the source has brightened in gamma-rays with a daily flux (E>100MeV) of (1.3+/- 0.2) x 10^-6 ph cm^-2 s^-1 (errors are statistical only) on 2019 October 30. This flux is about 40 times higher than the average flux of the source in the fourth Fermi-LAT source catalog (4FGL; Fermi-LAT Collaboration: 2019arXiv190210045T). The photon index is consistent with the value of 2.4 from 4FGL. This source had been in a quiescent state in gamma-rays for the past 8 years (since ATel #3353 http://www.astronomerstelegram.org/?read=3353 ). During the flaring phase, the spectral index remains constant, within the errors, with respect to the average value reported in the 4FGL. This source is one of the "LAT Monitored Sources" and consequently, a preliminary estimation of the daily gamma-ray flux observed by Fermi-LAT is publicly available (link: https://fermi.gsfc.nasa.gov/FTP/glast/data/lat/catalogs/asp/current/lightcurves/1150+497_86400.png).
Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. In consideration of the ongoing activity of this source, we encourage multiwavelength observations. The Fermi-LAT contact person for this source is E. Hays (elizabeth.a.hays@nasa.gov).
The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.
