Fermi LAT detection of the first GeV gamma-ray flare from the BL Lac object S5 2007+77
ATel #8635; Sara Cutini (ASDC/INFN) on behalf of the Fermi Large Area Telescope Collaboration
on 4 Feb 2016; 17:25 UT
Credential Certification: Stefano Ciprini (stefano.ciprini@asdc.asi.it)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar, Quasar
Referred to by ATel #: 8642
The Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope, has observed for the first time on daily time-scales gamma-ray outburst activity from a source positionally consistent with the BL Lac object S5 2007+77 (a.k.a. 5BZB J2005+7752, 3FGL J2005.2+7752, Acero et al. 2015 ApJS, 218, 23) at R.A. = 20h 05m 30.9985s, Dec = +77d 52m 43.248s (J2000, Ma et al. 1998, AJ, 116, 516) with redshift z=0.342 (Stickel et al. 1989, A&AS, 80, 103).
Preliminary analysis indicates that on 2016 February 3rd, S5 2007+77 was in a high state with daily averaged flux (E>100 MeV) of (0.8+/-0.1)X10^-6 ph cm^-2 s^-1 and photon spectral index of 1.9+/-0.2 (errors are statistical only). This corresponds to a flux increase of about a factor 25 compared with the baseline flux reported in the Third Fermi-LAT Catalog (3FGL) and the corresponding photon index is marginally harder than the average index 2.219+/-0.042 in the 3FGL catalog. A brightening in the near-IR band was observed in January 2013 (ATel#4751) and October 2015 (ATel#8187).
Since Fermi operates in all-sky survey mode, gamma-ray monitoring of this source will continue. In consideration of the activity of this source we strongly encourage multi-wavelength observations. The Fermi LAT contact person for this source is S. Cutini (sara.cutini@asdc.asi.it)
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.
