Fermi-LAT detection of a GeV flare from the FSRQ PKS 2345-16

ATel #13172; Dario Gasparrini (SSDC/INFN) and Roberto Angioni (SSDC/INFN) on behalf of the Fermi-LAT collaboration
on 8 Oct 2019; 12:27 UT
Credential Certification: Dario Gasparrini (dario.gasparrini@asdc.asi.it)

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The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed an increasing gamma-ray flux from a source positionally consistent with PKS 2345-16 (RA: 357.010869, Dec: -16.520006, J2000; Beasley, A. J. et al. 2002, ApJS 141, 13B), a flat spectrum radio quasar at redshift z=0.576 (Tadhunter C.N. et al. 1993, MNRAS, 263, 999). Preliminary analysis indicates that the source was in a high state on October 5, 2019, with a daily gamma-ray flux (E>100MeV) of (1.5+/-0.4) x 10^-6 photons cm^-2 s^-1 (statistical uncertainty only), which represents an increase of a factor of 27 with respect to the average source flux reported in 4FGL catalog (The Fermi-LAT collaboration, arXiv:1902.10045). The activity is still ongoing in the next days with a daily flux of (1.5+/-0.4) x 10^-6 and (1.2+/-0.2) x 10^-6 photons cm^-2 s^-1, respectively.

Since Fermi normally operates in an all-sky scanning mode, regular monitoring of this source will continue. This source is being added to the "LAT Monitored Sources" and consequently, a preliminary estimation of the daily gamma-ray flux observed by Fermi-LAT will be publicly available at http://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/ . In consideration of the ongoing activity of this source we strongly encourage multiwavelength observations. For this source, the Fermi-LAT contact persons are D. Gasparrini (dario.gasparrini@ssdc.asi.it) and R. Angioni (roberto.angioni@ssdc.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.