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Fermi-LAT Detection of Gamma-ray Emission from PMN J1747-5236

ATel #10721; Roopesh Ojha (NASA/GSFC/UMBC), Bryce Carpenter (CUA/NASA/GSFC) and Janeth Valverde (LLR/Ecole Polytechnique) on behalf of the Fermi Large Area Telescope Collaboration
on 8 Sep 2017; 14:39 UT
Credential Certification: Roopesh Ojha (Roopesh.Ojha@gmail.com)

Subjects: Gamma Ray, >GeV, AGN, Blazar, Quasar

Referred to by ATel #: 10748

The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope has observed a gamma-ray flare from a source positionally consistent with the radio source PMN J1747-5236 with coordinates RA: 17h47m05.68s, Dec: -52d36m32.5s, J2000, (Healey et al. 2007, ApJS, 171, 61). This source is not in any published LAT catalog and was not detected by AGILE or EGRET. Its redshift is unknown.

Preliminary analysis indicates that on 5 September 2017 and 6 September 2017, this source was in a high-flux state, with a daily averaged gamma-ray flux (E>100MeV) of (0.6+/-0.1) X 10^-6 photons cm^-2 s^-1 and (0.7+/-0.2) X 10^-6 photons cm^-2 s^-1, respectively (statistical uncertainty only). The corresponding photon spectral index of 2.1+/-0.2 and 2.2+/-0.2, respectively, is in the typical range for a Fermi blazar.

We note the long-term increase in optical brightness of PMN J1747-5236 reported by Gaia with a recent (13 August 2017) peak: http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia17cbz/

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. We encourage further multifrequency observations of this source. For this source the Fermi LAT contact person is Roopesh Ojha (Roopesh.Ojha@gmail.com).

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.