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Fermi LAT detection of a new Gamma-ray Source in the vicinity of PKS B2258-022

ATel #7445; M. Orienti (INAF-IRA Bologna), F. D'Ammando (Univ. Bologna, INAF-IRA Bologna) on behalf of the Fermi Large Area Telescope Collaboration
on 25 Apr 2015; 06:50 UT
Credential Certification: Filippo D'Ammando (filippo.dammando@fisica.unipg.it)

Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Black Hole, Blazar, Quasar

Referred to by ATel #: 7479, 7480

The Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope, has observed strong gamma-ray emission from a new gamma-ray source. The preliminary best-fit location of this gamma-ray source (RA=345.43 deg, Dec=-1.99 deg, J2000) has a 95% containment radius of 0.20 deg (errors are statistical only) for observations on 2015 April 22 and 23. This source is not in any published LAT catalog and was not detected by AGILE or EGRET. The closest candidate counterpart is the flat spectrum radio quasar PKS B2258-022 at redshift z=0.778 (Jackson et al. 2002, A&A, 386, 97) with coordinates RA=345.283 deg, Dec=-1.968 deg (J2000; Beasley et al. 2002, ApJS, 141, 13), at an angular distance of 0.15 deg.

Preliminary analysis indicates that the source brightened in gamma rays on 2015 April 22 and 23 with a daily averaged flux (E > 100 MeV) of (1.2+/-0.3) x10^-6 ph cm^-2 s^-1 and of (0.9+/-0.3) x10^-6 ph cm^-2 s^-1 (errors are statistical only), respectively. The source had a photon index of (2.1+/-0.1).

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. In consideration of the activity of this source we encourage multiwavelength observations. For this source the Fermi LAT contact person is M. Orienti (orienti@ira.inaf.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.