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Fermi LAT detection of a GeV flare from High-redshift Blazar PKS 0537-286

ATel #10356; C. C. Cheung (Naval Research Laboratory), on behalf of the Fermi Large Area Telescope Collaboration
on 8 May 2017; 13:20 UT
Credential Certification: Teddy Cheung (ccheung@milkyway.gsfc.nasa.gov)

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

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 flat spectrum radio quasar PKS 0537-286 (RA = 84.9761725 deg, Decl.= -28.6655406 deg, J2000; Johnston et al. 1995 AJ 110, 880), at high-redshift, z=3.104 (Osmer et al. 1994 ApJ 436, 678).

Preliminary analysis indicates that the source on May 5 and 6, 2017 showed a bright gamma-ray outburst with respective daily fluxes (E>100MeV) of (1.4 +/- 0.2) x10^-6 ph cm^-2 s^-1 and (1.1 +/- 0.2) x10^-6 ph cm^-2 s^-1 (errors are statistical only), a factor of about 30x greater than reported in the 3FGL catalog (3FGL J0540.0-2837; Acero et al. 2015 ApJS 218, 23). The single power-law photon indices were 2.4 +/- 0.2 (May 5) and 2.5 +/- 0.2 (May 6), and comparable to the 3FGL average value of 2.78 +/- 0.06.

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue and its light curve will be available at the Fermi Science Support Center page (see http://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/ ). In consideration of the activity of this source we encourage multiwavelength observations. The Fermi LAT contact person for this source is C. C. Cheung (Teddy.Cheung at nrl.navy.mil).

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.