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Fermi LAT detection of GeV flares from blazars PKS 0458-02 and B2 1144+40

ATel #5951; Elisa Antolini (University of Perugia) and Sara Buson (INFN & University of Padova) on behalf of the Fermi Large Area Telescope Collaboration
on 5 Mar 2014; 14:12 UT
Credential Certification: Sara Buson (buson@pd.infn.it)

Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar, Transient

Referred to by ATel #: 6995, 7952

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux from two sources positionally consistent with the flat spectrum radio quasars PKS 0458-02 (also known as 2FGL J0501.2-0155, Nolan et al. 2012 ApJS, 199, 31) and B2 1144+40 (also known as S4 1144+40 and 2FGL J1146.9+4000). PKS 0458-02 has the radio coordinates RA=05h01m12.8098s, Dec=-1d59m14.255s (J2000, Johnston et al. 1995, AJ, 110, 880) and redshift z = 2.286 (Strittmatter et al. 1974, ApJ, 190, 509). B2 1144+40 has the coordinates RA = 11h46m58.2979s, DEC = 39d58m34.304s (J2000, Linford et al. 2012, ApJ, 744, 177) and redshift z = z= 1.090069 +/- 0.000473 (Hewett et al. 2010, MNRAS, 405, 2302). Preliminary analysis indicates that both sources brightened in gamma rays with daily fluxes (E > 100 MeV) of (0.9+/-0.3) x10^-6 ph cm^-2 s^-1 (errors are statistical only) on 2014 March 3, factors of 29 for PKS 0458-02, and 19 for B2 1144+40, greater than the average flux reported in the second Fermi LAT catalog (2FGL). PKS 0458-02 was already detected by the LAT in active state on 2012 September 17 (see ATel#4396).

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. Multiwavelength observations during the ongoing activity of this source are strongly encouraged. The Fermi LAT contact person for B2 1144+40 is Elisa Antolini (e-mail: elisa.antolini@fisica.unipg.it). The Fermi LAT contact person for PKS 0458-02 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.