Fermi-LAT detection of a gamma-ray flaring source in the vicinity of PKS 0507+17
ATel #5001; F. D'Ammando (INAF-IRA Bologna) and M. Orienti (INAF-IRA Bologna) on behalf of the Fermi Large Area Telescope Collaboration
on 23 Apr 2013; 07:03 UT
Credential Certification: Monica Orienti (orienti@ira.inaf.it)
Subjects: Gamma Ray, Request for Observations, AGN, Blazar, Quasar
Referred to by ATel #: 9779
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 0507+17 (also known as 2FGL J0509.9+1802, Nolan et al. 2012, ApJS, 199, 31; R.A.= 05h10m02.3691s, Dec.= +18d00m41.582s, J2000.0, Johnston et al. 1995, AJ, 110, 880), a flat spectrum radio quasar at redshift z = 0.416 (Perlman et al. 1998, AJ, 115, 1253). Another possible counterpart for the gamma-ray source 2FGL J0509.9+1802 could be GB6 J0509+1806 (R.A.= 05h09m42.910s, Dec.= +18d06m30.30s, J2000.0, Healey et al. 2007, ApJS, 171, 61), as it was proposed in the Second LAT AGN Catalog (2LAC; Ackermann et al. 2011, ApJ, 743, 171). A recent brightening of PKS 0507+17 has been observed in near-infrared (ATel #4998), suggesting this flat spectrum radio quasar as the most likely counterpart of the gamma-ray flaring source.
Preliminary analysis indicates that on 2013 April 21 the source was in a flaring state, with a daily gamma-ray flux (E > 100 MeV) of (1.8 +/- 0.3) x 10^-6 ph cm^-2 s^-1 (statistical uncertainty only), which represents an increase of a factor of 70 with respect to the average source flux reported in the second Fermi LAT catalog (Nolan et al. 2012, ApJS, 199, 31).
An automated search for flaring sources in the aperture photometry light curves provided by the Fermi Science Support Center (http://fermi.gsfc.nasa.gov/ssc/data/access/lat/2yr_catalog/ap_lcs.php) also shows that this source is in a state of increased emission (http://fermi.gsfc.nasa.gov/ssc/data/access/lat/2yr_catalog/ap_lcs/lightcurve_2FGLJ0509.9p1802.png). Note the listed caveats associated with this analysis.
Since Fermi operates in an all-sky scanning mode, regular monitoring of this source will continue. In consideration of the ongoing activity of this source we encourage multiwavelength observations. The Fermi LAT contact person for this source is Filippo D'Ammando (dammando@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.
