Fermi LAT observations of the PKS 1510-089 outburst.

ATel #1743; Andrea Tramacere (CIFS Torino/SLAC Stanford) on behalf of the Fermi Large Area Telescope Collaboration
on 26 Sep 2008; 01:09 UT
Credential Certification: Gino Tosti (tosti@pg.infn.it)

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The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope (formerly GLAST) (launched June 11, 2008), has observed an increase of the gamma-ray activity starting on 13 September 2008, from a source positionally consistent with PKS 1510-089 (Position J2000.0: RA=15h12m50.5329s, DEC=-09d05m59.828s, Johnston, K. J et al., 1995, AJ, 110,880J). A source consistent with this object was also detected by the AGILE satellite on 03 March 2008 (F., D'Ammando et. al, ATEL #1436).

Preliminary analysis indicates that the source has brightened to a gamma-ray flux (E>100MeV) greater than the pre-defined LAT flaring source reporting threshold of 2x10-6 photons cm-2 s-1. This object is a well known Flat Spectrum Radio Quasar (z= 0.360 +/- 0.002, D. J. THOMPSON et al., 1990, PASP,102,1235T) with a pronounced UV excess, presenting strong analogies to 3C273 (Villata M. et al.1997,A&AS,121,119V). It was detected by EGRET as 3EG J1512-0849 but at a much lower flux (EGRET flux: 5+/-2 x10-7 photons cm-2 s-1, R.C.Hartman et al., 1999, ApJS,123,79H).

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. PKS 1510-089 is one of the "LAT Monitored Sources" (http://fermi.gsfc.nasa.gov/ssc/data/policy/LAT_Monitored_Sources.html), and consequently, a preliminary, uncalibrated estimation of the gamma-ray flux observed by Fermi LAT is publicly available at (http://fermi.gsfc.nasa.gov/ssc/data/access/). In consideration of the ongoing activity of this source we strongly encourage multiwavelength observations. For this source the Fermi LAT contact person is Andrea Tramacere (tramacer@slac.stanford.edu).

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.