Fermi LAT detection of a GeV flare from blazar Ton 599 (4C 29.45)

ATel #2795; S. Ciprini (Perugia Univ. / ASI-INAF, Italy), on behalf of the Fermi Large Area Telescope Collaboration
on 17 Aug 2010; 11:09 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Stefano Ciprini (stefano.ciprini@pg.infn.it)

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The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flaring activity from a source positionally consistent with the flat spectrum radio quasar Ton 599, also known as 4C 29.45, OM 295, S3 1156+29, 1FGL J1159.4+2914 (Abdo et al. 2010, ApJS, 188, 405) with VLBI coordinates, (J2000), R.A.: 11h 59m 31.8339s, Dec.: +29d 14m 43.827s, (Kenneth et al. 1995, AJ, 110, 880). The redshift of this source is 0.72449 (Adelman-McCarthy et al. 2008, SDSS6).

Preliminary analysis indicates that Ton 599 on 2010, August 15 was in a high state with an average daily gamma-ray flux (E>100MeV) of (1.2 +/- 0.3) x 10^-6 photons cm^-2 s^-1 (statistical uncertainty only), representing a factor of about 10 times the integrated and average flux reported in the first year catalog.

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. In consideration of the ongoing activity of this source we encourage multiwavelength observations. For this source the Fermi LAT contact persons are S. Ciprini (stefano.ciprini@pg.infn.it) and D. J. Thompson (David.J.Thompson@nasa.gov) .

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.