Fermi LAT detection of a GeV flare from BL Lac PKS 0537-441
ATel #2124; D. Bastieri (INFN/University Padova) on behalf of the Fermi Large Area Telescope Collaboration
on 10 Jul 2009; 20:32 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Dario Gasparrini (dario.gasparrini@asdc.asi.it)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Quasar
Referred to by ATel #: 2591
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 0537-441, one of
the most variable BL Lac objects (z=0.894, Peterson et al. 1976, ApJ,
207, L5).
LAT observations have shown an increasing flux for the past three
weeks, reaching, above 100 MeV, 1.0 +/- 0.4 10^-6 ph cm^-2 s^-1 on
July 8. A similar activity was previously reported by LAT in October
2008 (ATel #1759).
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 these sources we strongly encourage
multiwavelength observations. The Fermi LAT contact persons for this
source is Gino Tosti (tosti@pg.infn.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.
