Fermi LAT Detection of Brightening of the Galactic Plane Source 3EG J0903-3531
ATel #1771; E. Hays, C. C. Cheung (NASA/GSFC), L. Reyes (U. Chicago), on behalf of the Fermi Large Area Telescope Collaboration
on 8 Oct 2008; 21:17 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Teddy Cheung (ccheung@milkyway.gsfc.nasa.gov)
Subjects: Gamma Ray, >GeV, Transient
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 in flux from a gamma-ray source in the Galactic Plane consistent with the location of 3EG J0903-3531 (R. Hartman et al. 1999, ApJS, 123, 79) starting on 6 October 2008. The preliminary LAT position is J2000.0: RA=136.25 deg, DEC=-35.45 deg (l=259.59 deg, b=+7.73 deg) with an error circle radius 0.08 deg (statistical). The systematic error on the location is smaller than the statistical error.
Preliminary analysis indicates that the source has brightened, with a
gamma-ray flux (E>100MeV) exceeding previous levels
detected by EGRET (average EGRET flux: 1.6x10-7 photons cm-2 s-1; peak flux 3.2x10-7 photons cm-2 s-1).
The source activity did not reach the public reporting threshold of 2x10-6 photons cm-2 s-1 that would trigger a public data release.
Because Fermi operates in an all-sky scanning mode, regular gamma-ray
monitoring of this source will continue. In consideration of the
activity of this source we strongly encourage multiwavelength observations. For this source the Fermi LAT contact person is C.C. Cheung (e-mail: Teddy.Cheung@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.
