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Fermi LAT detection of a new gamma-ray transient: J1512-3221

ATEL # 2528; Eric Wallace (University of Washington, Seattle), on behalf of the Fermi LAT Collaboration
on 31 Mar 2010; 22:20 UT
Distributed as an Instant Email Notice (Transients)
Password Certification: Teddy Cheung (

Subjects: Gamma Ray, >GeV, Transients

The Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope, has observed a flare from a new gamma-ray source at RA = 228.04 deg, Dec = -32.36 deg, J2000 (95% error radius 0.30 deg, statistical only). Preliminary analysis indicates that on March 29, 2010, the source was in a high state, with a gamma-ray flux (E>100 MeV) of (1.3 +/- 0.4)*10^-6 photons/cm^2/s, reaching (2.9 +/- 1.0)*10^-6 photons/cm^2/s over the 6 hour period from 6:00-12:00 UTC (statistical uncertainties only). The source was previously detected at (0.2 +/- 0.1)*10^-6 photons/cm^-2/s during the week of March 15-22. Just outside the 95% error circle is the flat-spectrum radio quasar PKS 1510-319 (RA=15h13m21.780s, Dec=-32d09m32.50s, z=1.71; S. Healey, et al. 2008 ApJS, 175, 97).

Since Fermi operates in all-sky survey mode, gamma-ray monitoring of this source will continue. We encourage multi-wavelength observations. The Fermi LAT contact person for this source is Eric Wallace (

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.

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