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VERITAS Discovery of Very High-Energy Gamma-Ray Emission from 1FGL J0648.8+1516

ATEL # 2486; Rene A Ong (UCLA) for the VERITAS Collaboration; David Paneque (SLAC/KIPAC) on behalf of the Fermi Large Area Telescope (LAT) Collaboration
on 17 Mar 2010; 17:27 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Rene Ong (

Subjects: Gamma Ray, >GeV, Request for Observations, AGN

The VERITAS Collaboration reports the discovery of very high energy (VHE; E>100 GeV) gamma-ray emission from the source VER J0648+152. This source is consistent with the Fermi-LAT gamma-ray source 1FGL J0648.8+1516 (RA 06 48 49.7, dec +15 16 22, J2000) and the radio and X-ray source RGB J0648+152 (RA 06 48 47.6, dec +15 16 25, J2000), of unknown redshift. The new source was identified as a promising candidate for VHE emission based upon an analysis of >10 GeV photons detected by Fermi-LAT. The Fermi-LAT source is reported in the 1FGL catalog as having a photon index of 1.81+-0.11 and a flux in the 1-100 GeV band of (1.76+-0.33)E-9 cm^-2 s^-1. VHE gamma rays were subsequently detected in ~6 hours of good-quality observations made between 4 March 2010 and 16 March 2010 with the VERITAS atmospheric-Cherenkov telescope array. Analysis of the VERITAS data yields a detection of ~90 gamma rays from a source position that is consistent with 1FGL J0648.8+1516, corresponding to a statistical significance of 5 standard deviations. The observed VHE flux is ~2% of the Crab Nebula flux above 200 GeV.

A request for ToO observations with Swift has been approved. Observations at other wavelengths and efforts to determine the redshift of this object are encouraged. Questions regarding the VERITAS observations should be directed to Rene Ong ( The LAT contact person for this object is David Paneque (


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