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Fermi LAT detection of a high gamma-ray state from high-redshift blazar 0917+449

ATEL # 1902; W. McConville (NASA GSFC, UMD), A.B. Hill (LAOG) on behalf of the Fermi Large Area Telescope Collaboration
on 19 Jan 2009; 19:56 UT
Password Certification: Elizabeth Hays (

Subjects: Gamma Ray, >GeV, AGN
Referred to by ATEL #: 1903

The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope (formerly GLAST, launched June 11, 2008), has observed a steady increase in the gamma-ray activity from a source positionally consistent with the blazar 0917+449 (Position J2000.0: RA=09h20m58.4584s, DEC=+44d41m53.985s, Johnston, K.J. et al., 1995, AJ, 110, 880).

Preliminary analysis indicates that the source is in a high state with a gamma-ray flux (E>100MeV) on January 15, 2009, of (0.9+/-0.2) x10-6 photons cm-2 s-1, which represents an increase of a factor roughly 10 greater than that of previous months. This object, with redshift z=2.19 (Schneider, D.P. et al., 2007, AJ, 134, 102), was detected previously by EGRET as 3EG 0917+4427, with an average flux of (1.4+/-0.2) x10-7 photons cm-2 s-1 (Hartman, R.C. et al., 1999, ApJS, 123, 79).

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 strongly encourage multiwavelength observations. For this source the Fermi LAT contact person is William McConville (

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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