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ATEL # 2737; D. Donato (NASA/GSFC), D. Wood (NRL), C. C. Cheung (NRC/NRL) on behalf of the Fermi Large Area Telescope Collaboration
on 14 Jul 2010; 21:19 UT
Password Certification: Davide Donato (firstname.lastname@example.org)
Subjects: Gamma Ray, AGN
Referred to by ATEL #: 2916
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 NGC 1275 (1FGL J0319.7+4130, Abdo et al. 2010, ApJS, 188, 405), a radio galaxy located at the center of the Perseus cluster (see also Abdo et al. 2009, ApJ, 699, 31).
Preliminary analysis indicates that the source began brightening on June 26, 2010 with a daily average gamma-ray flux (E>100MeV) of (0.7 +/-0.3) x 10^-6 photons cm^-2 s^-1 (errors are statistical only). Additional analysis revealed the same peak flux level was reached on several subsequent days, and as recently as July 14. The peak flux is a factor of ~3 greater than its average observed during the first year of Fermi observations (Abdo et al. 2010), and is larger than the flare detected previously in April-May 2009 (Kataoka et al. 2010, ApJ, 715, 554).
Since Fermi operates in an all-sky scanning mode, regular monitoring of this source will continue. In consideration of the ongoing activity of this source we strongly encourage multiwavelength observations. The Fermi LAT contact persons for this source are J. Kataoka (kataoka.jun at waseda.jp) and C.C. Cheung (Teddy.Cheung.ctr at nrl.navy.mil).
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.