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Fermi LAT detection of renewed gamma-ray flaring activity from the radio galaxy NGC 1275 (Perseus A)

ATel #4753; Stefano Ciprini (ASI ASDC & INAF OAR, Rome), on behalf of the Fermi Large Area Telescope Collaboration
on 21 Jan 2013; 22:44 UT
Credential Certification: Stefano Ciprini (stefano.ciprini@asdc.asi.it)

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

Referred to by ATel #: 7239, 8219

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed GeV gamma-ray flaring activity from a source positionally consistent with NGC 1275 (also known as 2FGL J0319.8+4130, Nolan et al. 2012, ApJS, 199, 31, as Perseus A and 3C 84) a radio galaxy located at the center of the Perseus galaxy cluster (see also Abdo et al. 2009, ApJ, 699, 31). The source has radio coordinates R.A.: 49.95067 deg, Dec: 41.51170 deg, (J2000, Beasley et al. 2002, ApJS, 141, 13) and redshift z=0.017559+/-0.000037 (Strauss et al. 1992, ApJS, 83, 29).

Preliminary analysis indicates that on 2013 January 20, NGC 1275 was in a high state with an average daily gamma-ray flux (E>100MeV) of (1.1+/-0.3) x 10^-6 photons cm^-2 s^-1 (error statistical only), about 6 times greater than the average flux reported in the second Fermi LAT catalog (2FGL). Fermi already observed increased GeV activity from this blazar in 2010 July (ATel#2737), with very high energy gamma-ray emission discovered by the MAGIC imaging air Cherenkov telescopes (ATel#2916). This renewed activity is characterized by a GeV flux significantly larger than the flare of 2010 July and the 2009 April-May flux level (Kataoka et al. 2010, ApJ, 715, 554). NGC 1275 has been in a relatively high gamma-ray state in the last months and now the GeV flux is reaching the highest historical value observed for the source.

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 encourage multiwavelength observations. The Fermi LAT contact persons for this source are J. Kataoka (kataoka.jun@waseda.jp) and C.C. Cheung (Teddy.Cheung@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.