Fermi-LAT detection of renewed gamma-ray activity from the radio galaxy NGC 1275

ATel #17937; Pfesi van Zyl (South African Radio Astronomy Observatory, SARAO), and Pietro Monti-Guarnieri (University of Trieste and INFN Trieste), on behalf of the Fermi Large Area Telescope Collaboration
on 2 Aug 2026; 19:39 UT
Credential Certification: Pfesesani van Zyl (pfesi24@gmail.com)

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The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed renewed gamma-ray activity from a source positionally consistent with the radio galaxy NGC 1275, also known as Perseus A, 3C 84 and 4FGL J0319.8+4130 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with 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 this source was in an elevated gamma-ray emission state on August 1, 2026, with a daily averaged gamma-ray flux (E>100MeV) of (1.8+/-0.2) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor of more than 5 relative to the average flux reported in the fourth data release of the fourth Fermi-LAT catalog (4FGL-DR4, Ballet et al. 2023, arXiv:2307.12546). The corresponding photon index is 2.0+/-0.1 and is consistent with the 4FGL-DR4 value of 2.12+/-0.01 within the uncertainties. We have also detected two high-energy photons at 13 and 75 GeV associated with the source at a confidence level p > 0.999 on the same day. A VHE photon with energy E=300 GeV was also associated with the source on July 31, 2026 at 23:11:23.6 UT, with a probability of p > 0.998. The Fermi-LAT Collaboration has previously reported flaring activity from this source in ATels #16988, #8219, #8219, #4753, and #2737.

Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. A preliminary estimation of the daily gamma-ray flux observed by Fermi-LAT is publicly available via the LAT Daily Monitored Source List ( https://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/source/NGC_1275 ). A preliminary light curve for NGC 1275 can be accessed via the Fermi-LAT Light-Curve Repository at this link. We encourage multifrequency observations of this source. The Fermi-LAT contact persons for this source are J. Kataoka (kataoka.jun at waseda.jp) and C.C. Cheung (chi.c.cheung2.civ at us.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.