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GCN Circular 26035

FACT follow-up of ANTARES-Fermi 191011A
2019-10-19T18:14:10Z (5 years ago)
Daniela Dorner at U of Wuerzburg <>
A. Biland (ETH Zurich) reports on behalf of the FACT Collaboration:

AMON and ANTARES announced on Oct 14th the identification of the
coincidence of a high-energy neutrino with a Fermi-LAT photon on Oct
11th 15:54:32 UTC from a position close to the blazar RBS 0413.

Due to safety constraints and not ideal weather conditions, FACT
started observing RBS 0413 only in the night from Oct 17th to Oct 18th.
During this night, only 10 minutes of data have been taken due to not
ideal weather conditions. During the following night, another 170
minutes of data have been taken.

The automatic quick-look analysis does not show any signal from the
observed position. Preliminary results can be found at

 From the results of the quick-look analysis, an upper limit of 20% of
the flux of the Crab Nebula at TeV energies was determined with a
confidence level of 99%.

Contact person: Daniela Dorner (

The First G-APD Cherenkov Telescope (FACT) is an imaging air Cherenkov
telescope monitoring blazars at TeV energies. It is located in the
Observatorio del Roque de los Muchachos on the Canary Island La Palma.
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