TITLE: GCN CIRCULAR NUMBER: 43768 SUBJECT: IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 26/02/17 11:46:06 GMT FROM: A. Zegarelli at Ruhr University Bochum <azegarelli@icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 26-02-17 at 05:55:24.52 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_BRONZE alert stream. The average astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 2.768 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection. After the initial automated alert, more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 26-02-17 Time: 05:55:24.52 UT RA: 75.89 (+0.52/-0.56 deg 90% PSF containment) J2000 Dec: 14.63 (+0.45/-0.43 deg 90% PSF containment) J2000 No known gamma-ray sources listed in the Fermi 4FGL-DR4 or 3FHL catalogs are located within the 90% uncertainty region of this event. As announced in GCN Circular 43419, IceCube alert notices for high-energy track alerts are now also streamed via Kafka. IceCube Gold/Bronze track alerts are available on the Kafka topic 'gcn.notices.icecube.gold_bronze_track_alerts'. The probability distribution of the true neutrino direction, allowing the extraction of precise 90% containment regions around the best-fit direction, is now available for revised reconstruction of high-energy track alerts. Additional information is available at https://gcn.nasa.gov/missions/icecube. The initial automated alert was not distributed through the classical GCN notice system, and the cause is currently under investigation. Meanwhile, the Kafka notification was streamed with an approximate delay of 30 minutes due to a temporary technical issue. As a result, the initial GCN schema (“record_number” = 0) streamed via Kafka contains some errors (this is not the case for the GCN schema (“record_number” = 1), corresponding to the updated reconstruction, which is sent along with this circular). Specifically: The fields “ra_dec_error” and “far” were sent as strings instead of numerical values. record_number was sent as 1, but it should have been 0. The field “p_astro” was sent as a percentage (30.722) instead of a decimal fraction; the correct value is 0.31. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu View this GCN Circular online at https://gcn.nasa.gov/circulars/43768. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...