GCN Circular 25225

The IceCube Collaboration (http://icecube.wisc.edu/) reports: 

On 30 July 2019, at 20:50:41.31 UT, IceCube detected a track-like event with high probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_Gold alert stream. The threshold astrophysical neutrino purity for Gold alerts is 50%. This alert has an estimated false alarm rate of 0.68 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 (https://gcn.gsfc.nasa.gov/notices_amon_g_b/132910_57145925.amon), more 
sophisticated reconstruction algorithms have been applied offline, with the direction refined to: 

Date: 2019/07/30 
Time: 20:50:41.31 UT 
RA: 225.79 ( +1.28 -1.43 deg 90% PSF containment) J2000 
Dec: + 10.47 ( +1.14 -0.89 deg 90% PSF containment) J2000 

The Fermi-LAT catalogue source 4FGL J1504.4+1029, associated with the active galaxy PKS 1502+106, is located within the 50% uncertainty region of the event with an offset of 0.31 degrees from the best-fit neutrino location. PKS 1502+106 is an FSRQ at a redshift of 1.84 also listed in the 3FHL catalog of hard Fermi-LAT gamma-ray sources. 

Given the spatial coincidence with this FSRQ, and the high astrophysical neutrino signalness (approximately 67%), we strongly encourage follow-up observations of the neutrino region of interest and of the FSRQ in particular. 

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