IceCube-221124A

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

On 22-11-24 at 15:46:02.26 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 2.79 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/137296_24212476.amon), more 
sophisticated reconstruction algorithms have been applied offline, with 
the direction refined to:

Date: 22-11-24
Time: 15:46:02.26
RA: 298.92 (+2.65/-2.92 deg  90% PSF containment) J2000
Dec: +3.73 (+1.04/-1.23 deg 90% PSF containment) J2000

We encourage follow-up by ground and space-based instruments to help 
identify a possible astrophysical source for the candidate neutrino.

One gamma-ray source listed in the 4FGL Fermi-LAT catalog is located in 
the 90% uncertainty contour. The source is 4FGL J1956.1+0234 located at 
RA=299.04 deg, Dec=2.57 deg (J2000 coordinates), 1.16 deg away from the 
best fit position.

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

J. Sinapius (DESY-Zeuthen), S. Garrappa (Ruhr-Universitaet Bochum) and 
S. Buson (Univ. of Wuerzburg) on behalf of the Fermi-LAT collaboration:

We report an analysis of observations of the vicinity of the IC221124A 
high-energy neutrino event (GCN 32980
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 ) with all-sky survey data from the 
Large Area Telescope (LAT), on board the Fermi Gamma-ray Space 
Telescope. The IceCube event was detected on 2022-11-24 at 15:46:02 UT 
(T0) with J2000 position RA = 298.92 (+2.65, -2.92) deg, Decl. = +3.73 
(+1.04, -1.23) deg (90% PSF containment). One cataloged gamma-ray (>100 
MeV) source is located within the 90% IC221124A localization region 
(4FGL-DR3; The Fermi-LAT collaboration 2022, ApJS, 260, 53). This is 
4FGL J1956.1+0234, associated with the blazar of uncertain type 2MASS 
J19562808+0234250. Based on a preliminary analysis of the LAT data over 
the timescales of 1-day and 1-month prior to T0, this object is not 
significantly detected (> 5 sigma).

We searched for intermediate (days to years) timescale emission from a 
new gamma-ray transient source. Preliminary analysis indicates no 
significant (> 5 sigma) new excess emission (> 100 MeV) at the IC221124A 
best-fit position. Assuming a power-law spectrum (photon index = 2.0 
fixed) for a point source at the IC221124A best-fit position, the >100 
MeV flux upper limit (95% confidence) is < 7.5e-10 ph cm^-2 s^-1 for 
~14-years (2008-08-04 to 2022-11-24 UTC), and < 9.9e-9 (<4.7e-8) ph 
cm^-2 s^-1 for a 1-month (1-day) integration time before T0.

Since Fermi normally operates in an all-sky scanning mode, regular 
monitoring of this region will continue. For these observations the 
Fermi-LAT contact persons are S. Garrappa (simone.garrappa at 
ruhr-uni-bochum.de), J. Sinapius (jonas.sinapius at desy.de) and S. 
Buson (sara.buson at uni-wuerzburg.de).

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.

D. R. Xiong, J. M. Bai, Y. F. Fan, K. Ye, C. J. Wang, Y. X. Xin, B. L. Lun, J. R. Mao, L. Xu, X. G. Yu, K. X. Lu, X. Ding, D. Q. Wang (Yunnan Observatories), A. J. Castro-Tirado, E. Fernandez-Garcia, Y. D. Hu (IAA-CSIC) and C. J. Perez del Pulgar (UMA) on behalf of the BOOTES team report:<p>

 

On 2022-11-24 at 15:46:02.26 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin (GCN 32980
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 ). The gamma-ray source 4FGL J1956.1+0234 (RA=299.04 deg, Dec=2.57 deg, J2000) is located in the 90% uncertainty contour, and 1.16 deg away from the best fit position (GCN 32980
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 , 32983
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 ). <p>

 

We observed the gamma-ray source 4FGL J1956.1+0234 with BOOTES-4/MET and BOOTES-2/TELMA 0.6m automatic optical telescopes on Nov 25, 26, and 27. We did not detect any new optical source within localizationof the gamma ray source. The upper limits of magnitudes were calculated using six bright stars in the same frame and the APASS9 catalogue as reference. The upper limits of magnitudes (without being corrected for Galactic extinction) are given as follows. <p>

MJD-T0 (day) | UT(Start) | Upper Limits (mag) | Exposure Time | Filter | Telescope <p>

--------------------------------------------------------------------------------------------------------------<p>

0.86 | 2022-11-25T12:25:17.41 | 18.718 (0.04) | 11*30s | SDSS-i | BOOTES-4 <p>

0.87 | 2022-11-25T12:40:37.86 | 19.567 (0.07) | 8*30s | Clear | BOOTES-4 <p>

1.14 | 2022-11-25T19:04:23.56 | 18.756 (0.07) | 30*30s | SDSS-i | BOOTES-2 <p>

1.84 | 2022-11-26T11:52:03.53 | 19.347 (0.04) | 7*60s | SDSS-i | BOOTES-4 <p>

2.82 | 2022-11-27T11:29:08.99 | 19.80 (0.06) | 24*60s | SDSS-i | BOOTES-4 <p>

--------------------------------------------------------------------------------------------------------------<p>

 

The Burst Optical Observer and Transient Exploring System (BOOTES) is a world-wide automatic telescope network which aims to repaid follow-up of transient and astrophysical sources in the sky for which the first station was installed in 1998 (Hu et al. 2021). The fourth station of the BOOTE Network, BOOTES-4/MET, is located at the Lijiang Observatory of the Yunnan Observatories of China (Xiong et al. 2020). The BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) in Algarrobo Costa (Malaga, Spain). <p>

 

We acknowledge the support of these staffs from the BOOTES telescope networks.

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


IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-221124A (https://gcn.gsfc.nasa.gov/gcn3/32980.gcn3
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 ) in a time range of 1000 seconds centered on the alert event time (2022-11-24 15:37:42.260 UTC to 2022-11-24 15:54:22.260 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-221124A. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-221124A is 1.4e-01 GeV cm^-2 in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 3e+02 GeV and 1e+05 GeV.


A subsequent search was performed including 2 days of data centered on the alert event time (2022-11-23 15:46:02.260 UTC to 2022-11-25 15:46:02.260 UTC). In this case, we report a p-value of 1.00, consistent with no significant excess of track events. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-221124A is 1.6e-01 GeV cm^-2 in a 2 day time window.


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<mailto:roc@icecube.wisc.edu>.


[1] IceCube Collaboration, R. Abbasi  et al., ApJ 910 4 (2021)