IceCube-221229A

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

On 2022-12-29 at 07:25:27.88 UT IceCube detected a track-like event
with a high probability of being of astrophysical origin.
The event was selected by the ICECUBE_Astrotrack_Gold alert stream.
The average astrophysical neutrino purity for Gold alerts is 50%.
This alert has an estimated false alarm rate of 1.014 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/137487_35344578.amon), more
sophisticated reconstruction algorithms have been applied offline, with
the direction refined to:

Date: 2022-12-29
Time: 07:25:27.88 UT
RA: 31.90 (+1.68/-1.55 deg 90% PSF containment) J2000
Dec: +4.18 (+1.39/-0.84 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.

There are no Fermi 4FGL or 3FHL catalog sources in the 90% uncertainty
region of the event. The nearest gamma-ray source in either catalog is
4FGL J0215.9+0521 (TXS 0213+051) at RA: 33.99 deg, Dec: 5.35 deg J2000
(2.39 deg away from the best-fit event 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

D. R. Xiong, J. M. Bai, Y. F. Fan, K. Ye, C. J. Wang, Y. X. Xin, B. L. Lun, J. R. Mao, X. H. Zhao, 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:

On 2022-12-29 at 07:25:27.88 UT IceCube detected a track-like event with a high probability of being of astrophysical origin (GCN 33122
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 ). 

We observed the best-fit position of IceCube-221229A with BOOTES-2/TELMA 0.6m automatic optical telescope. The magnitude was calculated using three bright stars in the same frame and the SDSS DR16 catalogue as reference. We did not detect any optical source within the best-fit position. The upper limit of magnitude (without being corrected for Galactic extinction) is given as follows. 

Tmid-T0 (day) | UT (start) | Upper Limit (error) | Exposure Time | Filter | Comment

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0.61 | 22-12-29T22:05:40.929 | 19.22 (0.11) | 5*300s (co-added) | Clear | Strong moonlight 

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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 BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) in Algarrobo Costa (Malaga, Spain). We acknowledge the support of these staffs from the BOOTES telescope networks.

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

We report an analysis of observations of the vicinity of the IC221229A 
high-energy neutrino event (GCN 33122
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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 2022-12-29 at 07:25:27.88 
UT (T0) with J2000 position RA = 31.90 (+1.68, -1.55) deg, Decl. = +4.18 
(+1.39, -0.84) deg (90% PSF containment). No cataloged gamma-ray sources 
(>100 MeV; The Fermi-LAT collaboration 2022, ApJS, 260, 53) are located 
within the 90% IC221229A localization region.

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 IC221229A 
best-fit position. Assuming a power-law spectrum (photon index = 2.0 
fixed) for a point source at the IC221229A best-fit position, the >100 
MeV flux upper limit (95% confidence) is < 1.3e-10 ph cm^-2 s^-1 for 
~14-years (2008-08-04 to 2022-12-29 UTC), and < 1.2e-8 (<8.8e-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.

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-221229A (https://gcn.gsfc.nasa.gov/gcn3/33122.gcn3
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 ) in a time range of 1000 seconds centered on the alert event time (2022-12-29 07:17:07.884 UTC to 2022-12-29 07:33:47.884 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-221229A. 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-221229A 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 (2022-12-28 07:25:27.884 UTC to 2022-12-30 07:25:27.884 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-221229A 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)