IceCube-230201A

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

On 2023-02-01 at 06:20:54.42 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 2.07 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/137603_30799022.amon) more 
sophisticated reconstruction algorithms have been applied offline, with 
the direction refined to:

Date: 2023-02-01
Time:  06:20:54.42 UT
RA: 345.41 (+2.50/-3.07 deg 90% PSF containment) J2000
Dec: +12.10 (+1.62/-1.53 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.

Three gamma-ray sources listed in the 4FGL Fermi-LAT catalog are located 
within the 90% containment region. The sources are 4FGL J2256.7+1307, 
4FGL J2308.9+1111 and 4FGL J2252.6+1245, located 1.6, 2.0 and 2.3 deg 
away from the best-fit position, respectively.

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 IC230201A
high-energy neutrino event (GCN 33244
Loading...
 
 ) 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 2023-02-01 at 06:20:54.42 UT (T0) with
J2000 position RA = 345.41 (+2.50, -3.07) deg, Decl. = +12.10 (+1.62,
-1.53) deg (90% PSF containment). Three cataloged gamma-ray (>100 MeV; The
Fermi-LAT collaboration 2022, ApJS, 260, 53) sources are located within the
90% IC230201A  localization region. Based on a preliminary analysis of the
LAT data over the timescales of 1-day and 1-month prior to T0, these
objects are 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 IC230201A best-fit
position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a
point source at the IC230201A best-fit position, the >100 MeV flux upper
limit (95% confidence) is < 2.8e-10 ph cm^-2 s^-1 for ~14-years (2008-08-04
to 2023-02-01 UTC), and < 3.6e-9 (<2.4e-7) 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-230201A (https://gcn.gsfc.nasa.gov/gcn3/33244.gcn3
Loading...
 
 ) in a time range of 1000 seconds centered on the alert event time (2023-02-01 06:12:34.421 UTC to 2023-02-01 06:29:14.421 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-230201A. 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-230201A is 1.3e-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 2e+02 GeV and 1e+05 GeV.

A subsequent search was performed including 2 days of data centered on the alert event time (2023-01-31 06:20:54.421 UTC to 2023-02-02 06:20:54.421 UTC). In this case, we report a p-value of 0.17, 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-230201A ranges from 1.5e-01 to 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)

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 2023-02-01 at 06:20:54.42 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. Three gamma-ray sources (4FGL J2256.7+1307, 4FGL J2308.9+1111 and 4FGL J2252.6+1245) listed in the 4FGL Fermi-LAT catalog are located within the 90% containment region (GCN 33244
Loading...
 
 , 33248
Loading...
 
 ).  

We observed the three gamma-ray sources and the best-fit position of IceCube-230201A with BOOTES-4/MET robotic telescope.The magnitude was calculated using bright stars in the same frame and the Pan-STARRS catalogue as reference. We did not detect any optical source within the best-fit position, and also the optical counterparts of the three gamma-ray sources

The upper limits of magnitudes (without being corrected for Galactic extinction) are given as follows. 

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

--------------------------------------------------------------------------------------------------------------

Best-fit position| 2.274 | 23-02-03 12:55:15.82 | 19.3 (0.07) | 6*300s (co-added) | Clear  

J2256.7+1307 | 1.236 | 23-02-02 12:00:06.45 | 17.67 (0.16) | 2*300s (co-added) | Clear 

J2308.9+1111| 1.273 | 23-02-02 12:53:51.65 | 19.748 (0.04) | 2*300s (co-added) | Clear 

J2252.6+1245 | 1.286 | 23-02-02 13:13:22.89 | 19.06 (0.06) | 2*300s (co-added) | Clear 

-------------------------------------------------------------------------------------------------------------

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 BOOTES Network, BOOTES-4/MET, is located at the Lijiang Observatory of the Yunnan Observatories of China (Xiong et al. 2020). We acknowledge the support of these staffs from the BOOTES telescope networks.