IceCube-230708A
GCN Circular 34170
Subject
IceCube-230708A - IceCube observation of a high-energy neutrino candidate track-like event
Date
2023-07-08T12:32:13Z (2 years ago)
From
Massimiliano Lincetto at Ruhr-Universitaet Bochum <lincetto@astro.ruhr-uni-bochum.de>
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
On 23-07-08 at 08:17:05.21 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 0.9371 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/138131_35302784.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:
Date: 23-07-08
Time: 08:17:05.21 UT
RA: 270.70 (+3.72 / -4.72 deg 90% PSF containment) J2000
Dec: -8.46 (+2.54 / -2.41 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 Fermi 4FGL-DR3 or 3FHL catalog sources are located in the 90% uncertainty region. The sources are 4FGL J1755.9+0953, 4FGL J1805.6+0615 (PSR J1805+0615) and 3FGL J1751.5+0939 (OT 081) respectively located at 2.22, 2.32 and 3.03 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
GCN Circular 34178
Subject
IceCube-230708A: Upper limits from a search for additional neutrino events in IceCube
Date
2023-07-09T16:33:12Z (2 years ago)
From
Jessie Thwaites at IceCube/U Wisc-Madison <thwaites@wisc.edu>
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-230708A (https://gcn.nasa.gov/circulars/34170) in a time range of 1000 seconds centered on the alert event time (2023-07-08 08:08:45.210 UTC to 2023-07-08 08:25:25.210 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-230708A.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-230708A ranges from 1.3e-01 to 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 2e+02 GeV and 1e+05 GeV.
A subsequent search was performed including 2 days of data centered on the alert event time (2023-07-07 08:17:05.210 UTC to 2023-07-09 08:17:05.210 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-230708A is 1.5e-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.
[1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021)
GCN Circular 34184
Subject
Fermi-LAT gamma-ray observations of IceCube-230708A
Date
2023-07-09T21:14:28Z (2 years ago)
From
Sara Buson at GSFC/Fermi <sara.buson@gmail.com>
S. Garrappa (Weizmann Institute of Science), S. Buson (Univ. Wuerzburg), J. Sinapius (DESY) and C. Bartolini (INFN Bari) on behalf of the Fermi-LAT collaboration:
We report an analysis of observations of the vicinity of the IC230708A high-energy neutrino event (GCN 34170) 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 2023-07-08 at 08:17:05.21 UT (T0) with J2000 position RA = 270.70 (+3.72, -4.72 ) deg, Decl. = -8.46 (+2.54, -2.41) deg (90% PSF containment). Three cataloged gamma-ray (>100 MeV; The Fermi-LAT collaboration 2022, ApJS, 260, 53) sources are located within the 90% IC230708A localization region. Based on a preliminary analysis of the LAT data over a month and day timescale prior T0, these objects are not significantly detected at gamma rays.
We searched for intermediate (days to years) timescale emission from a new gamma-ray source. Preliminary analysis indicates no significant (> 5 sigma) new excess emission (> 100 MeV) at the IC230708A best-fit position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC230708A best-fit position, the >100 MeV flux upper limit (95% confidence) is < 1.2e-9 ph cm^-2 s^-1 for ~15-years (2008-08-04 to 2023-07-08 UTC), and < 3.5e-8 (< 1.1e-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 weizmann.ac.il <http://eizmann.ac.il/>), J. Sinapius (jonas.sinapius at desy.de <http://desy.de/>) and S. Buson (sara.buson at uni-wuerzburg.de <http://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.
GCN Circular 34203
Subject
IceCube-230708A - Correction to GCN Circular 34170
Date
2023-07-11T21:05:10Z (2 years ago)
From
Massimiliano Lincetto at Ruhr-Universitaet Bochum <lincetto@astro.ruhr-uni-bochum.de>
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
The incoming direction of the high-energy track-like event IceCube-230708A reported in GCN circular 34170 included a typo, the correct position is:
Date: 23-07-08
Time: 08:17:05.21 UT
RA: 270.70 (+3.72 / -4.72 deg 90% PSF containment) J2000
Dec: +8.46 (+2.54 / -2.41 deg 90% PSF containment) J2000
We confirm the three sources previously reported in the 90% uncertainty contour. We apologize for any inconvenience this may have caused.
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
GCN Circular 34208
Subject
IceCube-230708A: Upper limits from Swift/BAT-GUANO
Date
2023-07-13T03:09:49Z (2 years ago)
From
Samuele Ronchini at PSU <sjs8171@psu.edu>
Samuele Ronchini (PSU), Gayathri Raman (PSU), Aaron Tohuvavohu (U Toronto), James DeLaunay (U Alabama), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report:
The neutrino candidate (GCN 34203) was inside the coded BAT field of view.
The IceCube notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).
Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 90 seconds of BAT event-mode data from [-45,+45] seconds around the time of the burst. All the requested event mode data was delivered to the ground.
Using the NITRATES analysis (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), we searched for emission on 8 timescales from 0.128s to 16.384s in the interval [-20,+20] seconds around the merger time. We find no evidence for a signal, and derive the following upper limits.
We quote the 5-sigma flux upper limits in the 15-350 keV band, considering IceCube localization, for four spectral templates (soft, normal, and hard GRB-like templates described in [arXiv:1612.02395], and spectral shape from GRB170817A [arXiv:1710.05446]) and for four time bins.
In units of 10^-8 erg/s/cm^2:
Bin duration (s) | hard normal soft GRB 170817A
----------------------------------------------------
0.256 | 10.4 15.0 13.8 15.9
1.024 | 5.3 7.7 7.1 8.1
4.096 | 2.9 4.2 3.8 4.4
16.384 | 1.8 2.6 2.4 2.8
The upper limits as function of sky position are plotted here:
https://doi.org/10.5281/zenodo.8141103
The corresponding fits file can be found here:
https://doi.org/10.5281/zenodo.8140900
GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.
A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/