IceCube-220425A
GCN Circular 31944
Subject
IceCube-220425A - IceCube observation of a high-energy neutrino candidate track-like event
Date
2022-04-25T04:08:40Z (3 years ago)
From
Marcos Santander at U. Alabama/IceCube <jmsantander@ua.edu>
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
On 2022-04-25 at 02:44:57.82 UT IceCube detected a track-like event which was selected by the ICECUBE_Astrotrack_GOLD alert stream. We note that, while the average astrophysical neutrino purity for Gold alerts is 50%, this event has a lower probability (~17%). This alert has an estimated false alarm rate of 0.576 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/136568_17854328.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:
Date: 2022-04-25
Time: 02:44:57.82 UT
RA: 268.24 (+1.98, -1.66 deg 90% PSF containment) J2000
Dec: -10.73 (+1.71, -1.48 deg 90% PSF containment) J2000
One gamma-ray source listed in the 4FGL-DR3 Fermi-LAT catalog is located within the 90% containment region for the neutrino event. The source is 4FGL J1752.6-1010 (RA: 268.16 deg, Dec: -10.18 deg J2000), 0.56 deg away from the best-fit neutrino candidate 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 31948
Subject
IceCube-220425A: MASTER: flaring blazar TXS 1742-078 as the possible neutrino source candidate
Date
2022-04-25T15:44:17Z (3 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
K.Zhirkov, V.Lipunov, E.Gorbovskoy, G.Antipov, D.Vlasenko, A.Kuznetsov,
N.Tyurina, P.Balanutsa, A.Chasovnikov, D.Kuvshinov, V.Topolev,Ya.Kechin,
Yu.Tselik, K.Minkina
(Lomonosov Moscow State University, SAI, Physics Department),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),
N.M.Budnev, O.Gress,
(ISU,API),
C.Francile, R. Podesta, C.Lopez, F. Podesta
(Observatorio Astronomico Felix Aguilar OAFA),
D.A.H.Buckley
(SAAO),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
V.Senik, A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov
(Blagoveschensk Educational State University)
MASTER-OAGH was the first telescope of MASTER-NET to observe IC-220425's
error-box at 2022-04-25 06:35:11 UTC, 13813 sec after the trigger
(Lipunov et al., GCN #31946).
We report on the detection of a flaring blazar TXS 1742-078 (RA=266.3629
Dec=-7.8844).
IC-220425A is a track-like event with an estimated energy of 600 TeV and
signalness of 17%. It was detected at 2022-04-25 02:44:58 UTC
and is centred at RA=268.24 (+1.98, -1.66 deg, 90% PSF containment),
Dec=-10.73 (+1.71, -1.48 deg, 90% PSF containment) J2000(GCN #31944).
The first image of TXS 1742-078 was obtained at 2022:04-25 06:36:32 UTC.
It is located 3.4 deg away from the center of error-box.
Based on our photometry, the blazar is currently experiencing a flaring
episode (W=17.3+/-0.1, no correction for extinction), compared to its
quiscence state (W=19.2+/-0.3). Judging from ATLAS observations(Smith et
al, PASP 132, 2020)(https://fallingstar-data.com/forcedphot/queue/195704/plot.pdf) it is
31944the brightest flare since 2017.
Interestingly enough, after the correction for galactic
extinction(Schlafly and Finkbeiner, 2011) (A_V=3.18), magnitude of TXS
1742-078 (W=14.1+/-0.1) is close to that of TXS 0506+056 during IC-170922A
(W=14.3, no correction for extinction).
Judging from these facts, we highly encourage multiwavelength observations
to determine whether or not this blazar is a source of IC-220425A
The observation and reduction will continue.
The message may be cited.
GCN Circular 31953
Subject
Fermi-LAT Gamma-ray Observations of IceCube-220425A
Date
2022-04-26T17:08:51Z (3 years ago)
From
Sara Buson at GSFC/Fermi <sara.buson@gmail.com>
S. Buson (Univ. of Wuerzburg), S. Garrappa (DESY-Zeuthen) and G. La Mura (LIP) on behalf of the Fermi-LAT collaboration:
We report an analysis of observations of the vicinity of the high-energy IC220425A neutrino event (GCN 31944) 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 2022-04-25 at 02:44:57.82 UT (T0) with J2000 position RA = 268.24 (+1.98, -1.66) deg, Decl. = -10.73 (+1.71, -1.48) deg (90% PSF containment). One cataloged gamma-ray (>100 MeV) source is located within the 90% IC220425A localization region (4FGL-DR3; arXiv:2201.11184; The Fermi-LAT collaboration 2020, ApJS, 247, 33). This is the gamma-ray source 4FGL J1752.6-1010. 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).
4FGL J1752.6-1010 is associated with the flat-spectrum radio object TXS 1749-101 (a.k.a. IVS B1749-101). It has been proposed as promising neutrino emitter candidate by Plavin et al. (2020 ApJ, 894, 101), and tentatively associated with a previously observed EHE IceCube event, i.e. IC181023A (GCN 23375, GCN 23378). The latter was detected by the IceCube Observatory on 2018-10-23 16:37:32.65 UTC (T0) with J2000 position RA = 270.18 (-1.70,+2.00) deg, Decl. = -8.57 (-1.30,+1.25) deg 90% PSF containment.
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 IC220425A best-fit position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC220425A best-fit position, the >100 MeV flux upper limit (95% confidence) is < 3.1e-10 ph cm^-2 s^-1 for ~13-years (2008-08-04 to 2022-04-25 UTC), and < 1.3e-8 (< 2.9e-7) ph cm^-2 s^-1 for a 1-month (1-day) integration time before T0.
Outside the neutrino IC220425A 90% PSF containment lies the gamma-ray source 4FGL J1745.4-0753, a.k.a. 3FHL J1745.4-0752 (The Fermi-LAT collaboration 2014, AAS, 223, 256) and TXS 1742-078. TXS 1742-078 is currently undergoing an enhanced optical state (Zhitkov. et al. 2022, GCN 31948). 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).
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 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.
GCN Circular 31971
Subject
IceCube-220425A: Upper limits from a search for additional neutrino events in IceCube
Date
2022-04-29T16:22:38Z (3 years ago)
From
Abhishek Desai at ICECUBE/U of Wisconsin <desai25@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-220425A (https://gcn.gsfc.nasa.gov/gcn3/31944.gcn3)
in a time range of 1000 seconds centered on the alert event time (2022-04-25 02:36:37.820 UTC to 2022-04-25 02:53:17.820 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-220425A. 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-220425A ranges from 1.2e+00 to 2.2e+00 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 5e+02 GeV and 1e+06 GeV.
A subsequent search was performed including 2 days of data centered on the alert event time (2022-04-24 02:44:57.820 UTC to 2022-04-26 02:44:57.820 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-220425A ranges from 1.1e+00 to 2.3e+00 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)