IceCube-190819A

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

On 2019-08-19 at 17:34:24.24 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 threshold astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 3.9 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/132974_67924813.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2019-08-19
Time:  17:34:24.24 UT
RA: 148.80 (+2.07 -3.24 deg  90% PSF containment) J2000
Dec: 1.38 (+1.00 -0.75 deg 90% PSF containment) J2000

The Fermi-LAT catalogue source 4FGL J0946.2+0104, associated with a BL Lac object at a redshift of z = 0.58, is located within the 90% uncertainty region of the event with an offset of 1.1 degrees from the best-fit neutrino location. This source is also listed as 3FHL J0946.2+0104 in the 3FHL catalog of hard Fermi-LAT gamma-ray sources.

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

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>

Sergey Molkov (IKI Moscow, Russia), Sandro Mereghetti (INAF IASF-Milano,
Italy),
V. Savchenko, C. Ferrigno (ISDC/UniGE, Switzerland)
J. Rodi (IAPS-Roma, Italy)
A. Coleiro (APC, France)

on behalf of the INTEGRAL multi-messenger collaboration:
https://www.astro.unige.ch/cdci/integral-multimessenger-collaboration

Using INTEGRAL/SPI-ACS realtime data (following [1]) we have performed a
search for a prompt gamma-ray counterpart of the   high-energy neutrino
candidate event IceCube-190819A (GCN 25402
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 ).

At the time of the event (2019-08-19 17:34:24 UTC, hereafter T0),
INTEGRAL was operating in nominal mode. The peak of the event
localization probability was at an angle of 64 deg with respect to the
spacecraft pointing axis. This orientation implies strongly suppressed
(16% of optimal) response of ISGRI, strongly suppressed (26% of
optimal) response of IBIS/Veto, and somewhat suppressed (47% of optimal)
response of SPI-ACS.

The background within +/-300 seconds around the event was rather
stable (excess variance 1.3).

We have performed a search for any impulsive events in INTEGRAL SPI- ACS
(as described in [2]) data.

We do not detect any significant counterparts and estimate a 3-sigma
upper limit on the 75-2000 keV fluence of 3.5e-07 erg/cm^2 (within the
50% probability containement region of the source localization) for a
burst lasting less than 1 s with a characteristic short GRB spectrum
(an exponentially cut off power law with alpha=-0.5 and Ep=600 keV)
occurring at any time in the interval within 300 s around T0. For a
typical long GRB spectrum (Band function with alpha=-1, beta=-2.5, and
Ep=300 keV), the derived peak flux upper limit is ~3.6e-07 (1.3e-07)
erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range.

We report for completness and in order of FAP, all excesses identified
in the search region. We find: 5 likely background excesses:

scale | T | S/N | flux ( x 1e-06 erg/cm2/s) | FAP
3.75 | -114 | 3.9 | 2.64 +/- 0.604 +/- 0.819 | 0.11
5 | -95.2 | 3.5 | 1.94 +/- 0.523 +/- 0.602 | 0.148
0.1 | -2.52 | 3.1 | 1.19 +/- 0.374 +/- 0.367 | 0.499
0.15 | -13.8 | 3.6 | 1.12 +/- 0.305 +/- 0.346 | 0.581
0.15 | -18.3 | 3.7 | 1.15 +/- 0.305 +/- 0.357 | 0.626

Note that FAP estimates (especially at timescales above 2s) may be
possibly further affected by enhanced non-stationary local background
noise. This list excludes any excesses for which FAP is close to
unity.

All results quoted are preliminary.

This circular is an official product of the INTEGRAL Multi-Messenger
team.

[1] Savchenko et al. 2017, A&A 603, A46 [2] Savchenko et al. 2012, A&A
541A, 122S

J. Wood, M. Hui, and D. Kocevski (NASA/MSFC) report on behalf of the Fermi-GBM Team:

For the IceCube high-energy neutrino candidate event 190819A (GCN 25402
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 ), at the event time Fermi-GBM was observing the reported neutrino location at:

RA: 148.80 (+2.07 -3.24 deg  90% PSF containment) J2000
Dec: 1.38 (+1.00 -0.75 deg 90% PSF containment) J2000

There was no Fermi-GBM onboard trigger around the event time of the neutrino candidate. An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM also identified no counterpart candidates. The GBM targeted search, the most sensitive, coherent search for GRB-like signals, was run from +/-30 s around the neutrino candidate time. From this search, no significant signal was found related to IceCube-190819A.

We set upper limits on impulsive gamma-ray emission. Using the representative soft, normal, and hard GRB-like templates (arXiv:1612.02395
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 ), we report the following 3 sigma flux upper limits over 10-1000 keV (in units of 10^-7 erg/s/cm^2):

Timescale  soft     norm     hard
--------------------------------------
0.128 s:   4.1      5.9      12.
1.024 s:   1.5      2.1      4.6
8.192 s:   0.5      0.9      1.5

Antonio Galvan (IA-UNAM), Israel Martinez-Castellanos (UMD) report on
behalf of the HAWC collaboration
(http://www.hawc-observatory.org/collaboration/):

On August 19, 2019 at 17:34:24.24, the IceCube collaboration reported
a track-like very-high-energy event that has a high probability of
being an astrophysical neutrino, IceCube-190819A, at RA = 148.80 deg
and Dec = 1.38 deg, J2000 (GCN circular 25402
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 ). In HAWC's sky, the
neutrino was at zenith of 23.00 deg and setting. We have searched for
a steady source as well as a transient source.


* Search for a steady source in archival data from November 2014 to

May 2018. Assuming a spectral index of -2.3 we searched in a 9.29

degree square around IceCube's reported location. The highest

significance, 2.68 sigma, was at RA = 148.36 deg, Dec = 1.60 deg

(J2000). Note that there are at least 46 trials in this search, so the

post-trials significance is 0.96. We set a time-integrated upper limit
95% CL on gamma rays of:

E^2 dN/dE = 3.20643e-13 (E/TeV)^-0.3 TeV cm^-2 s^-1.


* Search for a transient source.

We integrated from 19:00 UTC to 21:22 UTC. Due to maintaince, we did
not collect data during the period 15:42 UTC to 19:00 UTC,during which
the IceCube location would had been otherwise observable by HAWC.

For this observed period,the most significant location,

within the 9.29 degree square,is 2.29 sigma (RA = 148.37 deg, Dec =
1.70 deg, J2000)  with a post-trials significance of 0.027.

We set a time-integrated upper limit 95% CL on gamma rays of:

E^2 dN/dE = 2.3535e-11 (E/TeV)^-0.3 TeV cm^-2 s^-1.

HAWC is a very-high-energy gamma-ray observatory operating in Central

Mexico at latitude 19 deg. north. Operating day and night with over

95% duty cycle, HAWC has an instantaneous field of view of 2 sr and
surveys 2/3 of the sky every day. It is sensitive to gamma rays from
300 GeV to 100 TeV.

O. Gress, V. Lipunov, F.Balakin, E. Gorbovskoy, V. Kornilov, N.Tyurina, P.Balanutsa,A.Kuznetsov, F.Balakin, V. Vladimirov, D. Vlasenko,
I. Gorbunov,D.Zimnukhov, V.Senik, A.Chasovnikov, A.Pozdnyakov, A.Chasovnikov, V.Topolev, D.Kuvshinov(Lomonosov Moscow State University, SAI, Physics Department),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias IAC),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
H. Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE),
D. Buckley (South African Astronomical Observatory SAAO),
O. Gress, N.M. Budnev, O.Ershova (Irkutsk State University, API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University)

MASTER Global Robotic Net ( http://observ.pereplet.ru, Lipunov et al.,2010,Advances in Astronomy, vol. 2010, 30L)
will not observe IceCube-190819A (Santander et al. GCN 25402
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 ),so as
error-box set faster then Sun and rised later then Sun in MASTER-Amur, MASTER-Tunka,
MASTER-Kislovodsk, MASTER-Tavrida, MASTER-SAAO, MASTER-IAC, MASTER-OAFA.

There is Sy1 PMN_J0948+0022 in current IC190819A error-box,  that was 
also inside IC180908A (Blaufuss et al.GCN23214) error-box (in 5 degrees from IC190819A).
http://observ.pereplet.ru/IC190819/Swift-PMN_J0948+0022.pdf

In IceCube-190819A error-box there was Swift alert in 2017 
https://gcn.gsfc.nasa.gov/other/764204.swift

Also IceCube-190819A error-box includes
* Sources from Fermi LAT catalog are in the list http://observ.pereplet.ru/IC190819/FermiLAT.html
* QSO http://observ.pereplet.ru/IC190819/QSO.html
* galaxies from GLADE cat. http://observ.pereplet.ru/IC190819/GLADE.html

This message may be cited.

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

IceCube has performed a search for additional track-like muon neutrino events arriving
from the direction of IceCube-190819A (https://gcn.gsfc.nasa.gov/gcn3/25402.gcn3
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 ) in a time
range of 2 days centered on the alert event time (2019-08-18 17:34:24.24 UTC to 2019-08-20 17:34:24.24 UTC) during which IceCube was collecting good quality data. Excluding the
event that prompted the alert, zero additional track-like events are found in spatial coincidence
with the 90% containment region of IceCube-190819A. We find that these data are well described by atmospheric background expectations, with a p-value of 1.0. Accordingly, these data would represent a time-integrated muon-neutrino flux upper limit at the alert position assuming an E^-2 spectrum (E^2 dN/dE) at the 90% CL of 3.2 x 10^-5 TeV cm^-2 for this observation period. 90% of events IceCube would detect from a source at this declination with an E^-2 spectrum are approximately between 1 TeV and 10 PeV.

A subsequent search was performed to include the previous month of data (2019-07-19 17:34:24.24 UTC to 2019-08-20 17:34:24.24 UTC). In this case, we report a p-value of 1.0,
consistent with no significant excess of track-like events, and a corresponding time-integrated
muon-neutrino flux upper limit assuming an E^-2 spectrum (E^2 dN/dE) of
 6.4 x 10^-5 TeV cm^-2 at the 90% CL.

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>.

S. Garrappa (DESY-Zeuthen), S. Buson (Univ. of Wuerzburg; UMBC) and�R. 
Angioni�(MPIfR-Bonn) on behalf of the Fermi-LAT collaboration:

We report an analysis of observations of the vicinity of the high-energy 
IC190819A neutrino event (GCN 25402
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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 2019-08-19 17:34:24.24 UTC 
(T0) with J2000 position RA = 148.80 (-3.24,+2.07) deg, Decl. = 1.38 
(-0.75,+1.00) deg 90% PSF containment. One cataloged >100 MeV gamma-ray 
source is located within the 90% IC190819A localization error, at a 
distance of roughly 2.25 deg. This is the object 4FGL J0946.2+0104 (The 
Fermi-LAT Collaboration 2019, arXiv:1902.10045
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 ) associated with the BL 
Lac object�1RXS J094620.5+010459. 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 at gamma-rays.

We searched for the existence of intermediate (months to years) 
timescale emission from a new gamma-ray transient source. Preliminary 
analysis indicates no significant (>5sigma) new excess emission (> 100 
MeV) within the IC190819A 90% confidence localization. Assuming a 
power-law spectrum (photon index = 2.0 fixed) for a point source at the 
IceCube best-fit position, the >100 MeV flux upper limit (95% 
confidence) is < 4.0e-10 ph cm^-2 s^-1 for ~11-years (2008-08-04 / 
2019-08-19 UTC), < 6.8e-8 (< 4.1e-9) ph cm^-2 s^-1 for a 1-day (1-month) 
integration time before T0.

Since Fermi normally operates in an all-sky scanning mode, regular 
monitoring of the region will continue. For this event the Fermi-LAT 
contact person are S. Garrappa (simone.garrappa at desy.de) and S. Buson 
(sara.buson at gmail.com). 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.