IceCube-190730A

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

On 30 July 2019, at 20:50:41.31 UT, IceCube detected a track-like event with high probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_Gold alert stream. The threshold astrophysical neutrino purity for Gold alerts is 50%. This alert has an estimated false alarm rate of 0.68 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/132910_57145925.amon), more 
sophisticated reconstruction algorithms have been applied offline, with the direction refined to: 

Date: 2019/07/30 
Time: 20:50:41.31 UT 
RA: 225.79 ( +1.28 -1.43 deg 90% PSF containment) J2000 
Dec: + 10.47 ( +1.14 -0.89 deg 90% PSF containment) J2000 

The Fermi-LAT catalogue source 4FGL J1504.4+1029, associated with the active galaxy PKS 1502+106, is located within the 50% uncertainty region of the event with an offset of 0.31 degrees from the best-fit neutrino location. PKS 1502+106 is an FSRQ at a redshift of 1.84 also listed in the 3FHL catalog of hard Fermi-LAT gamma-ray sources. 

Given the spatial coincidence with this FSRQ, and the high astrophysical neutrino signalness (approximately 67%), we strongly encourage follow-up observations of the neutrino region of interest and of the FSRQ in particular. 

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

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov,
D. Vlasenko, I.Gorbunov,D.Zimnukhov, V.Senik, A.Chasovnikov, D.Kuvshinov(Lomonosov Moscow State University, SAI, Physics Department),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
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),
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)
observed IceCube-190730A (Stein et al. GCN 25225
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 ) in alert mode.

MASTER-Tavrida robotic telescope  located in Russia (Lomonosov MSU,SAI Crimea astronomical station)
was pointed to the IceCube Alert 190730.87 ( 15h  7m 19.25s , +10d 30m 28.08s, R=0.7552)
errorbox  28 sec after notice time (62 sec after trigger time)
at 2019-07-30 20:51:43 UT, with upper limit 18 mag.
The observations began when error-box altitute = 22 deg, the sun  altitude  was -26.1 deg.

MASTER-IAC robotic telescope  located in Spain (IAC Teide Observatory, Canarias) was 
pointed to the IceCube Alert 190730.87 errorbox  56 sec after notice time (89 sec after trigger time)
  at 2019-07-30 20:52:11 UT, with upper limit up to 20 mag.
Observations started at twilight, began when error-box altitude = 65 deg, the sun  altitude  was -12.4 deg.

The error-box galactic latitude b = -60 deg., longitude l = 98 deg.

MASTER cover map is available 
http://master.sai.msu.ru/static/IC/MASTERcovermapofIC190730A.jpg

AGNs and poss.OT analysis inside error box will be continued.
The message may be cited.

C. Ferrigno, V. Savchenko (ISDC/UniGE, Switzerland)
Maeve Doyle (UCD, Ireland), Alexander Lutovinov (IKI, Moscow, Russia)
J. Rodi (IAPS-Roma, Italy)
A. Coleiro (APC, France)
S. Mereghetti (INAF IASF-Milano, Italy)

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

Using the INTEGRAL all-sky detectors
SPI/ACS (following [1]), IBIS/Veto, and IBIS, we have performed a search 
for a prompt
gamma-ray counterpart of IceCube 190730A, a probable high-energy 
neutrino (GCN 25225
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 ).

At the time of the event (2019-07-30 20:50:41 UTC, hereafter T0),
INTEGRAL was operating in nominal mode. The most likely event
localization was at an angle of 81 deg with respect to the
spacecraft pointing axis. This orientation implies strongly suppressed
(15% of optimal) response of ISGRI, strongly suppressed (31% of
optimal) response of IBIS/Veto, and near-optimal (90% of optimal)
response of SPI-ACS.

The background within +/-300 seconds around the event was very stable
(excess variance 1.1). However, we note the presence of excessive background
variations in the hours surrounding the event, increasing the chance of
spurious counterpart associations, and complicating the preliminary 
background estimation reported here.

We have performed a search for impulsive events in INTEGRAL SPI-ACS
(as described in [2]), IBIS, and IBIS/Veto data. We detect a moderately
significant event (S/N 4.7) at 30s time scale at T0+10 s.
The peak count rate (30s time scale) of the signal in SPI-ACS is 314 cts/s,
which corresponds to 4.7e-8 erg/cm2/s in the 75-2000 keV energy range,
assuming coordinates within the localization region and a typical
long GRB spectrum (Band function with alpha=-1, beta=-2.5, and Ep=300 keV).
This estimate does not account for uncertainties related to the unknown 
event spectrum,
systematic uncertainty on the response (20%), or any dead-time correction.
The non-detection of the event in IBIS would be compatible with a source
at the location of the IceCube neutrino.
We derive a preliminary estimate of the association False Alarm 
Probability (FAP)
at the level of 0.046 (2 sigma), which suggests a likely random 
coincidence.
Further analysis, taking into account accurate FAR measured on the basis 
of the study of the background during days surrounding the event will be 
reported elsewhere.


Given the high chance of a random coincidence of the above event,
we estimate a 3-sigma upper limit on the 75-2000 keV
fluence of 1.8e-07 erg/cm^2 (within the 50% probability containment
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 the typical long GRB spectrum used 
also above,
the derived peak flux upper limit is ~1.6e-07 (5.4e-08) erg/cm^2/s at 1 
s (8 s) time
scale in 75-2000 keV energy range.

 From now on, we will report all the low-S/N excesses detected by our 
pipelines
with preliminary FAP below unity, which are likely background fluctuations.
In addition to the event described above, we find:

 ���� ���� scale (s) | T-T0 (s) | S/N | flux ( x 1e-7 erg/cm2/s) |���� FAP
 ������������ 0.25�������� | -6.6�������� | 3.1 | 4.11 +/-�� 1.22 +/-���� 1.1 | 0.433
 ������������ 0.95�������� |�� 101�������� | 3.5 | 2.31 +/- 0.625 +/- 0.618 | 0.785

In this list "flux" is the derived flux assuming a short-GRB typical 
spectrum
with statistical and systematic uncertainties.
Note that FAP estimates (especially at timescales above 2s) may be 
underestimated
due to non-stationary local background noise.

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

R. Hamburg (UAH) reports on behalf of the Fermi-GBM Team:

For the IceCube high-energy neutrino candidate event 190730A (GCN 25225
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 ),
the reported position:

RA: 225.79 (+1.28 -1.43 deg 90% PSF containment) J2000
Dec: +10.47 (+1.14 -0.89 deg 90% PSF containment) J2000

was occulted by the Earth for Fermi-GBM from approximately 6 minutes
prior until 30 minutes after event time. Therefore, the GBM observations
are not constraining for prompt gamma-ray emission.

Antonio Galvan (IA-UNAM), Israel Martinez-Castellanos (UMD) and Jose Andres
Garcia-Gonzalez (IF-UNAM) reports on behalf of the HAWC collaboration (
http://www.hawc-observatory.org/collaboration/):

On 2019-07-30 at 20:50:41.31 UTC, the IceCube collaboration reported a
track-like event with a moderate probability of being of astrophysical
origin, IceCube-190730A, at RA= 225.79 deg and Dec= +10.47 deg, J2000 (GCN
circular 25225
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 ). In HAWC's sky, the neutrino was at zenith of 60.74  deg
and outside of our field of view. We have performed a search in our
archival data 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  power law with a spectral index of -2.3 we searched in a
1.43 x 1.14 degree rectangle around IceCube's reported location.

The highest significance, 2.38 sigma, was at RA= 226.54 deg, Dec= 10.35 deg
(J2000). Note that there are at least 27 trials in this search, so
post-trials significance is lower and equal to 0.712. We set a
time-integrated upper limit 95% CL on the gamma-ray flux of E^2 dN/dE =
2.418e-13 (E/TeV)^-0.3 TeV cm^-2 s^-1.

* Search for a transient source: Since the events was not in our field of
view at the time reported on the GCN we did a search for the day before and
after as well. The results are the following:

1.) 2019-07-29
Transit starts on 2019-07-29 22:00:36 and ends 2019-07-30 04:06:48 (UTC),
0.75 sigma pre-trials (0 post trials), was at RA= 225.64 deg, Dec= 9.86 deg
(J2000). We set a time-integrated upper limit 95% CL on the gamma-ray flux
of: E^2 dN/dE = 1.013e-11 (E/TeV)^-0.3 TeV cm^-2 s^-1.

2.) 2019-07-30
Transit starts on 2019-07-30 21:56:40 and ends 2019-07-31 04:02:52  (UTC),
1.76 sigma pre-trials (0 post trials), was at RA= 225.51 deg, Dec= 10.73
deg (J2000). We set a time-integrated upper limit 95% CL on the gamma-ray
flux of: E^2 dN/dE = 1.251e-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.

S. Garrappa (DESY-Zeuthen, DE), S. Buson (Univ. of Wuerzburg, DE; UMBC, 
USA)�and D. Gasparrini (ASI SSDC;�INFN Roma Tor Vergata, IT), on behalf 
of the Fermi-LAT collaboration:

We report an analysis of observations of the vicinity of the high-energy 
IC190730A neutrino event (GCN 25225
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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 2019-07-30 20:50:41.31 UTC 
(T0) with J2000 position RA = 225.79 (-1.43,+1.28) deg, Decl. = +10.47 
(-0.89,+1.14) deg 90% PSF containment. One cataloged >100 MeV gamma-ray 
source is located within the 90% IC190730A localization error, at a 
distance of roughly 0.3 deg. This is the object 4FGL J1504.4+1029�(The 
Fermi-LAT Collaboration 2019, arXiv:1902.10045
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 ) associated with the FSRQ 
PKS 1502+106. Based on a preliminary analysis of the LAT data over 
the-timescales of 1-day and 1-week prior to T0, this object is not 
significantly detected at gamma-rays. A preliminary light curve of the 
object is available at the FSSC 
(https://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/source/PKS_1502p106). 
We note that for multiple years PKS1502+106 has been among the top-ten 
highest-fluence blazars in the whole sky when the integrated long-term 
GeV gamma-ray flux is considered. After a long high-activity phase of 
about 4.5 years, its gamma-ray flux has slowly decreased over the past 
year and is currently much lower than what was observed in the previous 
11 years of LAT monitoring.

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 IC190730A 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 < 1.9e-9 ph cm^-2 s^-1 for ~11-years (2008-08-04 / 
2019-07-31 UTC), < 4.6e-9 (< 1.4e-8) ph cm^-2 s^-1 for a 1-month 
(1-week) integration time before T0.

Since Fermi normally operates in an all-sky scanning mode, regular 
monitoring of this source will continue. For this source 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.

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-190730A (https://gcn.gsfc.nasa.gov/gcn3/25225.gcn3
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 ) in a time
range of 2 days centered on the alert event time (2019-07-29 20:50:41.31 UTC to 2019-07-31 20:50:41.31 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% point spread function containment of IceCube-190730A. 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 3.8 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 2 PeV.

A subsequent search was performed to include the previous month of data (2019-06-30 20:50:41.31 UTC to 2019-07-31 20:50:41.31 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
 7.3 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>.

D.Steeghs(1), Y-L.Mong(2), G.Ramsay(5), L.Makrygianni(3),
M.Kennedy(8), D.Galloway(2), K.Ulaczyk(1), J.Lyman(1), K.Ackley(2),
A.Obradovic(2), M.Dyer(3), V.Dhillon(3), P.O'Brien(4), D.Pollacco(1),
E.Thrane(2), S.Poshyachinda(6), E.Palle(7), K.Wiersema(1),
R.Cutter(1), T. Marsh(1), R.West(1), B.Gompertz(1), E.Stanway(1),
A.Casey(2), M.Brown(2), E.Rol(2), J.Mullaney(3), S.Littlefair(3),
E.Daw(3), J.Maund(3), R.Starling(4), R.Eyles(4), S.Tooke(4),
U.Sawangwit(6), D.Mkrtichian(6), S.Awiphan(6), S.Aukkaravittayapun(6),
P.Irawati(6), R.Breton(8), D.Mata-Sanchez(8), T.Heikkila(9),
R.Kotak(9), L.Nuttall (10)
(1) Warwick University; (2) Monash University; (3) Univ. of Sheffield;
(4) University of Leicester; (5) Armagh Observatory & Planetarium;
(6) National Astronomical Research Institute of Thailand;
(7) Instituto de Astrofisica de Canarias; (8) Univ. of Manchester;
(9) University of Turku; (10) University of Portsmouth

report on behalf of the GOTO collaboration:


We carried out observations with the Gravitational-wave Optical
Transient Observer (GOTO), in response to the 190730A IceCube
neutrino event (GCN #25225
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 , #25241
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 ).

We obtained a series of 3x60s exposures using our wide L-band filter
(400-700 nm) with four pointings covering the directional constraint
reported in GCN #25225
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 .  Two sky passes have been completed so far,
starting on 2019 July 31 21:16 UT and 2019 Aug 1 21:15 UT.
Our mean 5-sigma detection limit was g=20.2 mag based on PS1
catalogue calibrators.

Images are processed immediately after acquisition using the GOTOphoto
pipeline. Difference imaging was performed on the median of each
triplet of exposures using recent survey observations of the same
pointings. Source candidates were initially filtered using a trained
classifier and cross-matched against a variety of catalogs, including
the MPC and PS1. Human candidate vetting was performed on those
candidates identified by the classifier. The region was also visually
inspected for any notable detections in case our classifier mis-scored
a detection. No viable optical counterpart candidates were identified.

We investigated the long-term behaviour of the FSRQ source PKS
1502+106 that was noted to be consistent with the directional
constraints. Our sky survey coverage of this sources shows no notable
signs of activity in recent months, including our recent epochs
following the neutrino event.  These findings are consistent with the
ZTF coverage noted in Stein et al. 2019, ATEL 12974. Additional
visits are planned, both scheduled and as part of the sky survey, to
monitor any changes.



=====
GOTO is operated at the La Palma observing facilities of the
University of Warwick on behalf of a consortium including the
University of Warwick, Monash University, Armagh Observatory, the
University of Leicester, the University of Sheffield, the National
Astronomical Research Institute of Thailand (NARIT), the University of
Portsmouth and the Instituto de Astrofisica de Canarias (IAC)
(https://goto-observatory.org)