IceCube-190221A

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

On February 21st, 2019, IceCube detected a track-like, very-high-energy event with a high probability of being of astrophysical origin. The event was identified by the High Energy Starting Event (HESE) track selection. The IceCube detector was in a normal operating state. HESE tracks have a neutrino interaction vertex inside the detector and produce a muon that only partially traverses the detector volume, and have a high light level (a proxy for energy). �We encourage follow-up observations.

After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon/66688965_132229.amon), more 
sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2019/02/21 
Time: 08:25:40 UT
RA: 268.81 [-1.8,+1.2] (deg �90% PSF containment) J2000
Dec: -17.04 [-0.5,+1.3] (deg 90% PSF containment) J2000

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, N.Tyurina, V.Kornilov, D.Vlasenko, V.Vladimirov, D.Zimnukhov,
A.Kuznetsov, P.Balanutsa, V.Senik, A. Chasovnikov, V.Topolev, D.Kuvshinov (Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C. Lopez, C.Francile, F. Podesta (Observatorio Astronomico Felix Aguilar OAFA),

H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE)

O. Gress, N.M. Budnev, O.Ershova, Yu.Ishmuhametova (Applied Physics Institute,Irkutsk State University),

V. Yurkov, A. Gabovich, Yu. Sergienko, D. Kobcev (Blagoveschensk Educational State University),

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Institutode Astrofisica de Canarias),

D. Buckley (South African Astronomical Observatory),

A. Tlatov,  D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),


MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)
located in Argentina (OAFA observatory of San Juan National University)
was pointed to the  IC190221A  (The IceCube Collaboration  GCN 23918
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 )
17 sec after notice time (47 sec after trigger time) at 2019-02-21 08:26:26 UT.

The 5-sigma upper limit ~19 mag (180s exposition), we have 9 expositions.
Also we have 4 images of the part of IC error-box in time ntervall 
2019-02-21 08:01:49-08:14:20UT (11 minutes befor neutrino alert)
during Fermi trigger inspection .

The full analysys of ICECUBE error-box (RA: 268.81 [-1.8,+1.2], Dec: -17.04 [-0.5,+1.3] ) will be continued.

The error box center galactic latitude b = 3.5 deg., longitude l = 11.7deg.
The observations started when error-box altitude was 33deg.
The sun  altitude  is -23.0 deg.
The moon (96 % bright part) was 43 deg. above the horizon. The distance between  moon and  object was 91

The message may be cited.

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

We have searched the Fermi Gamma-ray Burst Monitor data
for a gamma-ray counterpart to IceCube-190221A (The
IceCube Collaboration, GCN 23918
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 ). The neutrino position
(RA, Dec) = (268.81, -17.04) was Earth-occulted for
Fermi-GBM from about T0-700 s to T0+1200 s. We therefore
cannot set any limits on impulsive emission.

S. Cutini (INFN Perugia), S. Buson (Univ. of Wuerzburg), S. Garrappa (DESY Zeuthen),  C. C.  Cheung (NRL) and S. Ciprini (INFN Roma2) 

on behalf of the Fermi-LAT collaboration:

We report an analysis of observations of the vicinity of the very high-energy IC190221A neutrino event (GCN 23918
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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 2019-02-21 08:25:40 UT (T0) with J2000 position RA = 268.81 [-1.8,+1.2] Dec: -17.04 [-0.5,+1.3]  90% PSF containment. The neutrino's position is close to the Inner Galaxy. In the preliminary 8-year Fermi-LAT source list (available here: https://fermi.gsfc.nasa.gov/ssc/data/access/lat/fl8y/ <https://fermi.gsfc.nasa.gov/ssc/data/access/lat/fl8y/>), we find two >100 MeV gamma-ray sources located within the 90% IC190221A localization error. These are  unassociated objects FL8Y J1758.6-1622 and FL8Y J1750.4-1723, at a distance of approximately 1.1 deg and 1.2 deg, respectively.

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 (0.1 - 300 GeV) within the IC190221A 90% confidence localization. Assuming a power-law spectrum (photon index = 2 fixed) for a point source at the IceCube best-fit position, the >100 MeV flux upper limits (95% confidence) are < 1.7e-9 ph cm^-2 s^-1 for ~10.5-years (2008-08-04 / 2019-01-03 UTC) integration time, < 1.2e-8   ph cm^-2 s^-1 for a 1-month 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 persons are S. Cutini (sara.cutini at pg.infn.it <http://pg.infn.it/>) and S. Buson (sara.buson at gmail.com <http://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.

A. Keivani (Columbia U.), P. A. Evans (U. Leicester), D. B. Fox (PSU), J.
A. Kennea (PSU),  D. F. Cowen (PSU), J. P. Osborne (U. Leicester), F. E.
Marshall (GSFC), Marcos Santander (U. Alabama), Miguel Mostafa (PSU), and
Hugo Ayala (PSU) report:


The Neil Gehrels Swift Observatory observed the field of the IceCube HESE
astrophysical neutrino candidate IceCube-190221A (revision 1,
https://gcn.gsfc.nasa.gov/gcn3/23918.gcn3
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 ) beginning Feb 21.6 UT (6.55h
after the neutrino detection), utilizing its onboard 19-point tiling
pattern to cover a region centered on R.A., Dec. (J2000) = 268.81d,
-17.04d, with a radius of approximately 0.8 degrees; estimated
90%-containment radii for this event are 0.5 deg to 1.8 deg depending on
position angle. Earlier observations targeting the pre-revision
localization R.A., Dec. (J2000) = 267.3650d, -16.9379d beginning ~2 hours
after the neutrino arrival time have also been executed, and are not
reported here.

Swift-XRT collected ~400 s per field of PC mode data per tile between 14:58:40
UT and 21:34:12 UT on 21 February (6.55h to 13.14h after the neutrino
detection) over 2.1 square degrees. Data have been reduced using the
analysis approach and software routines of Evans et al. 2014 (ApJS, 210,
8).

Three X-ray sources are detected in these data, two of which likely
correspond to the stars HD 162561 (2MASS J17521921-1658102) and TYC
6254-1118-1 (2MASS J17531121-1725423). The third X-ray source is located at
R.A. 17h 53m 50.24s, Dec. -16d 18��� 45.1��� (J2000) with an uncertainty of
4.8��� (90%-confidence radius) and matches the known X-ray source XMMSL2
J175349.9-161846 from the XMM-Newton slew survey (3.7��� distance). The
source���s mean observed XRT count rate is 3.9 (+1.5, -1.2) e-2 ct s^-1,
which is 1.7-sigma below the XMMSL2 catalog flux.

The 3-sigma upper limit on the count rate of any point-like counterpart
over the rest of the tiled region is 0.02 ct s^-1, which corresponds to a
0.3-10 keV flux of 8.0e-13 erg cm^-2 s^-1 for a typical AGN spectrum
(nH=3e20 cm^-2, Gamma=1.7).

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-190221A (https://gcn.gsfc.nasa.gov/gcn3/23918.gcn3
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 ) in a time
range of 2 days centered on the alert event time (2019-02-20 08:25:40.00 UTC to 2019-02-22
08:25:40.00 UTC) during which IceCube was collecting good quality data. Excluding
the event that prompted the alert, 2 additional track-like events are found in spatial coincidence
with the 90% PSF containment of IceCube-190221A. We find that these 2 additional events are
well described by atmospheric background expectations, with a p-value of 0.08. Accordingly,
these data would represent a time-integrated muon-neutrino flux upper limit assuming an E^-2
spectrum (E^2 dN/dE) at the 90% CL of 2.71 x 10^-4 TeV cm^-2 for this observation period.

A subsequent search was performed to include the previous month of data (2019-01-21
08:25:40.00 UTC to 2019-02-22 08:25:40.00 UTC). In this case, we report a p-value of 1.0,
consistent with no significant excess of track events, and a corresponding
time-integrated muon-neutrino flux upper limit assuming an E^-2 spectrum (E^2 dN/dE) at the 90% CL of 3.5 x 10^-4 TeV cm^-2.

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>

J. Rodi, A. Bazzano, L. Natalucci, F. Panessa, P. Ubertini
(IAPS-Roma, Italy)
V. Savchenko, C. Ferrigno, E. Bozzo, T. Courvoisier
(ISDC/UniGE, Switzerland)
E. Kuulkers (ESTEC/ESA, The Netherlands)
C. Sanchez (ESAC/ESA, Spain)
S. Mereghetti (INAF IASF-Milano, Italy)
J. Chenevez, S. Brandt (DTU, Denmark)
R. Diehl, A. von Kienlin (MPE, Germany)
D. Gotz, Ph. Laurent, A. Goldwurm
(DRF/Irfu/DAp Saclay/CEA, France)
A. Coleiro (APC, France)
L. Hanlon, A. Martin-Carrillo (UCD, Ireland)
J.-P. Roques, E. Jourdain, P. von Ballmoos (IRAP, France)
A. Domingo, J. M. Mas-Hesse (CAB/CSIC-INTA, Spain)
A. Lutovinov, R. Sunyaev (IKI, Russia)


Using INTEGRAL we have performed a search for a prompt gamma-ray
counterpart of the cosmic neutrino candidate IceCube-190221A
(GCN 23918
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 ).

At the time of the event (2019-02-21 08:25:40 UTC, hereafter T0),
INTEGRAL was operating in nominal mode. The peak of the neutrino
localization probability was at an angle of 20 deg with respect to
the spacecraft pointing axis. This orientation implies strongly
suppressed response of IBIS/Veto and SPI-ACS, but near-optimal
response of IBIS out of its coded Field of View.

The background within +/-300 seconds around the event was very
stable.�� We do not detect any significant counterparts and estimate
a 3-sigma upper limit on the 75-2000 keV fluence of 5.2e-07 erg/cm^2
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
~4.7e-07 (1.7e-07) erg/cm^2/s at 1 s (8 s) time scale in 75-2000
keV energy range.