IceCube-201130A

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

On 20/11/30 at 20:21:46.48 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 1.322 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/134751_31476488.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 20/11/30
Time:  20:21:46.48 UT
RA: 30.54 (+ 1.13 - 1.31 deg  90% PSF containment) J2000
Dec: -12.10 (+ 1.15 - 1.13 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.

There is one Fermi-LAT 4FGL source inside the 90% localization region, 4FGL J0206.4-1151, located at RA 31.6 deg and Dec -11.86 deg (J2000), at a distance of 1.07 degrees from the best-fit location.

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

J. DeLaunay (PSU), D. B. Fox (PSU), A. Keivani (Columbia U.),
J.P. Osborne (U. Leicester), F. Krauss (PSU), T. Gregoire (PSU),
P.A. Evans (U. Leicester), J.A. Kennea (PSU),
H. A. Ayala Solares (PSU) and D.F. Cowen (PSU) report:

Swift observed the field of IceCube 201130A (GCN Circ. 28969
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 ) between 20:52:42
2020 November 30 and 22:53:21 on 2020 November 30, collecting a total of 3.8 ks of
cleaned photon counting (PC) mode data. The observations used a 4-point tiling
pattern with a radius of ~0.3 degrees.

We found 2 X-ray sources, as detailed below. All of these are known X-ray
sources consistent with catalogued fluxes. We therefore do not claim any of
them as the likely counterpart to IceCube 201130A.

The 3-sigma upper limit in the field was in the range 4-7 x 10^-3 ct/sec.

The detected sources were:

Source no:   1
RA (J2000):  30.47644 [degrees] = 02h 01m 54.34s
Dec (J2000): -11.8212 [degrees] = -11d 49' 16.3"
Error:       +4.4 [arcsec, 90% conf. radius]
Count rate (0.3-10 keV): 7.7 (+3.8, -2.9) x 10-3 ct s-1
Flux (0.3-10 keV):       3.3 (+1.6, -1.2) x 10-13 erg cm-2 s-1
Note: This source may be affected by optical loading.
Note: This source matches SIMBAD source HD12460.

Source no:   2
RA (J2000):  30.48834 [degrees] = 02h 01m 57.20s
Dec (J2000): -11.5423 [degrees] = -11d 32' 32.2"
Error:       +2.2 [arcsec, 90% conf. radius]
Count rate (0.3-10 keV): 0.117 (+/-0.013) ct s-1
Flux (0.3-10 keV):       5.0 (+/-0.5) x 10-12 erg cm-2 s-1
Note: This source matches SIMBAD source ICRF J020157.1-113233

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

For the IceCube high-energy neutrino candidate event IceCube-201130A
(GCN 28969
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 ), the reported neutrino location at:

RA: 30.54 (+1.13 -1.31 deg  90% PSF containment) J2000
Dec: -12.10 (+1.15 -1.13 deg 90% PSF containment) J2000

was occulted by the Earth for Fermi-GBM from approximately 10.9 minutes
prior until 24.7 minutes after event time. Therefore, the GBM observations
are not constraining for prompt gamma-ray emission.

S. Garrappa (DESY-Zeuthen), S. Buson (Univ. of Wuerzburg) and M. Kadler 
(Univ. of Wuerzburg) on behalf of the Fermi-LAT collaboration:

We report an analysis of observations of the vicinity of the high-energy 
IC201130A neutrino event (GCN 28969
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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 2020-11-30 at 20:21:46.48 
UT (T0) with J2000 position RA = 30.54 (+1.13, -1.31) deg, Decl. = 
-12.10 (+1.15, -1.13) deg (90% PSF containment). One cataloged gamma-ray 
(>100 MeV) source is located within the 90% IC201130A localization 
region. This is the source 4FGL J0206.4-1151 (4FGL, The Fermi-LAT 
collaboration 2020, ApJS, 247, 33), associated with the flat-spectrum 
radio quasar PMN J0206-1150 (Griffith et al. 1994, ApJS, 90, 179) at 
redshift z = 1.663 (Healey et al. 2008, ApJS, 175, 97). 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).

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 IC201130A 
best-fit position. Assuming a power-law spectrum (photon index = 2.0 
fixed) for a point source at the IC201130A best-fit position, the >100 
MeV flux upper limit (95% confidence) is < 6.3e-10 ph cm^-2 s^-1 for 
~12-years (2008-08-04 to 2020-11-30 UTC), and < 1.4e-8 (< 1.5e-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 source 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.

T. Gregoire (PSU), F. D'Ammando (INAF-IRA Bologna), D. B. Fox (PSU), A.
Keivani (Columbia U.), J.P. Osborne (U. Leicester), F. Krauss (PSU),
P.A. Evans (U. Leicester), J.A. Kennea (PSU), H. A. Ayala Solares (PSU),
D.F. Cowen (PSU) and J. DeLaunay (PSU) report:

Swift observed the location of 4FGL J0206.4-1151, the Fermi-LAT source
closest to the location of IceCube 201130A (IceCube Collaboration; GCN
Circ. 28969
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 ) for 4.0 ks between 14:42 UT and 18:05 UT on 2020 December
1.

The source is detected by XRT at RA, Dec = 31.6094, -11.8440 (degrees)
which corresponds to:

RA (J2000):  02h 06m 26.25s
Dec (J2000): -11d 50' 38.1"

With an uncertainty of 6.4 arcsec (radius, 90% confidence). This
position is 2.8 arcmin from the position of the flat spectrum radio
quasar PMN J0206-1150, that is associated to the gamma-ray source 4FGL
J0206.4-1151 in the Forth Fermi LAT source catalog (Abdollahi et al.
2020, ApJS, 247, 33).

The X-ray spectrum (0.3-10 keV) can be fit by an absorbed power law
model with a HI column density consistent with the Galactic value in the
direction of the source (n_H = 1.7 x 10^20 cm^-2, Ben Bekhti N. et al.,
2016, A&A, 594, A116) and a photon index of 1.7+/-0.7. The corresponding
0.3-10 keV flux (unabsorbed) is 1.6 (+1.1, -0.4) x 10^-13 erg cm^-2
s^-1.

Simultaneous UVOT observations were performed on 2020 December 1 and the
source is detected above 3 sigma in all UVOT filters. The measured
magnitudes (Vega system) are V = 19.48 +/- 0.42, B = 19.68 +/- 0.21, U =
18.99 +/- 0.17, W1 = 19.24 +/- 0.18, M2 = 19.30 +/- 0.11, and W2 = 19.21
+/- 0.11.

V. Savchenko, C. Ferrigno (ISDC/UniGE, Switzerland)
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 combination of INTEGRAL all-sky detectors (following [1]):
SPI/ACS, IBIS/Veto, and IBIS we have performed a search for a prompt
gamma-ray counterpart of IceCube-201130A (GCN 28969
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 ).

At the time of the event (2020-11-30 20:21:46 UTC, hereafter T0),
INTEGRAL was operating in nominal mode. The peak of the event
localization probability was at an angle of 113 deg with respect to
the spacecraft pointing axis. This orientation implies strongly
suppressed (3.8% of optimal) response of ISGRI, strongly suppressed
(30% of optimal) response of IBIS/Veto, and somewhat suppressed (54%
of optimal) response of SPI-ACS.

The background within +/-300 seconds around the event was rather
stable (excess variance 1.2).

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

We do not detect any significant counterparts and estimate a 3-sigma
upper limit on the 75-2000 keV fluence of 3.3e-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 a
typical long GRB spectrum (Band function with alpha=-1, beta=-2.5, and
Ep=300 keV), the derived peak flux upper limit is ~2.8e-07 (1e-07)
erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range.

We report for completeness and in order of FAP, all excesses
identified in the search region. We find: 4 likely background
excesses:

T-T0  | scale | S/N | flux ( x 1e-06 erg/cm2/s) | FAP
7.64  | 0.3   | 3.3 | 0.698 +/- 0.213 +/- 0.223 | 0.263
34.1  | 0.75  | 3.3 | 0.436 +/- 0.134 +/- 0.139 | 0.508
9.37  | 0.15  | 3.3 | 0.989 +/- 0.302 +/- 0.316 | 0.624
-14.9 | 0.35  | 3.1 | 0.605 +/- 0.197 +/- 0.193 | 0.705

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
--

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-201130A (https://gcn.gsfc.nasa.gov/gcn3/28969.gcn3
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 ) in a time
range of 2 days centered on the alert event time (2020-11-29 20:21:46.48 UTC to 2020-12-01 20:21:46.48 UTC) during which IceCube was collecting good quality data. Excluding the
event that prompted the alert, two additional track-like events are found in spatial coincidence
with the 90% containment region of IceCube-201130A. We find that these data are consistent with atmospheric background expectations, with a p-value of 0.07. We accordingly derive a time-integrated muon-neutrino flux upper limit at the alert position of E^2 dN/dE = 1.4 x 10^-4 TeV cm^-2 at 90% CL, under the assumption of an E^-2 power law. 90% of events IceCube would detect from a source at this declination with an E^-2 spectrum are approximately between 10 TeV and 10 PeV.

A subsequent search was performed to include the month of data prior to the alert event (2020-10-31 20:21:46.48 UTC to 2020-12-01 20:21:46.48 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
1.5 x 10^-4 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>.

Hugo Ayala (Penn State) reports on behalf of the HAWC
collaboration (http://www.hawc-observatory.org/collaboration):

On 2020/11/30 20:21:46 UTC, the IceCube collaboration reported a
track-like very-high-energy event  that has a high probability of
being an astrophysical neutrino, IceCube-201130A. Location is at
RA: 30.54 (+1.13/-1.31 deg  90% PSF containment) J2000
Dec: -12.10 (+1.15/-1.13 deg 90% PSF containment) J2000
(GCN circular 28969
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 ).

We performed two types of analyses for the follow-up. The first is for
a steady source in archival data and the second is a search for a
transient source. We assume a power-law spectrum with an index of -2.3
for both analyses.

Search for a steady source in archival data:
The archival data spans from November 2014 to June 2019. We searched
inside the reported IceCube error region.
The most significant location, with p-value 5.23e-3 (1.38e-1 post-trials),
is at RA 29.22 deg, Dec -12.71 deg (��0.21 deg 68% containment) J2000.
We set a time-integrated 95% CL  upper limit on gamma rays at the
maximum position of:

E^2 dN/dE = 5.46e-13 (E/TeV)^-0.3 TeV.cm^-2.s^-1

Search for a transient source.

Since the event was not in our field of view at the time reported,
we report the combined result for the transits before and after the
IceCube event.

Data acquisition started on 2020/11/29 05:47:42 UTC and ended
2020/12/01 06:08:38 UTC.
The most significant location, with p-value S.SS  (S.SS post-trials),
is at RA 29.62 deg, Dec +10.92 deg (��0.92 deg 68% containment) J2000.
We set a time-integrated 95% CL upper limit at the position of
maximum significance of:

E^2 dN/dE = 1.87e-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.

Sven Weimann (Ruhr University Bochum), Robert Stein (DESY), Simeon Reusch (DESY) and Anna Franckowiak (DESY/Ruhr University Bochum) report:

On behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations: 
We observed the localization region of the neutrino event IceCube-201130A (Lagunas Gualda et al., GCN 28969
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 ) with the Palomar 48-inch telescope, equipped with the 47 square degree ZTF camera (Bellm et al. 2019, Graham et al. 2019). We started observations in the g- and r-band beginning at 2020-12-01 03:30 UTC, approximately 7.1 hours after event time and observed in two consecutive nights. We covered 4.5 sq deg, corresponding to 98.3% of the reported localization region. This estimate accounts for chip gaps. Each exposure was 300s with a typical depth of 21.0 mag.
 
The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts (Masci et al. 2019). AMPEL (Nordin et al. 2019, Stein et al. 2020) was used to search the alerts database for candidates. We reject stellar sources (Tachibana and Miller 2018) and moving objects, and apply machine learning algorithms (Mahabal et al. 2019).

No counterpart candidates were detected.

ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY, Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan; IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia.
ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341.
GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949.
Alert distribution service provided by DIRAC@UW (Patterson et al. 2019).
Alert database searches are done by AMPEL (Nordin et al. 2019).
Alert filtering is performed with the AMPEL Follow-up Pipeline (Stein et al. 2020).

T. Gregoire (PSU), F. D'Ammando (INAF-IRA Bologna), D. B. Fox (PSU),
A. Keivani (Columbia U.), J. P. Osborne (U. Leicester), F. Krauss
(PSU), P. A. Evans (U. Leicester), J. A. Kennea (PSU), H. A. Ayala
Solares (PSU), D. F. Cowen (PSU) and J. DeLaunay (PSU)

We report on continuing Swift observations of the flat spectrum radio
quasar PMN J0206-1150, associated with the gamma-ray source 4FGL
J0206.4-1151 (Abdollahi et al. 2020, ApJS, 247, 33), the Fermi-LAT
source closest to the location of IceCube 201130A (IceCube
Collaboration; GCN Circ. 28969
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 ). After the first Swift observation
performed on 2020 December 1 (ATel #14240, GCN Circ. 28979
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 ), the
source has been observed again by Swift between 20:39 UT on 2020
December 2 and 11:24 UT on 2020 December 3 for a total of 3.9 ks.

The source has been detected by XRT with a net count rate of (2.2 +/-
0.9)e-3 cps. As a comparison, the net count rate of the source on
December 1 was (3.1 +/- 0.9)e-3 cps, showing a mild decrease of the
source activity in X-rays.

Assuming a photon index of 1.7, as observed on December 1, and fitting
the X-ray spectrum with an absorbed power law model with a HI column
density consistent with the Galactic value in the direction of the
source (n_H = 1.7 x 10^20 cm^-2, Ben Bekhti N. et al., 2016, A&A, 594,
A116), we obtain a 0.3-10 keV flux (unabsorbed) of 4.1 (+2.4, -2.0) x
10^-14 erg cm^-2 s^-1.

Simultaneous UVOT observations were performed on 2020 December 2-3 and
the source is detected above 3 sigma in all UVOT filters, except for
the V filter. The measured magnitudes (Vega system) are V > 19.46, B =
19.60 +/- 0.18, U = 18.72 +/- 0.16, W1 = 18.93 +/- 0.15, M2 = 19.17
+/- 0.10, and W2 = 19.21 +/- 0.12. Differently from the X-ray band, a
moderate brightening has been observed from U to M2 filters on
December 2-3 with respect to December 1.

In GCN Circ. 28979
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  [and ATel #14240] we wrongly reported that the X-ray
source detected by XRT was 2.8 arcmin from the position of PMN
J0206-1150, while it should be 2.8 arcsec.

Sasada, M., Nakaoka, T., Akitaya, H. (Hiroshima U.),
Utsumi, Y. (Stanford U./SLAC)

We report our optical and near-infrared imaging observations
for the IceCube high-energy neutrino candidate event,
IceCube-201130A (GCN Circ. 28969
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 ).

We selected 11 radio sources from our BROS catalog
(Itoh et al. 2020, ApJ 901, 3) including radio sources 3C 57, and
4FGL J0206.4-1151 (ATel #14235) and imaged each of them
in R and J bands with the Kanata telescope using the HONIR
imaging and spectropolarimeter
(Akitaya et al. 2014, Proc. SPIE 9147, 91474O). We present
magnitudes in the AB system. The upper limits are the 5-sigma
detection limits. Each magnitude is calibrated by nearby stars
listed in PanSTARRS for R, and in 2MASS catalogs for J.

BROS_J0206.4-1150 was also observed by Swift (GCN Circ. 28994
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 ).
They reported mild decrease of source activity in X-rays and a
moderate brightening from U to M2 filter on December 2-3 with
respect to December 1. Our observations on 2020-12-01 10:14UT
and 2020-12-02 09:40UT in the R band shown below were not able
to confirm this brightness trend by large photometric error.

BROS_J0201.9-1132 (3C 57) RA:30.488288, Dec:-11.542607
MJD    R    J
59184.41560, 15.89+/-0.04, 16.04+/-0.04
59185.39238, 15.91+/-0.03, 16.09+/-0.04
59186.41061, 15.93+/-0.04, 16.12+/-0.05
59187.54670, 15.98+/-0.09, 16.19+/-0.06
59191.44694, 15.92+/-0.04, 16.08+/-0.03

BROS_J0206.4-1150 (4FGL J0206.4-1151) RA:31.608821, Dec:-11.844354
59184.42646, 19.5+/-0.3, >18.7
59185.40333, 19.8+/-0.3, >18.4
59191.46875, 19.6+/-0.3, >19.2

BROS_J0204.3-1157 RA:31.084787, Dec:-11.960983
59184.43740, 18.4+/-0.2, 17.2+/-0.1
59185.42506, 18.6+/-0.1, 17.3+/-0.1
59186.42147, 18.46+/-0.08, 17.32+/-0.08
59191.45787, 18.41+/-0.08, 17.37+/-0.09

BROS_J0203.7-1250 RA:30.942665, Dec:-12.846279
59184.45914, >19.8, >18.9

BROS_J0200.7-1258 RA:30.193870, Dec:-12.967430
59184.44823, >20.0, >19.0

BROS_J0158.8-0932 RA:29.721666, Dec:-9.539370
59184.48092, >19.7, >18.8

BROS_J0150.5-1212 RA:27.637326, Dec:-12.214537
59184.51353, >18.3, >18.3

BROS_J0155.9-0945 RA:28.988929, Dec:-9.759423
59184.47004, >20.3, >19.4
59185.44682, >20.4, >19.0

BROS_J0200.8-0936 RA:30.215875, Dec:-9.606755
59184.49623, >18.5, >17.5

BROS_J0202.0-1451 RA:30.523600, Dec:-14.863539
59184.52442, 17.9+/-0.2, 17.0+/-0.1
59191.47962, 17.8+/-0.1, 16.91+/-0.07

BROS_J0202.8-0930 RA:30.713050, Dec:-9.514563
59184.50265, >19.9, >19.0