IceCube-170922A

Claudio Kopper (University of Alberta) and Erik Blaufuss (University of  Maryland) report on behalf of the IceCube Collaboration (http://icecube.wisc.edu/).

On 22 Sep, 2017 IceCube detected a track-like, very-high-energy event with a high probability of being of astrophysical origin. The event was identified by the  Extremely High Energy (EHE) track event selection. The IceCube detector was in a normal operating state. EHE events typically have a neutrino interaction vertex that is outside the detector, produce a muon that traverses the detector volume, and have a high light level (a proxy for energy). 

After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon/50579430_130033.amon), more 
sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 22 Sep, 2017
Time: 20:54:30.43 UTC
RA: 77.43 deg (-0.80 deg/+1.30 deg  90% PSF containment) J2000
Dec: 5.72 deg (-0.40 deg/+0.70 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.

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. Savchenko, C. Ferrigno (ISDC, University of Geneva, CH),
P. Ubertini, A. Bazzano, L. Natalucci (INAF IAPS-Roma, Italy),
S. Mereghetti (INAF IASF-Milano, Italy),
P. Laurent (CEA, Saclay, France),
E. Kuulkers (ESTEC/ESA, The Netherlands)

We have exploited INTEGRAL data to search for a prompt gamma-ray
counterpart of the cosmic neutrino candidate AMON IceCube
IceCube-170922A (GCN 21916
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 ).

At the time of the event (2017-09-22 20:54:30.4 UTC, hereafter T0),
INTEGRAL was operating in nominal mode. The neutrino localization was
at an angle of 111 deg with respect to the spacecraft pointing axis.
For this orientation the best sensitivity is achieved by SPI-ACS or
IBIS/Veto, depending on the GRB spectrum and duration. The orientation
was not optimal for INTEGRAL observation.

We do not detect any significant counterparts and estimate a 3-sigma
upper limit on the 75-2000 keV fluence of 2.8x10^-7 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=500 keV)
occurring at any time in the interval +-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
7.8x10^-7 erg/cm^2/s 8 s time scale in 75-2000 keV energy range.

D. Dornic (CPPM/CNRS), A. Coleiro (APC/Universite Paris Diderot) on behalf of the ANTARES Collaboration:

Using data from the ANTARES detector, we have performed a follow-up analysis of the recently reported single high-energy (EHE) neutrino IceCube-170922A (AMON IceCube EHE 50579430_130033). The reconstructed origin was 14.2 degrees below the horizon for ANTARES.

No up-going muon neutrino candidate events were recorded within three degrees of the IceCube event coordinates during a +/- 1h time-window centered on the IceCube event time. A search on an extended time window of +/- 1 day has also yielded no detection (46% visibility probability).

This yields a preliminary 90% confidence level upper limit on the muon-neutrino fluence from a point source of 15 GeV.cm^-2 over the energy range 3.3 TeV - 3.4 PeV (the range corresponding to 5-95% of the detectable flux) for an E^-2 power-law spectrum, and 34 GeV.cm^-2 (450 GeV - 280 TeV) for an E^-2.5 spectrum.

ANTARES is the largest neutrino detector installed in the Mediterranean Sea, and is primarily sensitive to astrophysical neutrinos in the TeV-PeV energy range.  At 10 TeV, the median angular resolution for muon neutrinos is below 0.5 degrees. In the range 1-100 TeV, ANTARES has the best sensitivity to this position in the sky.

Israel Martinez (University of Maryland) and
Ignacio Taboada (Georgia Tech)
report on behalf of the HAWC collaboration
(https://www.hawc-observatory.org/collaboration/):

On 2017/09/22 20:54:30.43 UTC IceCube detected a track-like,
very-high-energy event with a high probability of being of astrophysical
origin, at RA=77.43d and Dec=5.72d J2000. The up-to-date values were
reported in GCN circular 21916
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 .

Two analyses were performed:

* Search for a steady source.
This analysis was performed on archival data from November 2014 to
June 2017. Assuming a spectral index of -2.5 we searched in a 1.3deg
circle around the IceCube reported location.The maximum significance is
3.5 sigma at RA=76.29deg and Dec=5.04deg. We estimate the number of trials
to be ~130. We set an upper limit 95% CL on gamma rays for this period of:

E^2 dN/dE = 5.62e-15 (E/7TeV)^-0.5 TeV cm^-2 s^-1.

* Search for a transient source.
The event location was not in HAWC's FOV at the time of detection, so
this analysis was performed using data corresponding to the two nearest
transits (MJD 58018.35-59018.60 and 58019.35-59019.60). Using the same
spectral index and search window, the maximum significance is 2.4 sigma at
RA=76.45deg and Dec=5.58deg. We set an upper limit 95% CL on gamma rays
for this period of:

E^2 dN/dE = 2.26e-13 (E/7TeV)^-0.5 TeV cm^-2 s^-1.

HAWC is a very-high-energy gamma-ray observatory located in
Central Mexico at latitude 19 deg North. It operates 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.

A. Keivani (PSU), P.A. Evans (U. Leicester), J.A. Kennea (PSU),  D.B. Fox
(PSU), D.F. Cowen (PSU), J.P. Osborne (U. Leicester), and F.E.
Marshall (GSFC) report on behalf of the Swift-IceCube collaboration:

Swift has observed the field of the IceCube EHE event, IceCube-170922A
(revision 0, https://gcn.gsfc.nasa.gov/notices_amon/50579430_130033.amon),
utilizing the on-board 19-point tiling pattern to cover a region
centred on RA,Dec (J2000) = (77.2866d, +5.7537d), with a radius of
approximately 0.8 degrees. Swift-XRT collected ~800 s per field of PC
mode data per tile. The observations were taken between 00:09:16 UT
and 22:42:08 UT on 2017 September 23 (i.e. from 11.7 ks to 92.9 ks
after the neutrino trigger), and covered 2.1 square degrees.

Nine X-ray sources are detected in the observations. Eight of these
correspond to known X-ray emitters. One object (Source 6) is not
catalogued in X-rays, however it lies 5.7" from PMN J0511+0538 which
is a radio source. The X-ray source position is RA,Dec (J2000) =
(77.8658d, +5.6420d) which is equivalent to:

RA = 05h 11m 27.80s
Dec = +05d 38' 31.2"

with an uncertainty of 7.1" [90% confidence radius]. The mean XRT
count rate is 6.9 (+3.7, -2.8) e-3 ct s^-1. More XRT follow-up
observations have been requested.

The 3-sigma upper limit on the count rate in the rest of the field is
0.0093 ct s^-1, which corresponds to a 0.3-10 keV flux of 3.8e-13 erg
cm^-2 s^-1 for a typical AGN spectrum (NH=3e20 cm^-2, Gamma=1.7).
Overlaps between the different tiles account for 0.5 square degrees:
in these regions the 3-sigma upper limit is 0.0057 ct s^-1,
corresponding to 2.3e-13 erg cm^-2 s^-1.

  Source 1:
  =============
    RA:          76.7226 ( = 05h 06m 53.42s) J2000
    Dec:         +6.1154 ( = +06d 06' 55.4") J2000
    Error:       +4.3 (arcsec, radius, 90% confidence).
    Peak Rate:   5.6e-02 +/- 1.4e-02 ct/sec (0.3-10 keV)
    Peak Flux:   2.3e-12 +/- 5.7e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J050653.3+060648 in the ROSAT/RASSBSC catalogue
    Separation:  7.6" from the XRT source
    Cat Rate:    1.2e-01 +/- 2.0e-02 ct/sec
    Cat Flux:    1.8e-12 +/- 3.0e-13 erg cm^-2 s^-1 (0.3-10 keV)
    A SIMBAD object `TYC  110-755-1' is 3.6" away.

  Source 2:
  =============
    RA:          77.3571 ( = 05h 09m 25.70s) J2000
    Dec:         +5.6924 ( = +05d 41' 32.6") J2000
    Error:       +4.2 (arcsec, radius, 90% confidence).
    Peak Rate:   9.3e-02 +/- 2.1e-02 ct/sec (0.3-10 keV)
    Peak Flux:   3.8e-12 +/- 8.6e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1SXPS J050925.9+054134 in the 1SXPS catalogue
    Separation:  4.7" from the XRT source
    Cat Rate:    3.9e-02 +/- 2.6e-03 ct/sec
    Cat Flux:    1.7e-12 +/- 1.1e-13 erg cm^-2 s^-1 (0.3-10 keV)
    A SIMBAD object `QSO J0509+0541' is 4.8" away.

  Source 3:
  =============
    RA:          77.6614 ( = 05h 10m 38.74s) J2000
    Dec:         +5.9082 ( = +05d 54' 29.5") J2000
    Error:       +5.1 (arcsec, radius, 90% confidence).
    Peak Rate:   1.5e-02 +/- 4.1e-03 ct/sec (0.3-10 keV)
    Peak Flux:   6.2e-13 +/- 1.7e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J051038.6+055432 in the ROSAT/RASSBSC catalogue
    Separation:  3.8" from the XRT source
    Cat Rate:    5.9e-02 +/- 1.4e-02 ct/sec
    Cat Flux:    1.7e-12 +/- 4.0e-13 erg cm^-2 s^-1 (0.3-10 keV)
    A SIMBAD object `2MASS J05103912+0554261' is 6.7" away.

  Source 4:
  =============
    RA:          77.1391 ( = 05h 08m 33.38s) J2000
    Dec:         +5.5188 ( = +05d 31' 07.7") J2000
    Error:       +5.5 (arcsec, radius, 90% confidence).
    Peak Rate:   1.7e-01 +/- 1.3e-01 ct/sec (0.3-10 keV)
    Peak Flux:   7.0e-12 +/- 5.3e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  XMMSL2 J050833.1+053121 in the XMM-NEWTON/XMMSLEWCLN catalogue
    Separation:  13.5" from the XRT source
    Cat Rate:    6.9e-01 +/- 2.9e-01 ct/sec
    Cat Flux:    6.1e-12 +/- 2.6e-12 erg cm^-2 s^-1 (0.3-10 keV)

  Source 5:
  =============
    RA:          77.4264 ( = 05h 09m 42.34s) J2000
    Dec:         +5.7826 ( = +05d 46' 57.4") J2000
    Error:       +5.3 (arcsec, radius, 90% confidence).
    Peak Rate:   1.7e-02 +/- 6.4e-03 ct/sec (0.3-10 keV)
    Peak Flux:   7.0e-13 +/- 2.6e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1SXPS J050942.4+054655 in the 1SXPS catalogue
    Separation:  2.0" from the XRT source
    Cat Rate:    7.2e-03 +/- 1.2e-03 ct/sec
    Cat Flux:    3.1e-13 +/- 5.2e-14 erg cm^-2 s^-1 (0.3-10 keV)
    A SIMBAD object `HD  33326' is 2.1" away.

  Source 7:
  =============
    RA:          77.1531 ( = 05h 08m 36.74s) J2000
    Dec:         +5.2053 ( = +05d 12' 19.1") J2000
    Error:       +6.0 (arcsec, radius, 90% confidence).
    Peak Rate:   2.5e-02 +/- 7.0e-03 ct/sec (0.3-10 keV)
    Peak Flux:   1.0e-12 +/- 2.9e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  XMMSL2 J050836.8+051224 in the XMM-NEWTON/XMMSLEWCLN catalogue
    Separation:  4.7" from the XRT source
    Cat Rate:    9.5e-01 +/- 4.1e-01 ct/sec
    Cat Flux:    9.5e-12 +/- 4.1e-12 erg cm^-2 s^-1 (0.3-10 keV)
    A SIMBAD object `V* V1848 Ori' is 5.8" away.

  Source 8:
  =============
    RA:          77.2410 ( = 05h 08m 57.84s) J2000
    Dec:         +6.4408 ( = +06d 26' 26.9") J2000
    Error:       +5.9 (arcsec, radius, 90% confidence).
    Peak Rate:   3.0e-02 +/- 8.1e-03 ct/sec (0.3-10 keV)
    Peak Flux:   1.2e-12 +/- 3.3e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J050857.4+062633 in the ROSAT/RASSBSC catalogue
    Separation:  9.3" from the XRT source
    Cat Rate:    1.2e-01 +/- 1.8e-02 ct/sec
    Cat Flux:    2.5e-12 +/- 3.9e-13 erg cm^-2 s^-1 (0.3-10 keV)
    A SIMBAD object `1RXS J050857.4+062633' is 7.9" away.
Source 9:
  =============
    RA:          77.4368 ( = 05h 09m 44.83s) J2000
    Dec:         +5.3639 ( = +05d 21' 50.0") J2000
    Error:       +5.7 (arcsec, radius, 90% confidence).
    Peak Rate:   1.4e-02 +/- 5.0e-03 ct/sec (0.3-10 keV)
    Peak Flux:   5.7e-13 +/- 2.0e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J050944.9+052219 in the ROSAT/RASSFSC catalogue
    Separation:  28.9" from the XRT source
    Cat Rate:    2.1e-02 +/- 9.5e-03 ct/sec
    Cat Flux:    2.3e-13 +/- 1.1e-13 erg cm^-2 s^-1 (0.3-10 keV)

P.A. Evans (U. Leicester) A. Keivani (PSU), J.A. Kennea (PSU),  D.B. Fox
(PSU), D.F. Cowen (PSU), J.P. Osborne (U. Leicester), and F.E.
Marshall (GSFC) report on behalf of the Swift-IceCube collaboration:

Fermi-LAT has reported a gamma-ray source (blazar), TXS 0506+056 (3FGL
J0509.4+0541 / 3FHL J0509.4+0542) which is located inside the IceCube-170922A
event error region (Kopper & Blaufuss, GCN Circ. 21916
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 ) and is flaring above 800 MeV
(Tanaka et al., ATEL #10791). This source is
also observed in our Swift-XRT follow-up of IceCube-170922A (Source 2, 1SXPS
J050925.9+054134 in the 1SXPS catalogue), reported previously by Keivani et al. (GCN #21930
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 )

We conducted a further 5 ks observation of this Source with Swift, beginning at
2017 Sep 27 at 18:52 UT (4.95 d after the neutrino event). In these data the
X-ray source has brightened since we the original observations. The current
spectral photon index (gamma) is 2.50 [+0.23, -0.12], similar to the historical
value in 1SXPS: gamma = 2.32 [+0.33, -0.29]
(http://www.swift.ac.uk/1SXPS/1SXPS%20J050925.9%2B054134; Evans et al. 2014). In
our initial observations following the neutrino trigger, gamma was marginally harder
but with large uncertainty: 1.9 [+0.8, -0.7]. The hardness ratio light curve of
the observations taken since the neutrino trigger also shows evidence for
spectral softening between the two epochs, suggesting that the source is
undergoing spectral evolution.

A. Kozlova, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline,
on behalf of the Konus-Wind team, report:

Using Konus-Wind (KW) data, we have performed a search for
a gamma-ray transient around the time of the cosmic neutrino
candidate IceCube-170922A (2017-09-22 20:54:30.43 UT,
hereafter T0; Kopper&Blaufuss, GCN 21916
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 ;
https://gcn.gsfc.nasa.gov/notices_amon/50579430_130033.amon)

No triggered KW event happened from ~1.7 days before and up to ~3.5 days
after T0. The closest waiting-mode event was ~5.5 hours after T0.
Using waiting-mode data within the interval T0  +/- 1000 s,
we found no significant (> ~5 sigma) excess over the background
in both KW detectors on temporal scales from 2.944 s to 100 s in the 
80-1000 keV band.

We estimate an upper limit (90% conf.) on the 10 keV ��� 10 MeV fluence
to 1.0x10^-6 erg/cm^2 for a burst lasting less than 2.944 s and having a
typical KW short GRB spectrum (an exponentially cut off power law with
alpha =-0.5 and Ep=500 keV). For a typical long GRB spectrum (the Band
function with alpha=-1, beta=-2.5, and Ep=300 keV), the corresponding
limiting peak flux is 3.1x10^-7 erg/cm^2/s (10 keV - 10 MeV, 2.944 s 
scale).

All the quoted values are preliminary.

V. Lipunov, E. Gorbovskoy, V.Kornilov,  N.Tiurina, A.Kuznetsov, V.Chazov,
I. Gorbunov, D. Vlasenko, D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov
Lomonosov Moscow State University,SAI

D. Buckley,
South African Astronomical Observatory (SAAO)

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

A. Tlatov, V.Senik, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory

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

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

O. Gres, N.M.Budnev , Yu.Ishmuhametova
Irkutsk State University (ISU)

A. Gabovich, V. Yurkov, Yu. Sergienko
Blagoveschensk Educational State University, Blagoveschensk

MASTER-Tavrida  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Crimea was pointed to the   IceCube-170922A (Kopper  et al. 
GCN #21916
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 ; ) 27 sec after notice 
time and 73 sec after trigger time at 2017-09-22 20:55:43 UT. On our first 
(180s exposure)  set we cleary detected TXS 0506+056   within ICECUBE 
error-box (ra=77.2833 dec=5.75139 r=0.25).
The 5-sigma upper limit has been about 17.5 mag on single and 19.5  on 
coadd images.

Since 2017-09-22 20:55:43 (i.e 73 sec after trigger) till 2017-09-18 we 
have ~ 300 observations provided by MASTER-Tavrida, MASTER-SAAO, 
MASTER-OAFA, MASTER-Kislovodsk and MASTER-Blagoveschensk.

The object zenith distance was 84 degree at a time of first observations 
and it was rise.

Unfortunately, we were extremely busy at this time handling the kiln on 
August 17, 2017, which we detected independent of the Chilean 
telescopes (Abbot et al 2017ApJ...848L..12A; Lipunov et al. 
2017ApJ...850L...1L).

Our telescopes react to 25 IceCube neutrino alerts ( 5874 images!), 
starting with the famous 
neutrino triplet in whose publication we participate and made a decisive 
contribution to the optical inspection (Aartsen et al 2017, A&A, Vol 607, 
A115, DOI: 10.1051/0004-6361/201730620)

Just in case, we report that we have previous, synchronous and subsequent 
optical observations of the ICECube neutrino alert on June  2018.

Just in case, we report that we have precursor and synchronous 
observations  of the   neutrino alert of June  2018 with QSO inside 2 sigma 
error box.

The message may be cited.