IceCube-160731A

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

Swift has observed the field of the IceCube HESE event IceCube-160731A,
"AMON ICECUBE HESE 128290 6888376" (revision 0), utilising the on-board
19-point tiling pattern to cover a region centred on RA,Dec (J2000) =
(215.109, -0.458), 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 03:00:46 and 14:51:52 on 2016 Jul 31 (i.e. from
3.9 ks to 46.5 ks after the neutrino trigger), and covered 2.1
square degrees.

Six X-ray sources are detected in the observations. All of these
correspond either to known X-ray emitters, or to objects catalogued
(e.g. in SIMBAD) and from which X-rays may be expected. Therefore, we
conclude that we have not discovered a transient X-ray event associated
with the IceCube trigger. The 3-sigma upper limit on the count rate in
the rest of the field is 0.01 ct s^-1, which corresponds to a 0.3-10 keV
flux of 4.3e-13 erg cm^-2 s^-1 for a typical AGN spectrum (NH=3e20
cm^-2, Gamma=1.7). Overlaps between the different tiles accounts for 0.5
square degrees: in these regions the 3-sigma upper limit is 0.0071 ct
s^-1, corresponding to 3.1e-13 erg cm^-2 s^-1.

No transient sources were detected in the UVOT data, down to a 3-sigma
upper limit of 18.0, in the u filter.

Details of the six detected X-ray sources are below. All fluxes are
0.3-10 keV and assume the same AGN spectrum as above.

Source 1
========
RA:          14h 22m 46.57s = 215.69403d 	
Dec:         -00d 38' 16.0" = -0.63777d
Error:       4.2 arcsec (90% confidence radius)
Count rate:  (1.7 +/- 0.4) x 10^-2 ct s^-1
Flux:        (7.3 +/- 1.7) x 10^-13 erg cm^-2 s^-1
Notes:       This source is 2.4" from HD 125981 which SIMBAD lists as an
              A0IV star (classified by the Michigan Spectral Survey).
              This detection may not be due to an X-ray source, but due
              to the bright (V = 6.7) stellar optical flux.


Source 2
========
RA:          14h 19m 36.50s = 214.90209d 	
Dec:         -01d 08' 45.3" = -0.14592d
Error:       4.9 arcsec (90% confidence radius)
Count rate:  (1.3 +/- 0.6) x 10^-2 ct s^-1
Flux:        (5.6 +/- 2.6) x 10^-13 erg cm^-2 s^-1
Notes:       This source is 6.5" from [VV2006] J141936.0-010840 which
              SIMBAD lists as a quasar.

Source 3
========
RA:          14h 22m 53.44s = 215.72267d 	
Dec:         -00d 01' 50.7"  = -0.03074d
Error:       5.9 arcsec (90% confidence radius)
Count rate:  (2.2 +/- 0.7) x 10^-2 ct s^-1
Flux:        (9.5 +/- 3.0) x 10^-13 erg cm^-2 s^-1
Notes:       This source is 2.2" from QSO J1422-0001 which SIMBAD lists
              as a quasar, and 3.1" from the known X-ray source,
              3XMM J142253.3-000149. The observed  X-ray flux is
              consistent with the flux in the 3XMM catalogue.

Source 4
========
RA:          14h 22m 53.44s = 215.72267d
Dec:         -00d 36' 00.1"  = -0.60004d
Error:       8.1 arcsec (90% confidence radius)
Count rate:  (6.7 +/- 3.2) x 10^-3 ct s^-1
Flux:        (2.9 +/- 1.4) x 10^-13 erg cm^-2 s^-1
Notes:       This source has been previously detected by Swift
              (1SXPS J142252.8-003553) and the observed flux is
              consistent with the catalogued values.

Source 5
========
RA:          14h 19m 50.15s = 214.95898
Dec:         -00d 06' 45.6" = -0.11266d
Error:       5.5 arcsec (90% confidence radius)
Count rate:  (1.5 +/- 0.6) x 10^-2 ct s^-1
Flux:        (6.5 +/- 2.6) x 10^-13 erg cm^-2 s^-1
Notes:       This source is 2.3" from [VV2006] J141949.9-000644 which
              SIMBAD lists as a quasar.

Source 6
========
RA:          14h 19m 50.15s = 214.61169d
Dec:         -00d 06' 45.6" = 0.24144d
Error:       6.6 arcsec (90% confidence radius)
Count rate:  (1.5 +/- 0.7) x 10^-2 ct s^-1
Flux:        (6.5 +/- 3.0) x 10^-13 erg cm^-2 s^-1
Notes:       This source is 2.3" from 2MASS J14182661+0014283, which
              appears to be a late-type star.

V. Lipunov, E.S. Gorbovskoy,   N.Tyurina, V.Kornilov,
P.Balanutsa,  A.Kuznetsov, D.Kuvshinov, I.Gorbunov
Lomonosov Moscow State University, Sternberg Astronomical Institute

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

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

R.Rebolo, M.Serra, N.Lodieu, G.Israelian
The Instituto de Astrofisica de Canarias

R.Podesta, C.Lopez and F.Podest
Observatorio Astronomico Felix Aguilar (OAFA),
San Juan National University

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

O.Gres, K.Ivanov, S.Yazev, N.M.Budnev, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University

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


MASTER Global robotic Net (MASTER-Net: http://observ.pereplet.ru) received 
IceCube HESE event IceCube-160731A  (AMON ICECUBE HESE 128290 6888376) at 
2016-07-31 01:55:34.5 UT (30s after the EHE_event_time).

At the alert time there was a day at MASTER-Amur, -Tunka, 
-Kislovodsk. It was under the horizont at At MASTER-SAAO ( -42.52deg ) and 
MASTER-IAC ( -14.50). MASTER-OAFA (Argentina) did not received alert due 
to problems with internet.

So we started observations at the following night.

MASTER-Kislovodsk  robotic telescope (Kislovodsk, Russia) was pointed to 
the  IceCube neutrino 160731 event (Taboada et al GCN 19743
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 )  61241  sec 
after trigger time at 2016-07-31 19:23:17 UT. The 5-sigma upper limit has 
been about 19.0 on single (180 sec) and 19.8 on coadd (1260 sec ) 
unfiletered images.

MASTER-IAC  robotic telescope (Teide observatory, Canary Islands/Spain) 
was pointed to the  IceCube neutrino 160731 event  68442  sec after 
trigger time at 2016-07-31 21:25:16 UT. The 5-sigma upper limit has been 
about 20.0 on single (180 sec) and 20.7 on coadd (2160 sec ) 
unfiletered images.

MASTER-OAFA  robotic telescope (Felix Aguilar observatory, Argentina) was 
pointed to the  IceCube neutrino 160731 event  75655  sec after trigger 
time at 2016-07-31 22:55:29 UT. The 5-sigma upper limit has been about 
19.8 on single (180 sec) and 20.5 on coadd (3600 sec ) unfiletered images.

No astrophysical OT detected inseide 2 square degrees around center AMON 
ICECUBE HESE  128290 6888376 error-box.

However we detected and found:


1. MASTER OT J142038.73-002500.1 -  the one point-like 
partical CCD event from AMON  ICECUBE HESE 128290 6888376  event error 
box.


    Date      Time       Expt.        Ra                Dec           Mag
|---------------------|-------|-----------------|-----------------|-------
   2016-07-31 19:26:57     180   (14h 20m 38.73s  -00d 25m 00.1s)    17.9


2. The very bright NGC5584 galaxy  (12.8 mag) presented at Ice Cube error 
box.
Totaly there is 19 Galaxy up to 17 mag at Ice Cube error box.

The  brightest  galaxy at error box  highlighted at out most deep  image:
IAC images (lim = 20.7) is available at 
http://master.sai.msu.ru/static/IceCube160731.png

OAFA image (lim= 20.4) is available at
http://master.sai.msu.ru/static/IceCube160731a.png

3. We checked Swift X-ray sources (Evans et al., GCN 19747
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 ) inside this 
IceCube error-box.

The Source1 (215.69403d, -0.63777d) is a bright known star HD 125981 
(A3IV, Skiff, Catalogue of Stellar Spectral Classifications), MASTER 
doesnt' see variability.

The Source2 (214.90209d, -0.14592d) : there is no OT in MASTER-Net 
database up to 20.7 unfiltered optical limit. There is infrared source 
(AllWise, etc) in 2.2".

The Source3 (215.72267, -0.03074): there is a source with m_OT=19.0 
without changhing with respect to MASTER-Net database. There is a USNO-B1 
star with  B2=19.49, R2=18.93.This star is a GALEX source (possible 
accretion to the white dwarf companion).

The Source4 (215.72267, -0.60004): there is no source in MASTER images 
(20.7 unfiltered optical limit in 68442sec after trigger) and in VIZIER 
database (22m optical limit from POSS images).

The Source 5(214.95898, -0.11266) .  There is a Sloan QSO in 4.1" , no 
change with respect to  MASTER database.

The Source 6 (214.61169, 0.24144). Known bright star (USNO-B1 B2=15.30, 
R2=13.77,I=12.36), also a  Galex source, i.e. possible accretting white 
dwarf)  without variability on MASTER database.

Results: Source 1, 3, 6 not coonected with IceCube event.

Swift XRT sources 2,4,5 are interested.

The message may be cited.

L. P. Singer (NASA/GSFC), M. M. Kasliwal (Caltech), Varun Bhalerao (IUCAA),
Anna Ho (Caltech), Tom Barlow (Caltech), S. B. Cenko (NASA/GSFC),
E. O. Ofek (Weizmann), N. Strotjohann (DESY), A. Franckowiak (DESY),
M. Kowalski (DESY), and G. Tesic (PSU) report on behalf of the
Intermediate Palomar Transient Factory (iPTF) collaboration:

Following the detection and updated localization of the cosmic neutrino
candidate IceCube-160731A
(http://gcn.gsfc.nasa.gov/notices_amon/6888376_128290.amon), we began
searching for optical counterparts using the Palomar 48-inch Oschin
telescope (P48) on 2016-07-31 at 05:22 UT, 3.5 hours after the trigger.

We imaged one field covering an area of 7.1 deg^2 to a limiting magnitude
of R=19.1--19.7. Unfortunately, the EHE localization coincides with an
inoperable CCD. Sifting through candidate variable sources using image
subtraction and standard iPTF vetting procedures, we do not detect any
optical transients close to the IceCube error circle. Two optical
transient candidates are found at 1.1 and 2.0 deg from the neutrino
candidate position:

   name       RA        Dec     sep  mag   t
-----------------------------------------------
iPTF16elf 213.555124 -0.894361 1.1 17.25 3.5
iPTF16elg 212.640918 -0.988094 2.0 18.71 3.75

The two transients are positionally consistent with the nuclei of their
respective host galaxies, CGCG 018-088 at z=0.038 and SDSS
J141033.84-005918.0 at z=0.054.

Positions are in J2000. Separations are in degrees and relative to the
best-estimate IceCube position (214.5440d -0.3347d). Magnitudes are in the
Mould R filter and in the AB system, calibrated with respect to point
sources in SDSS as described in Ofek et al. (2012,
http://dx.doi.org/10.1086/664065
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 ). Times are in hours since the IceCube
trigger.

The diagram http://asd.gsfc.nasa.gov/Leo.Singer/iptf/IceCube-160731.pdf
shows the P48 field in relation to the IceCube 1-sigma error circles.

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

Using data from the ANTARES detector, we have performed a follow-up analysis of the recently reported single extremely high-energy (EHE) neutrino
+IceCube-160731A (AMON IceCube HESE 128290 6888376). Its position is -28.1 degrees below the horizon for ANTARES which could yield to an up-going
+event at the time of the event.

ANTARES is the largest neutrino detector installed in the Mediterranean Sea 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.

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 (50% visibility probability).

This yields a preliminary 90% upper limit on the fluence from a point source of  14 GeV.cm^-2 (2.8 TeV-3.1PeV, energy range corresponding to
+5-95% of the energy distribution) and 27 GeV.cm^-2 (0.4-280 TeV) assuming a E^-2 and E^-2.5 power law spectrum, respectively.

[GCN OPS NOTE(05aug16):  Per operator, the double TITLE-block was removed.]

D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, 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-
160731A (http://gcn.gsfc.nasa.gov/notices_amon/6888376_128290.amon)

No triggered KW event happened from ~5 days before to ~1 day after
the IceCube event. The nearest KW triggers are GRB 160726A
(Frederiks et al, GCN 19733
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 ) and GRB 160802A (Kozlova et al, GCN 19767
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 )

Using Konus-Wind waiting mode data in the interval ��1000 s around the
IceCube trigger (July 31, 2016, 1:55:04 UTC), we estimate an upper
limit (90% conf.) on the 20 ��� 1200 keV fluence to ~7.7x10^-7 erg/cm^2
for a burst with duration less than 2.944 s and with a typical
KW short GRB spectrum (an exponentially cut off power law with
alpha=-0.5 and Ep=500 keV, Svinkin et al. 2016).
For a typical long GRB spectrum (the Band function with alpha=-1,
beta=-2.5, and Ep=250 keV), the corresponding limiting peak flux
is ~5.8x10^-7 erg/cm^2/s (20 ��� 1200 keV, 2.944 s scale).

A plot of the KW waiting mode data can be found at
http://www.ioffe.ru/LEA/IceCube/kw20160731_06904_bg.png


All the quoted values are preliminary.