IceCube-170312A

Erik Blaufuss (U. of Maryland) reports on behalf of the IceCube Collaboration (http://icecube.wisc.edu/).  

On 03 March, 2017 IceCube detected a track-like, very-high-energy event with a possibility of being of astrophysical origin.  The  event was identified by the High Energy Starting Event (HESE) selection.  The IceCube detector was in a normal operating state.   HESE events  have a neutrino vertex inside of the detector (to reduce background) and have a high light level (a proxy for energy).   

After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon/65274589_129281.amon), more  sophisticated reconstruction algorithms have been applied offline, with the direction refined to:  

Date: 2017-03-12
Time: 13:49:39.83 UT
RA: 305.15 deg (<+/- 0.5  ra uncertainty> deg  90% PSF containment) J2000 
Dec: -26.61 deg (<+/- 0.5 dec uncertainty> deg 90% PSF containment) J2000  

Additionally, after closer inspection of the event details, it shows signs of being consistent with rare atmospheric muon background events that are expected from the realtime event selection.

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

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

Swift has observed the field of the IceCube HESE neutrino,
IceCube-170312A (https://gcn.gsfc.nasa.gov/gcn3/20857.gcn3
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 ), utilizing
the on-board
19-point tiling pattern to cover a region centered on RA,Dec (J2000) =
(304.7300, -26.2380), 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 15:51:22 on 2017-03-12 and 05:04:48 on
2017-03-13 (i.e. from 7.3 ks to 54.9 ks after the neutrino trigger),
and covered 2.1 square degrees.

Five X-ray sources are detected in the observations. One of these
corresponds to a known X-ray emitter, and others are faint objects
well below the RASS limits, therefore we do not consider any of them
to be likely counterparts to the IceCube trigger. 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 4.1e-13 erg
cm^-2 s^-1 for a typical AGN spectrum (NH=3e20cm^-2, Gamma=1.7).
Overlaps between the different tiles accounts for 0.5 square degrees:
in these regions the 3-sigma upper limit is .007 ct s^-1,
corresponding to 2.9e-13 erg cm^-2 s^-1.

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

Source 1
========
RA:          20h 21m 21.41s = 305.33920d 	
Dec:         -26d 01' 32.3" = -26.02565d
Error:       6.3 arcsec (90% confidence radius)
Count rate:  (2.8 [+0.8, -0.7]) x 10^-2 ct s^-1
Flux:        (1.1 [+0.3, -0.2]) x 10^-12 erg cm^-2 s^-1
Notes:       Matches known X-ray source: 1RXS J202121.5-260149 (from
ROSAT/RASSFSC), 16.7102046720847" away.

Source 2
========
RA:          20h 21m 54.52s = 305.47717d
Dec:         -26d 04��� 12.0��� = -26.07000d
Error:       4.9 arcsec (90% confidence radius)
Count rate:  (2.1 +/- 0.6) x 10^-2 ct s^-1
Flux:        (8.6 +/- 2.5) x 10^-13 erg cm^-2 s^-1

Source 3
========
RA:          20h 18m 26.48s = 304.61032d
Dec:         -26d 50��� 24.6��� = -26.84017d
Error:       6.5 arcsec (90% confidence radius)
Count rate:  (1.0 [+0.6, -0.4]) x 10^-2 ct s^-1
Flux:        (4.1 [+2.5, -1.6]) x 10^-13 erg cm^-2 s^-1

Source 4
========
RA:          20h 16m 34.69s = 304.14452d
Dec:         -26d 38��� 56.6��� = -26.64904d
Error:       5.8 arcsec (90% confidence radius)
Count rate:  (1.6 [+0.6, -0.5]) x 10^-2 ct s^-1
Flux:        (6.6 [+2.5, -2.1]) x 10^-13 erg cm^-2 s^-1

Source 5
========
RA:          20h 19m 25.94s = 304.85809d
Dec:         -26d 06��� 09.9��� = -26.10276d
Error:       5.5 arcsec (90% confidence radius)
Count rate:  (6.4 [+3.5, -2.6]) x 10^-2 ct s^-1
Flux:        (2.6 [+1.4, -1.1]) x 10^-12 erg cm^-2 s^-1

[GCN OPS NOTE(17mar17): Per author's request, the Subject line
now includes the event designation and the type of observation.]

N.V.Tyurina, V.M. Lipunov,  E.S. Gorbovskoy, A.S.Kuznetsov,
P.Balanutsa, V.V.Vladimirov, V.V.Chazov, D.Kuvshinov
Lomonosov Moscow State University, Sternberg Astronomical Institute

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

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

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

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

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

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

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

MASTER Global Robotic Net was starting inspection of IceCube HESE neutrino 
alert  IceCube-170312A  (Blaufuss et al. GCN #20857
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 : RA(2000)= 305.15 
-26.61, Triggertime= 2017-03-12 13:49:39.83 UT)
on 2017-03-13 02:06:34UT at MASTER-SAAO (Object: Altitude: 20.35, Sun: 
Altitude: -30.72,Dist. to Moon: 123.282677, Moon disk: 0.997328)
and on 2017-03-14 08:38:51UT at MASTER-OAFA (Object: Altitude: 27.61, Sun: 
Altitude: -25.02,Dist. to Moon: 107.465652, Moon disk: 0.968195).
MASTER-II is 2x4sq.degrees (Lipunov et al., 2010, Advances in Astronomy, 
2010, 30L)

At alert time the state at MASTER observatories are:
MASTER-Amur            Object: Altitude: -61.72 Sun: Altitude: -37.55
MASTER-Tunka           Object: Altitude: -64.60 Sun: Altitude: -25.23
MASTER-Kislovodsk      Object: Altitude: -35.78 Sun: Altitude:  13.57
MASTER-SAAO            Object: Altitude:  11.19 Sun: Altitude:  37.97, 
inspect on13 Mar, mlim=19.2, 20 images
MASTEC-IAC(Tenerife)   Object: Altitude:  13.06 Sun: Altitude:  57.41
MASTER-OAFA(Argentina) Object: Altitude:  84.05 Sun: Altitude:  39.69, 
inspect on 13,19 Mar, mlim=18.5-19.1, 16 images

MASTER auto-detection software doesn't detect optical transient, that can 
be connected with IC alert.

We analized SWIFT Xray sources (Keivani et al., GCN#20890
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 )

1) 20 21 21.41 -26 01 32.3
There is no optical sources up to unfiltered mlim=19.2 during MASTER-SAAO 
inspection of this IC170312 alert on 2017-03-13 02:37:14UT, and mlim=18.5 
(2017-03-14 08:38:51UT), mlim=18.7(2017-03-18 07:38:23UT) in MASTER-OAFA .
There is a faint MASTER optical detection with m<< (unfiltered mlim=19.9) 
in MASTER-IAC database on 2016-07-28 00:13:46UT.
The nearest optical source in VIZIER database is in 5.5", also GALEX 
source(offset is 6.7").

2)20 21 54.52 -26 04 12.0
There is a variable optical source in MASTER database (17.5-18.7 
MASTER-IAC, MASTER-SAAO) with m_OT=18.3 on 2017-03-13 02:59:57.059UT 
(MASTER-SAAO)

There is a GALEX source in 2.6", also optical (USNO,etc) and possible AGN 
(Secrest+, 2015).
http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=&-out.add=_r&-out.add=_RAJ%2C_DEJ&-sort=_r&-to=&-out.max=20&-meta.ucd=2&-meta.foot=1&-c=305.47716666667+-26.07&-c.rs=5

3) 20 18 26.4s -26 50 24.6
Variable optical source in MASTER database :
m_OT=18.7 on 2017-03-13 02:59:57.059UT (MASTER-SAAO)
17.8(2016-10-21 00:34:28.062UT) - 18.8 (2017-03-18 07:34:39.474) 
MASTER-OAFA

4) 20 16 34.69 -26 38 56.6
There is no optical sources brighter then unfiltered mlim=19.2 during 
MASTER-SAAO inspection on 2017-03-13 02:24:33UT,
and in archive images in MASTER-IAC on 2016-07-11 01:42:30UT with 
mlim=20.2
There is no sources in VIZIER

5) 20 19 25.94 -26 06 09.9
There is an optical source in MASTER-SAAO with m_OT~19.3 (mlim=19.5)

There is USNO-B1 star with R1=19.20, B2=20.44 in 1.6", also candidate to 
AGN (Secrest+, 2015).
http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=&-out.add=_r&-out.add=_RAJ%2C_DEJ&-sort=_r&-to=&-out.max=20&-meta.ucd=2&-meta.foot=1&-c=304.85808333333+-26.10275&-c.rs=5


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