LIGO/Virgo G296853

D. Roberts, U. Kolb & M.Morrell (The Open University) reporting on behalf of the PIRATE group:


We observed 34 separate fields within the bayestar skymap of the LIGO/Virgo candidate G296853 using our 0.43m robotic telescope at Teide Observatory, Tenerife, Spain. We acquired over 768 images across 7 nights of observations, all images were obtained using the R filter and 60s exposure length. Initial observations began at 2017-08-10T02:24:29, approximately 17 hours after the initial GCN alert was received. A detailed list of all the fields observed can be found on GraceDB under the EMObservations tab. Preliminary analysis suggests no new transients were detected in any of the observing fields down to a limiting magnitude ~18. Further analysis is ongoing.
-- The Open University is incorporated by Royal Charter (RC 000391), an exempt charity in England & Wales and a charity registered in Scotland (SC 038302). The Open University is authorised and regulated by the Financial Conduct Authority in relation to its secondary activity of credit broking.

M. Jauzac (Durham), G. P. Smith (Birmingham), J. Richard (Lyon), M. 
Bianconi (Birmingham), C. P. L. Berry (Birmingham), W. M. Farr 
(Birmingham), R. Massey (Durham), A. Robertson (Durham), K. Sharon 
(Michigan), A. Vecchio (Birmingham), J. Veitch (Glasgow)

The Gravitationally-lensed Gravitational Wave Hunters collaboration 
report observations of strong-lensing galaxy clusters located within the 
sky localisation of the LIGO/Virgo trigger G296853 (LVC GCN Circ. 21413
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 ).

Following Smith et al. (arXiv:1707.03412
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 ) we searched the skymap for 
strong-lensing galaxy clusters that lie within the 90% credible sky 
localisation.  Abell 2895 was the closest strong-lensing galaxy cluster 
to the peak probability in the skymap.  We observed this cluster with 
MUSE on VLT on the nights of August 9, 14, and 16.  MUSE spans a 1x1 
arcminute field of view with a wavelength range of 4650-9300 Angstroms.

Analysis of these data is ongoing.  Colleagues with complementary data 
are welcome to contact us with a view to collaboration.

We thank the staff at ESO for their outstanding support of our observing 
programmes.

A. Klotz (IRAP/CNRS/UPS), R. Laugier (ARTEMIS/CNRS/UCA/OCA), K. Noysena 
(ARTEMIS/IRAP), M. Boer (ARTEMIS/CNRS/UCA/OCA) report on behalf of the 
TZAC collaboration:

The field of the LVC candidate event G296853 was observed with TCH 
(TAROT-Chile field 1.9 x 1.9 deg2), TCA (TAROT Calern, field 1.9 x 
1.9deg2) and TRE (TAROT La R��union field 4.0 x 4.0 deg2) from Aug. 9, 
2017 at 10h10m11s UT to Aug. 11, 2017, at 1h52m39s under good to 
variable conditions. 122 images lasting 120s each where generated. 
Fields observed at least twice have been checked for new sources with an 
upper limit of R > 17.5. For the other fields the analysis is still in 
progress.

List of fields that were observed, centered on (RA, DEC) :

TCH: 19.242 -20.171, 18.001 -22.035, 20.079 -22.035 from 
2017-08-09T10:10:11 to 2017-08-09T10:36:30 TCA: 19.514 -20.193, 20.369 
-22.057, 18.368 -22.060 from 2017-08-10T00:39:49 to 2017-08-10T02:40:38 
TCH: 18.061 -22.126, 20.074 -22.119, 19.227 -20.264 from 
2017-08-10T02:40:38 to 2017-08-10T04:17:29 TRE: 18.996 -30.232, 20.632 
-26.034, 19.565 -30.232, 20.966 -26.033, 18.161 -34.430, from 
2017-08-10T21:58:50 to 2017-08-11T01:50:39

J. Alvarez-Muniz, F. Pedreira, E. Zas (Univ. Santiago de Compostela, Spain),
K. H. Kampert & M. Schimp (Bergische Universitat, Wuppertal, Germany)
on behalf of the Pierre Auger Collaboration.

In response to the LIGO/Virgo GW trigger G296853
(GCN #21431
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 , T0=2017-08-09 08:28:21.747 UTC):

We searched for Ultra High Energy (UHE) neutrinos with energies
above ~ 1e17 eV in data collected with the Surface Detector (SD) of
the Pierre Auger Observatory in a [-500,500] second interval about
the LIGO-Virgo trigger G296853 as well as 1 day after it.

NO events survived the cuts applied to reject the background due to UHE
Cosmic Rays i.e. NO neutrino candidates were detected.

The field of view (fov) where the SD of Auger is sensitive to UHE neutrinos
(corresponding to inclined directions with respect to the vertical relative
to the ground) was NOT coincident with the LIGO 90% localization region at
the
time T0 of the merger alert. The LIGO 90% localization region maximally
overlapped with the Auger fov for the first time ~ 7 hours after the merger.

The Pierre Auger Observatory is an UHE Cosmic Ray detector
located in the Mendoza Province in Argentina. It consists of an array
of Water Cherenkov detectors spread over a total surface of 3000 km^2
arranged in a triangular grid of 1.5 km side as well as Fluorescence
telescopes and other systems (see 10.1016/j.nima.2015.06.058
for more information).
For neutrino searches from GW events with Auger, please refer to:
https://journals.aps.org/prd/pdf/10.1103/PhysRevD.94.122007

C.M.Copperwheat (LJMU), I.A.Steele (LJMU) reports on behalf of

D.Bersier (LJMU), M.Bode (LJMU), C.Collins (LJMU), M.Darnley (LJMU), D.Galloway (Monash), A.Gomboc (Nova Gorica), S.Kobayashi (LJMU), A. Levan (Warwick), P.Mazzali (LJMU),  C.Mundell (Bath), E.Pian (Pisa), D. Pollacco (Warwick),  D. Steeghs (Warwick), N.Tanvir (Leicester), K. Ulaczyk (Warwick), K.Wiersema (Leicester)

and the GROWTH (Global Relay of Observatories Watching Transients Happen) collaboration.

---

We observed MASTER OT J013646.48-140323.5, originally reported in GCN #21445
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 , on 2017-08-12 at 03:25UT using the SPRAT spectrograph on the Liverpool Telescope.

The spectra we obtain are fairly poor quality due to the proximity of the moon. Using SNID (Blondin & Tonry, 2007, ApJ, 666, 1024) we tentatively classify this transient as a SN Ia or Ib at around 7 days before peak, with a redshift consistent with the distance of the nearby galaxy (170Mpc, as reported in GCN #21445
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 ).

--
------------------------------------------------------
C.M.Copperwheat
Astrophysics Research Institute,
Liverpool John Moores University
------------------------------------------------------
http://telescope.livjm.ac.uk
------------------------------------------------------
Email: c.m.copperwheat@ljmu.ac.uk<mailto:c.m.copperwheat@ljmu.ac.uk>
Tel: +44 (0)151 231 2914
Fax: +44 (0)151 231 2921
------------------------------------------------------

________________________________
Important Notice: the information in this email and any attachments is for the sole use of the intended recipient(s). If you are not an intended recipient, or a person responsible for delivering it to an intended recipient, you should delete it from your system immediately without disclosing its contents elsewhere and advise the sender by returning the email or by telephoning a number contained in the body of the email. No responsibility is accepted for loss or damage arising from viruses or changes made to this message after it was sent. The views contained in this email are those of the author and not necessarily those of Liverpool John Moores University.

A. J. Castro-Tirado (IAA-CSIC and ISA-UMA), C. P��rez del Pulgar and R. 
Mart��n M��rquez (ISA-UMA), A. Castell��n (UMA), M. Jel��nek (ASU-CAS), R. 
Cunniffe, Y. Hu and A. Gonz��lez-Rodr��guez (IAA-CSIC), P. Peseev, G. 
G��mez and A. Alonso (GRANTECAN),  on behalf of a larger collaboration 
report:

In response to the LIGO/Virgo GW Binary Merger Candidate G296853 on Aug 
9, 08:28 UT (GCNC 21431), a mosaic of unfiltered images covering 80% of 
the GraceDB skymap (above -45 in Dec) was taken starting on Aug 10, 
01:30 UT (i.e. 17 hr later) with the wide-field imager at the BOOTES-1 
station located at the ESAt/INTA-CEDEA in Mazag��n (Huelva, Spain), down 
to a R = 12 limiting magnitude. In addition to this, data for several 
selected fields within the skymap center were gathered the same night 
with the 10.4m GTC telescope (+OSIRIS spectrograph) in riz filters down 
to R = 21.5, with the images quality being affected by the nearby full 
moon and the poor transparency due to the dust from Sahara. A more 
detailed analysis of the data is in progress.

J. Y. Liao, X. B. Li, C. K. Li, M. Y. Ge, Y. Huang, S. L. Xiong, Y. Liu,
C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, X. F. Lu, J. L. Zhao,
A. M. Zhang, Y. F. Zhang, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU),
T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu,
S. N. Zhang (IHEP), report on behalf of the Insight-HXMT team:

Insight-HXMT was taking data normally around the LIGO trigger time
(T0=2017-08-09 08:28:21.747 UTC). At T0, more than 95% of the LIGO
localization region was covered by the Insight-HXMT without occultation
by the Earth.

Within T0 +/- 1000 s, no significant events (SNR > 5 sigma) are found
in a search of the Insight-HXMT raw light curves with time scales of
20 ms, 50 ms, 0.2 s and 1 s, respectively.
Only one particle event lasting about 180 s was found at T0-680 s,
which is caused by the orbital environment thus has no relation with
the LIGO event.

With the three typical GRB Band spectral models, three integration time
(1 s, 10 s, and 100 s) and the LIGO localization region, the 3-sigma
upper-limits fluence (0.2 - 5 MeV, incident energy) are reported below:

Band model 1 (alpha=-1.9, beta=-3.7, Ep=70 keV):
1s: 1.4e-07 to 2.6e-07 erg cm^-2
10s: 4.5e-07 to 9.1e-07 erg cm^-2
100s: 1.6e-06 to 3.1e-06 erg cm^-2

Band model 2 (alpha=-1.0, beta=-2.3, Ep=230 keV):
1s: 2.2e-07 to 3.9e-07 erg cm^-2
10s: 7.2e-07 to 1.4e-06 erg cm^-2
100s: 2.5e-06 to 4.6e-06 erg cm^-2

Band model 3 (alpha=-0.0, beta=-1.5, Ep=1000 keV):
1s: 5.2e-07 to 7.5e-07 erg cm^-2
10s: 1.6e-06 to 2.5e-06 erg cm^-2
100s: 5.8e-06 to 8.4e-06 erg cm^-2

All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.

The analysis results presented above are preliminary;
refined results will be reported later.

Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome .

S. Sugita, N. Kawai (Tokyo Tech), M. Serino (RIKEN), H. Negoro (Nihon U.),
S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N.Isobe, R. Shimomukai (JAXA),
T. Mihara, M. Sugizaki, S. Nakahira, W. Iwakiri, M. Shidatsu, M.
Matsuoka (RIKEN),
T. Yoshii, Y. Tachibana, S. Harita, Y. Muraki, K. Morita (Tokyo Tech),
A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Kitaoka, T. Hashimoto (AGU),
H. Tsunemi, T. Yoneyama (Osaka U.),
M. Nakajima, T. Kawase, A. Sakamaki (Nihon U.),
Y. Ueda, T. Hori, A. Tanimoto, S. Oda (Kyoto U.),
Y. Tsuboi, Y. Nakamura, R. Sasaki (Chuo U.),
M. Yamauchi, C. Hanyu, K, Hidaka (Miyazaki U.),
T. Kawamuro (NAOJ),
K. Yamaoka (Nagoya U.)
report on behalf of the MAXI team:

We examined the MAXI/GSC all-sky X-ray images (2-20 keV) obtained
in the orbit and the day after the LVC trigger
G296853 at 2017-08-09 08:28:21.747 UTC (GCN 21431
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 ).

At the trigger time of G296853,
the high-voltage of MAXI/GSC was off,
and it was turned on at T0+1114 sec.
GSC scanned more than 83% of the whole sky in the 92-min orbit,
which includes 92.7% of the 90% region in the bayestar skymap
scanned from 08:49:51 to 09:00:11 UTC (T0+1289 to 1909 sec).
One day image obtained between 08-09 08:49:51 and 08-10 08:09:40 UTC
covers 100% of the 90% region in the bayestar skymap.
No significant new source was found in these images.
The 2-20 keV 1-sigma (3-sigma) averaged upper limits obtained
from the one-orbit and one-day images in the bayestar skymap are
12(36) and 3(9) mCrab, respectively.

If you require information of X-ray flux by MAXI/GSC at specific coordinates,
please contact the submitter of this circular by email.

I. Martinez-Castellanos (University of Maryland, College Park) and
A.J. Smith (University of Maryland, College Park) on behalf of the
HAWC Collaboration:

HAWC performed a follow-up of LIGO trigger G296853. At the time
of the trigger only a small portion (6%) of the probability distribution
overlapped with HAWC field of view (FOV), and it was located at a
large zenith angle where the sensitivity is poorest. The real-time
search was preformed and identified no candidate counterparts.

Additionally we searched for longer duration emission integrating the
next transit of the LIGO contour through HAWC's FOV. The most
probable location transited 1-3hrs after the trigger (~41deg from
zenith at culmination). In total, 52% of the LIGO probability contour
was observed. There were no significant detections (5-sigma).

HAWC is a TeV gamma ray water Cherenkov array located in the
state of Puebla, Mexico. It is sensitive to the energy range
~0.5-100TeV, and monitors 2/3 of the sky every day with an
instantaneous field-of-view of ~2 sr.

Y. Evangelista (INAF/IAPS), E. Del Monte (INAF/IAPS), F. Verrecchia (SSDC
and INAF/OAR), M. Feroci (INAF/IAPS), E. Costa (ASI), A. Trois
(INAF/OA-Cagliari), G. Piano (INAF/IAPS), M. Pilia (INAF/OA-Cagliari), M.
Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Ursi (INAF/IAPS), M.
Cardillo, A. Bulgarelli (INAF/IASF-Bo), C. Pittori (SSDC and INAF/OAR), N.
Parmiggiani (INAF/IASF-Bo), I. Donnarumma (ASI), A. Giuliani (INAF/IASF-Mi),
F. Lucarelli (ASDC and INAF/OAR), G. Minervini (INAF/IAPS), F. Longo (Univ.
Trieste and INFN Trieste), F. Fuschino (INAF/IASF-Bo), M. Marisaldi
(INAF/IASF-Bo and Bergen University), A. Argan (INAF/IAPS),  V. Fioretti
(INAF/IASF-Bo), report on behalf of the AGILE Team:

In response to the LIGO/Virgo GW trigger G296853 (GCN #21431
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 , T0=2017-08-09
08:28:21.747 UTC) we analyzed the AGILE/Super-AGILE (SA) photon-by-photon data
obtaining no significant detection in the 20-60 keV light curve for the
interval T0 +/- 100s with different bin sizes (from 0.05 s to 16 s). The
Super-AGILE FoV covered about 20% of the LIGO 90% localization region,
observed at off-axis angles between 10 and 35 deg.
A 3-sigma upper-limit (UL) in the 20-60 keV energy band has been derived for
an integration time of 1 s, and varies between 2.2 x 10^-8 erg cm^-2 for
10� off-axis position to 7.0 x10^-8  erg cm^-2 at 30� off-axis position.

These measurements were obtained with AGILE observing a large portion of the
sky in spinning mode. Additional analysis of SuperAGILE data is in progress.
This message may be cited.

V.M.  Lipunov, E. Gorbovskoy, V.G.Kornilov, N.Tyurina, V.Shumkov, D.Kuvshinov, 
P.Balanutsa,  O.Gress, A.Kuznetsov, M.I.Panchenko, A.V.Krylov, I.Gorbunov
Lomonosov Moscow State University, Sternberg Astronomical Institute


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

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

N.M. Budnev, O. Gress, K. Ivanov, S.Yazev
Irkutsk State University

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

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

R. Rebolo, M. Serra-Ricart, G. Israelian, N.Lodiu
The Instituto de Astrofisica de Canarias

A. Tlatov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory

MASTER OT J013646.48-140323.5 discovery - PSN in 6.3"E,13.1"S of barred 
spiral PGC005976

During LIGO G296853 area inspection MASTER-SAAO(see Lipunov et al., GCN 
21435
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 ) auto-detection system
(Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 
30L ) discovered possible SuperNova explosion in PGC005976 galaxy
at  position  (RA, Dec) = 01h 36m 46.48s -14d 03m 23.5s on 
2017-08-09.91543 UT  (Gress et al., Atel #10631).
The OT (PSN) unfiltered magnitude is 17.1m (mlim=18.8).
This OT is seen in 4 inspection images. There is no minor planet at this 
place.
We have reference image on 2016-08-27.02894 UT with unfiltered mlim= 
20.3m.

This PSN is located in spiral in 6.3"E,13.1"S of barred PGC005976 with 
Btc=14.82, Vgsr=12113km/s

Corresponding distance is ~ 170 Mpc.

Spectral observations are required.

The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/013646.48-140323.5.png

This message can be citted.

C. Ferrigno (ISDC, University of Geneva, CH)
on behalf of the INTEGRAL group:
V. Savchenko (ISDC, University of Geneva, CH)
S. Mereghetti (IASF-Milano, Italy),
E. Kuulkers (ESTEC/ESA, The Netherlands),
A. Bazzano (IAPS-Roma, Italy), E. Bozzo,
T. J.-L. Courvoisier (ISDC, University of Geneva, CH)
S. Brandt (DTU - Denmark) R. Diehl (MPE-Garching, Germany)
L. Hanlon (UCD, Ireland) P. Laurent (APC, Saclay/CEA, France)
A. Lutovinov (IKI, Russia) J.P. Roques (CESR, France)
R. Sunyaev (IKI, Russia) P. Ubertini (IAPS-Roma, Italy)

The INTEGRAL satellite requires continuous contact between the 
spacecraft and a ground station
for operations and data down-link.
Unfortunately, at the time
of the LIGO/Virgo trigger G296853 (2017-08-09 08:28:21.747 UTC),
there was a scheduled ground-station outage. Therefore, no INTEGRAL data are
available on 2017-08-09 between 06:40:13 and 12:24:39 UTC, preventing 
any investigation of the presence of an electromagnetic signal 
temporally coincident with this gravitational wave trigger.


The field of view of the imaging instruments has not covered the 
high-probability region
of the LIGO event at any time after the trigger and it will not in the 
coming days.
As a consequence, no search of a possible GRB afterglow-like signal is 
foreseeable.

F.Longo (University and INFN, Trieste), N.Omodei, G.Vianello
(Stanford), D.Kocevski (NASA/MSFC) and S.Buson (NASA/GSFC) report on
behalf of the Fermi-LAT team:

We have searched data collected by the Fermi Large Area Telescope
(LAT) for possible high-energy (E > 100 MeV) gamma-ray emission in
spatial/temporal coincidence with the LIGO/Virgo trigger G296853.

At the time of the trigger (T0 =  2017-08-09 08:28:21.747 UTC,
523960106.747 MET), none of the LIGO Bayestar probability map was in
the LAT field of view. Part of the region entered the LAT field of
view 1700 seconds after T0, and we reached 100% cumulative coverage
within ~2.7 ks after the trigger. We define "instantaneous coverage"
as the integral over the region of the LIGO probability map that is
within the LAT field of view at a given time, and "cumulative
coverage" as the integral of the instantaneous coverage over time.

We performed a search for a transient counterpart within the 90%
contour of the LIGO map in the time window from T0  to T0 + 10 ks. We
also performed a search which adapted the time interval of the
analysis to the exposure of each region of the sky. No significant
candidate counterpart was found.  Similarly, the Automated Science
Processing search, which looks for variation in flux from known
sources and for new transients on different time scales (Chiang 2012),
did not detect any new transient consistent  within the 90% contour
of the G296853 map, during a six-hour interval from T0-2hr to T0+4hr.

The Fermi-LAT point of contact for this event is Francesco Longo
(francesco.longo@ts.infn.it).

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.

[GCN OPS NOTE(10aug17): Per author's request, the timestamp in
the second paragraph was changed from "02:01:16.492 UT 523960106.748"
to "08:28:21.747 UTC 523960106.747.]

A. Goldstein (USRA) reports on behalf of the GBM-LIGO Group:
L. Blackburn (CfA), M. S. Briggs (UAH), J. Broida (Carleton College), E.
Burns (NASA/GSFC), J. Camp (NASA/GSFC), T. Dal Canton (NASA/GSFC), N.
Christensen (Carleton College), V. Connaughton (USRA), R. Hamburg (UAH), C.
M. Hui (NASA/MSFC), P. Jenke (UAH), D. Kocevski (NASA/MSFC), N. Leroy
(LAL), T. Littenberg (NASA/MSFC), J. McEnery (NASA/GSFC), R. Preece (UAH),
J. Racusin (NASA/GSFC), P. Shawhan (UMD), K. Siellez (GATech), L. Singer
(NASA/GSFC), J. Veitch (Birmingham), P. Veres (UAH), C. Wilson-Hodge
(NASA/MSFC)

At the G296853 event time, GBM was taking data and viewing the entire
un-occulted sky approximately 67 degrees from Earth center (RA = 66.9, DEC
= +23.4), which includes 49% of the LIGO Bayestar probability map.

There was a single GBM on-board trigger within 1 hour after the event time.
However, this trigger was likely due to a terrestrial gamma-ray flash and
unrelated to the G296853 event. The untargeted ground-based search of GBM
data for short-duration GRBs (Briggs et al., in prep) found a
low-reliability short GRB candidate ~76 minutes after the G296853 event
time, although the localization of this candidate is entirely inconsistent
with the Bayestar map.

The targeted search of the GBM data ([1], [2]) also did not find a
significant gamma-ray signal. This search processes time scales of 0.256 to
8.192 s within 30 s of the LIGO event. No interesting gamma-ray candidate
was found within this time window.

Further analysis and upper limits will be reported later.

[1] L. Blackburn et al. 2015, ApjS 217, 8
[2] A. Goldstein et al. arXiv:1612.02395
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F. Verrecchia (SSDC and INAF/OAR), G. Piano (INAF/IAPS), M. Pilia
(INAF/OA-Cagliari), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A.
Ursi (INAF/IAPS), M. Cardillo, A. Bulgarelli (INAF/IASF-Bo), C. Pittori (SSDC
and INAF/OAR), N. Parmiggiani (INAF/IASF-Bo), I. Donnarumma (ASI), A. Giuliani
(INAF/IASF-Mi), F. Lucarelli (ASDC and INAF/OAR), G. Minervini (INAF/IAPS),
F. Longo (Univ. Trieste and INFN Trieste), F. Fuschino (INAF/IASF-Bo), Y.
Evangelista (INAF/IAPS), M. Marisaldi (INAF/IASF-Bo and Bergen University),
A. Argan (INAF/IAPS), A. Trois  (INAF/OA-Cagliari), V. Fioretti (INAF/IASF-Bo),
report on behalf of the AGILE Team:

In response to the LIGO/Virgo GW trigger G296853 (GCN #21431
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 ), we performed
an analysis of the AGILE Gamma-Ray Imaging Detector (GRID) data on different
timescales. On LIGO trigger time (T0=2017-08-09 08:28:21.747 UTC) the GRID
exposure covered more than the 95% of the LIGO localization region, observed
at off-axis angles between 5 and 55 deg.

An analysis of the data in the energy range 50 MeV - 10 GeV was performed
on timescales from 2 to 100 sec centered at T0.
Preliminary values of 3-sigma upper limits (UL) obtained within the
accessible G296853 localization region are reported below:

from 1.4e-06 to 6.0e-06 erg cm^-2 s^-1 for integration time of 2s
from 1.4e-07 to 5.6e-07 erg cm^-2 s^-1 for integration time of 20s
from 3.1e-08 to 8.4e-08 erg cm^-2 s^-1 for integration time of 100s

These ULs apply to a large fraction of the GRID-exposed LIGO localization
region.

These measurements were obtained with AGILE observing a large portion of
the sky in spinning mode. Additional analysis of AGILE data is in progress.

D.M. Palmer (LANL), S.D. Barthelmy (NASA/GSFC), A. Y. Lien (GSFC/UMBC),
T. Sakamoto (AGU), A. A. Breeveld (MSSL-UCL), A.P. Beardmore (U. Leicester),
D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC),
G. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB),
V.D'Elia(ASDC), S. Emery (UCL-MSSL), P.A. Evans (U. Leicester), 
P. Giommi (ASI), C. Gronwall (PSU), J. A. Kennea (PSU), 
H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), 
F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), 
B. Mingo (U. Leicester), J.A. Nousek (PSU), S.R. Oates (Uni. of Warwick), 
P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), 
C. Pagani (U. Leicester), K.L. Page (U.Leicester), M. Perri (ASDC), 
J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU),
M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/UMCP)
report on behalf of the Swift team:

We report the search results in the BAT data within T0 +/- 100 s of the
LIGO event G296853 (LIGO/VIRGO Collaboration GCN Circ. 21431
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 ), 
where T0 is the LIGO trigger time (2017-08-09T08:28:21.747 UTC).

The center of the BAT FOV at T0 is
RA = 305.082 deg,
DEC = 43.799 deg,
ROLL = 340.755 deg.
At T0, the BAT Field of View (>10% partial coding) covers 0.01% of the integrated
LIGO localization probability. That is, there is no overlap between the BAT 
field of view and the LIGO probability region at T0.

Within T0 +/- 100 s, no significant detections (signal-to-noise ratio >~ 5 sigma) are 
found in the BAT raw light curves with time bins of 64 ms, 1 s, and 1.6 s, respectively. 
Assuming an on-axis (100% coded) short GRB with a typical spectrum in the BAT 
energy range (i.e., a simple power-law model with a power-law index of -1.32, 
Lien & Sakamoto et al. 2016), the 5-sigma upper limit in the 1-s binned light 
curve corresponds to a flux upper limit (15-350 keV) of ~ 1.38 x 10^-7 erg/s/cm^2.

BAT retains decreased, but significant, sensitivity to rate increases for
gamma-ray events outside of its FOV. About 99.88% of the integrated LIGO 
localization probability was outside of the BAT FOV but above the Earth's limb 
from Swift's location, and the corresponding flux upper limits for this region 
are within roughly an order of magnitude of those within the FOV.

V.M.  Lipunov, E. Gorbovskoy, V.G.Kornilov, N.Tyurina, V.Shumkov, D.Kuvshinov, 
P.Balanutsa,  O.Gress, A.Kuznetsov, M.I.Panchenko, A.V.Krylov, I.Gorbunov
Lomonosov Moscow State University, Sternberg Astronomical Institute


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

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

N.M. Budnev, O. Gress, K. Ivanov, S.Yazev
Irkutsk State University

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

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

R. Rebolo, M. Serra-Ricart, G. Israelian, N.Lodiu
The Instituto de Astrofisica de Canarias

A. Tlatov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory

MASTER I  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in OAFA (Argentina) was starting survey on the LVC  G296853 
error-box   2548 sec after notice time and 5501 
sec after trigger time at 2017-08-09 10:00:02 UT. The 5-sigma upper limit 
on our first (180s exposure)  set is about 19.1 mag

The covering map will be available at GraceDB.

Object: Altitude: 71.13 Azimuth: 124.74

Sun: Altitude: -16.84 Azimuth: 261.53

Moon: Altitude: 30.34 Azimuth: 96.86

The object can be observed till sunrise at 2017-08-09 11:19:18 UT.

A. Ursi, M. Cardillo (INAF/IAPS), F. Verrecchia (SSDC and INAF/OAR), M. Tavani
(INAF/IAPS, and Univ. Roma Tor Vergata), G. Piano (INAF/IAPS), M. Pilia
(INAF/OA-Cagliari), C. Pittori (SSDC and INAF/OAR), A. Bulgarelli
(INAF/IASF-Bo), G. Minervini, A. Argan, Y. Evangelista (INAF/IAPS), N.
Parmiggiani, A. Zoli, V. Fioretti (INAF/IASF-Bo), F. Lucarelli (SSDC and
INAF/OAR), I. Donnarumma (ASI), F. Fuschino (INAF/IASF-Bo), M. Marisaldi
(INAF/IASF-Bo and Bergen University),  A. Giuliani (INAF/IASF-Mi), A. Trois
(INAF/OA-Cagliari), F. Longo (Univ. Trieste and INFN Trieste) report on behalf
of the AGILE Team:

In response to the LIGO/Virgo GW event G296853 at T0 = 2017-08-09 08:28:21.747
UTC, a preliminary analysis of the AGILE MiniCALorimeter (MCAL) data found
no event candidates within a time interval covering approximately -/+ 10 sec
from the LIGO T0.

3-sigma ULs were computed for a 1 s integration time on different celestial
positions within the G296853 90% localization region, taking into consideration
the nearest triggered data acquisition (about 14 sec after the LIGO T0),
resulting in typical values of the fluence UL ranging from 6.3e^-7 erg cm^-2
to 7.0e^-7 erg cm^-2 (assuming as spectral model a power law with photon index
1.4). The AGILE-MCAL detector is a CsI detector with a 4-pi FoV, working in
the range 0.4 - 100 MeV. Additional analysis of AGILE data is in progress.

M. Ageron (CPPM/CNRS), B. Baret (APC/CNRS), A. Coleiro (IFIC & APC), D.
  Dornic (CPPM/CNRS), A. Kouchner (APC/Universite Paris Diderot), T.
  Pradier (IPHC/Universite de Strasbourg) report on behalf of the ANTARES
  Collaboration:

  Using on-line data from the ANTARES detector, we have performed a
  follow-up analysis of the recently reported LIGO/Virgo G296853 event
  using the initial LIGO Bayestar probability map at event time.
  The ANTARES visibility at the time of the alert
  together with the 90% contour of the probability map are shown
  in: https://www.cppm.in2p3.fr/~dornic/events/G296853 <https://www.cppm.in2p3.fr/~dornic/events/G296853> (gwantares/
  GW@ANT29). Considering the location probability provided by the LIGO
  collaboration, there is a 62% chance that the GW emitter was in the
  ANTARES field of view.

  No up-going muon neutrino candidate events were recorded within the 90%
  contour during a +/- 500s time-window centered on the G296853 event
  time. The expected number of atmospheric background events in the
  region visible by ANTARES is ~1.0e-2 in the +/- 500s time window. An
  extended search during +/- 1 hour gives no up-going neutrino
  coincidence.

  An estimate of the upper limit on the associated neutrino fluence will
  be sent in a subsequent circular.

  ANTARES, being installed in the Mediterranean Deep Sea, is the largest
  neutrino detector in the Northern Hemisphere.  It 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 a
  large fraction of the Southern sky.

I. Bartos, S. Countryman (Columbia), C. Finley (U Stockholm), E. Blaufuss
(U Maryland), R. Corley, Z. Marka, S. Marka (Columbia) on behalf of the
IceCube Collaboration

We searched IceCube online track-like neutrino candidates (GFU) detected in
a [-500,500] second interval about the LIGO-Virgo trigger G296853. We
compared the candidate source directions of 4 temporally-coincident
neutrinos to the BAYESTAR skymap, with the following parameters:

#            dt[s]     RA[deg]    Dec[deg]      E[TeV]  Sigma[deg]
------------------------------------------------------------------
1.         -310.02        65.9        -5.2        1.11         0.5
2.         -128.45        74.0       -29.2       52.68         0.2
3.          361.60       164.0       -14.6       20.50         0.5
4.          438.49       121.1       -64.8       81.83         2.1


(dt--time from GW in [seconds]; RA/Dec--sky location in [degrees];
E--reconstructed secondary muon energy in [TeV]; Sigma--uncertainty of
direction reconstruction in [degrees])

The analysis found NO COINCIDENT ONLINE TRACK-LIKE NEUTRINO CANDIDATES
detected by IceCube within the 500 second window surrounding G296853 within
the BAYESTAR skymap.

A coincident neutrino-GW skymap has been posted to GraceDB (<
https://gracedb.ligo.org/apiweb/events/G296853/files/
coinc_skymap_initial_icecube.png,0>). A JSON-formatted list of the above
neutrinos can be downloaded from GraceDB at: <https://gracedb.ligo.org/
apiweb/events/G296853/files/IceCubeNeutrinoList.json,0>

In addition, we are performing coincident searches with other IceCube data
streams, including the high-energy starting events (HESE) and Supernova
triggers.  HESE events have typical energies > 60 TeV and start inside the
detector volume, leading to a relatively pure event sample with a high
fraction of astrophysical neutrinos.  The SN trigger system is sensitive to
sudden increases in photomultiplier counts across the detector, which could
indicate a burst of MeV neutrinos.  We will submit separate GCN circulars
if coincident HESE or SN triggers are found.

The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector
operating at the geographic South Pole, Antarctica.  For a description of
the IceCube realtime alert system, please refer to <
http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1610.01814
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 >; for more
information on joint neutrino and gravitational wave searches, please refer
to <http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1602.05411
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 >.

The LIGO Scientific Collaboration and the Virgo Collaboration report:

The gstlal CBC analysis identified candidate G296853 during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2017-08-09 08:28:21.747 UTC (GPS time: 1186302519.747). Virgo (V1) was observing at the time, but with a range only one quarter of that of L1, and data from V1 was not used when estimating this event�s significance.

G296853 is an event of interest because its false alarm rate, as determined by the online analysis, is 7.51e-09 Hz or about one in 4 years, passing our stated alert threshold of ~1/month. The event's properties can be found at this URL:

https://gracedb.ligo.org/events/G296853

This event was also identified in real-time by two other pipelines: Coherent WaveBurst (cWB) and Multi-Band Template Analysis (MBTA).

A sky map is available at this time and can be retrieved from the GraceDB event page:
 * bayestar.fits.gz, a localization generated by BAYESTAR, distributed via GCN notice about 40 minutes after the event. At this time, the BAYESTAR map only uses information from H1 and L1. The 50% credible region spans about 316 deg2 and the 90% region about 1155 deg2, and the posterior probability is mostly confined to the Southern Hemisphere. The mean posterior distance is about 1 Gpc.

The event appears consistent with the merger of two black holes at this time, and there is little chance either component was a neutron star.

Updates on our analysis of this event, including updated localizations which include Virgo data, will be sent as they become available.