LIGO/Virgo G284239

The LIGO Scientific Collaboration and Virgo Collaboration report:

The oLIB Burst analysis (Lynch et al, arXiv:1511.05955
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 ) identified
candidate G284239 during real-time processing of data from LIGO
Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at
2017-05-02 22:26:07.910 UTC (GPS time: 1177799185.910).

G284239 is a low-significance short-duration burst candidate. Its
false alarm rate, as determined by the online analysis, is 1.26e-07 Hz
or about 4 per year. The event's properties can be found at this URL:

https://gracedb.ligo.org/events/G284239

No other GW event candidates were identified within a 300 s window
before or after G284239.

A sky map, LIB_skymap.fits.gz, is available to be retrieved from the
GraceDB event page.  This is the preferred sky map at this time.
The 50% confidence region covers 1029 squares degrees and the 90%
confidence region covers 3593 square degrees.

The GCN Notice and Circular were delayed by more than 16 hours
due to a technical problem, now resolved.

Updates on our analysis of this event will be sent as they become
available.

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 G284239.  
We compared the candidate source directions of 1 temporally-coincident 
neutrinos to the LIB_SKYMAP skymap, with the following parameters:

#            dt[s]     RA[deg]    Dec[deg]      E[TeV]  Sigma[deg]
------------------------------------------------------------------
1.            4.38       136.0        -2.9        0.79    28.2


(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 G284239 
within the LIB_SKYMAP skymap.

A coincident neutrino-GW skymap has been posted to GraceDB 
(<https://gracedb.ligo.org/apiweb/events/G284239/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/G284239/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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 >.

A. Ursi (INAF/IAPS), F. Verrecchia (SSDC/ASDC and INAF/OAR), M. Pilia
(INAF/OA-Cagliari), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), C.
Pittori (ASDC and INAF/OAR), G. Minervini (INAF/IAPS), F. Lucarelli (ASDC
and INAF/OAR), A. Bulgarelli, V. Fioretti, A. Zoli, N. Parmiggiani, F.
Fuschino (INAF/IASF-Bo), M. Cardillo, G. Piano, A. Argan, Y. Evangelista
(INAF/IAPS), I. Donnarumma (ASI), M. Marisaldi (Bergen University and
INAF/IASF-Bo), 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 G284239 at T0 = 2017-05-02
22:26:07.910
UTC, a preliminary analysis of the AGILE-GW fast data processing procedure
found no AGILE MiniCALorimeter (MCAL) event candidates within a time
interval
covering +/-50 s from the LIGO T0.

MCAL data acquisition was collected between 15 s and 2 s before the LVC T0.
A preliminary analysis shows no significant transient candidate event, at
different time scales. 3-sigma ULs were computed for a 1 s integration
time,
on different celestial positions within the accessible G284239 localization
region. They vary from a minimum of 6.6e-7 erg cm^-2 to a maximum of
1.7e-6 erg cm^-2, assuming a single power law spectrum with photon index
1.4.
The AGILE-MCAL instrument is a CsI calorimeter with a 4PI FoV, sensitive in
the energy range 0.4 - 100 MeV. Additional analysis of AGILE data is in
progress.

V. Savchenko (ISDC, University of Geneva, CH)
on behalf of the INTEGRAL group:
S. Mereghetti (IASF-Milano, Italy),
C. Ferrigno ((ISDC, University of Geneva, CH),
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)

We investigated serendipitous INTEGRAL observations carried out at the
time of the LIGO/Virgo burst candidate G284239.  The satellite was
pointing at RA=294.829 Dec=17.726, far from the high-probability area of 
LIGO
localization. For the full LIGO 90% confidence region the best upper
limit is set by the anti-coincidence shield of the spectrometer on board
of INTEGRAL (SPI/ACS).

The INTEGRAL Burst Alert System (IBAS) did not identify any unusual
transients in coincidence with the LIGO/Virgo trigger. The IBAS
inspects both ISGRI Field of View and all-sky SPI-ACS light curve.

We investigated the SPI-ACS, IBIS/Veto, and IBIS/ISGRI light curves
between -500 and +500 s from the trigger time (2017-05-02 22:26:07
UTC) on temporal scales from 0.1 to 100 s, and found no evidence for
any deviation from the background.  We estimate combined typical
3-sigma upper limits of 3.7e-7 erg/cm2 (75-2000 keV) for 8s duration
assuming Band model parameters alpha=-1, beta=-2.5, and E_ peak = 300
keV.  To derive a limit for a typical short burst with 1 s duration,
we use a harder cutoff power law spectrum with a photon index of -0.5
and an Epeak = 500 keV. We find a limiting fluence of 1.5e-7 erg/cm2
(75-2000 keV) at 3 sigma c.l. These limits assume a perpendicular
direction of the burst to the INTEGRAL pointing direction, optimal for
SPI-ACS sensitivity. However the extent of the region with optimal
response depends on the possible source spectrum: we perform a
detailed calculation only for a cutoff powerlaw spectrum with a photon
index of -0.5 and an Epeak = 500 keV. We estimate that 60% of the LIGO
localization probability is covered with a range of sensitivity from
optimal for SPI-ACS (mentioned above) to 50% worse than optimal. The
90% LIGO confidence region includes a small area for which the SPI-ACS
sensitivity is unusually strongly suppressed. The region in which
SPI-ACS sensitivity is reduced more than by factor 3 contains about
10% of LIGO localization probability.

G. Minervini (INAF/IAPS), C. Pittori (ASDC), M. Pilia (INAF/OA-Cagliari),
M. Cardillo (INAF/IAPS), F. Verrecchia (ASDC and INAF/OAR),
M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), G. Piano (INAF/IAPS),
A. Bulgarelli, V. Fioretti, A. Zoli, N. Parmiggiani (INAF/IASF-Bo),
F. Lucarelli (ASDC and INAF/OAR), P. Munar-Adrover (INAF/IAPS), A.
Argan, Y. Evangelista (INAF/IAPS), I. Donnarumma (ASI), F. Fuschino, 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 event G284239 (GCN #21060
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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 = 2017-05-02 22:26:07.910 UT) the GRID had no
exposure of the the LVC localization region (LR) mainly due to Earth
occultation. The GRID large-FoV covered about 25-35% of the LR on
integrations
from about T0-100s to T0, and from T0+300s to T0+400s following the T0,
with
off-axis angles between 20 and 70 deg, approximately.

An analysis of the GRID data in the energy range 50 MeV - 10 GeV was
performed on timescales from 2 to 100 sec centered at T0-50s. Preliminary
minimum and maximum values of 3-sigma upper limits obtained within the
accessible G284239 LR are reported below:
from 1.4e-07 erg cm^-2 s^-1 to 6.5e-07 erg cm^-2 s^-1 for an integration
time
of 20s, and from 3.2e-08 erg cm^-2 s^-1 to 2.5e-07 erg cm^-2 s^-1 for an
integration time of 100s.

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

A. Y. Lien (GSFC/UMBC), S.D. Barthelmy (NASA/GSFC), D.M. Palmer (LANL),
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), 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),
D. Malesani (DARK/NBI), 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 G284239 (LIGO/VIRGO Collaboration GCN Circ. 21060
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 ),
where T0 is the LIGO trigger time (2017-05-02 22:26:07.910 UTC).

The spacecraft was slewing from T0-29.92 s to T0+127.08 s.
The BAT pointing position at T0 is
RA = 159.716 deg,
DEC = -22.885 deg,
ROLL = 266.818 deg.
The BAT Field of View (>10% partial coding) covers 0.02% of the integrated
LIGO localization probability.

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 4-sigma upper limit in the 1-s binned light
curve corresponds to a flux upper limit (15-350 keV) of ~ 6.9 x 10^-8 erg/s/cm^2.
Moreover, so far no event-by-event data are found within T0 +/- 100 s.

BAT retains decreased, but significant, sensitivity to rate increases for
gamma-ray events outside of its FOV. About 54.19% 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.

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

The TAROT network of telescopes has observed part of the error box of
the GW trigger G284239 (GCN 21060
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 ). The observations
took place at TCA (TAROT OCA Calern observatory, France), TCH (TAROT
Chile, ESO La Silla Observatory), and TRE (TAROT Les Makes Observatory,
La R��union Island, France) during the respective night of May 3-4, 2017, and will continue the next night.
The field of view of TCA and TCH is 1.86�� (square), and
4.2�� for TRE. 5 fields have been observed by TCA, 5 for TCH and 9 for
TRE, resulting in a total of 179 sq. deg. explored in the error box.
The exposures lasted 120s with no filter, resulting in
approximate limiting magnitude of R < 18 for TCA and TCH (depending on
the conditions and Moon) and 17 for TRE. The list of the fields is given
below.

Analysis is underway.

List of fields:
Site	     Field# 	RA          DEC		UTC Start time
'Tarot_Calern'	0	18:07:47    -21:10:48	2017-05-03T23:39:00.974
'Tarot_Calern'	1	18:08:32    -23:2:24	2017-05-03T23:43:20.974
'Tarot_Calern'	2	18:16:37    -23:2:24	2017-05-04T00:11:50.974
'Tarot_Calern'	3	18:18:40    -24:54:0	2017-05-04T00:16:10.974
'Tarot_Calern'	4	18:00:21    -19:19:12	2017-05-03T23:32:10.974
'Tarot_Chili'	0	18:07:47    -21:10:48	2017-05-04T02:08:41.869
'Tarot_Chili'	1	18:08:32    -23:2:24	2017-05-04T02:13:01.869
'Tarot_Chili'	2	18:16:37    -23:2:24	2017-05-04T02:17:21.869
'Tarot_Chili'	3	18:18:40    -24:54:0	2017-05-04T02:21:41.869
'Tarot_Chili'	4	18:00:21    -19:19:12	2017-05-04T02:01:51.869
'Tarot_Reunion'	0	18:18:29    -22:47:59	2017-05-03T18:51:47.549
'Tarot_Reunion'	1	18:31:53    -26:59:59	2017-05-03T18:58:17.549
'Tarot_Reunion'	2	18:00:16    -22:47:59	2017-05-03T17:54:47.549
'Tarot_Reunion'	3	17:53:50    -18:35:59	2017-05-03T18:01:17.549
'Tarot_Reunion'	4	18:11:33    -18:35:59	2017-05-03T18:07:47.549
'Tarot_Reunion'	5	18:13:01    -26:59:59	2017-05-03T18:14:17.549
'Tarot_Reunion'	6	18:32:52    -31:11:59	2017-05-03T18:20:47.549
'Tarot_Reunion'	7	17:53:12    -14:23:59	2017-05-03T18:27:17.549
'Tarot_Reunion'	8	17:40:58    -10:11:59	2017-05-03T18:33:47.549
'Tarot_Reunion'	9	18:40:16    -35:23:59	2017-05-03T18:40:17.549

D. Kocevski, N. Omodei, G. Vianello, and J. Racusin 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 G284239

The Fermi gamma-ray space telescope was passing through the South Atlantic Anomaly (SAA) at the time of the trigger (T0 =  2017-05-02 22:26:07.9 UTC). During SAA passages both the LAT and the Gamma-ray Burst Monitor (GBM) do not collect data due to the high charged particle background in this region. The LAT resumed data taking upon exiting the SAA at roughly T0 + 1485 s. At that time the Fermi-LAT had an instantaneous coverage of ~26% at the time of the trigger, and reached 100% cumulative coverage within ~9 ks. 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, and no significant new sources are found. 

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.

Energy flux upper bounds between 100 MeV and 1 GeV for this search vary between 1.4e-10 ��� 2.2e-9 [erg/cm^2/s].

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.

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

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

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

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

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-Kislovodsk  observed part of the G284239 error field 
synchronousely by 
very  wide field cameras (MASTER-VWFC 2x380 square degrees) with m_lim=11 
mag on  the  single images and m_lim=12.5 1 minute started from trigger 
time.

MASTER-Tunka started inspection of LIGO G284239 event (A.Weinstein  et al. 
GCN21060
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 ) 7478 s after Notice Time on 2017-05-03 16:34:32UT.

MASTER II  robotic telescope 
located in SAAO was starting survey on the LVC  GWB 170502.93 error-box
   19358 sec after notice time and 77992 
sec after trigger time at 2017-05-03 20:05:59 UT.

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in IAC was starting survey on the LVC  GWB 170502.93 error-box
   26505 sec after notice time and 85139 
sec after trigger time at 2017-05-03 22:05:06 UT.

Covering area is the 1142 square degrees. 
The covering map is available at 
http://master.sai.msu.ru/static//ligo/db/G284239/151//img/ligo_master_2017-05-05-10-15-24.eb.180.0.png

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

HAWC was operating and our real-time all-sky GRB monitoring analysis was running at the time of the G284239 event. At the time of the event, the HAWC detector was oriented at (��, ��) = (100.2��, 19.0��), local zenith. 28% of the LIGO/Virgo CWB probability contour fell within our observable field (0-45 deg zenith angle).

We perform a real-time search for counts above the steady-state cosmic-ray background using 4 sliding time windows (0.1, 1, 10, and 100 seconds) shifted forward in time by 10% of their width over the course of the entire observing period. Within each time window, we search the HAWC sky within 45 degrees of zenith using 2.1 deg x 2.1 deg square bins shifted by ~0.1 deg along the directions of Right Ascension and Declination. This analysis is optimized for detecting ~100 GeV photons and is sensitive to the most fluent GRBs. It did not report any significant post-trials events near the time of the LIGO trigger.

After the LIGO trigger was reported, we re-analyzed data the in the time the trigger time on 3 timescales (1, 10, 100 sec) with a reduced threshold to account for the reduced number of trials. No significant candidates were identified.

Additionally, we searched for longer duration emission, integrating from the time of the trigger to the time when the overlapping 90% containment LIGO contour left our FOV. We did not find a significant excess in these ~1-2hr observations, which covered 28% of the probability space. Approximately 12 hr after the trigger, the high longitude portion of the contour transited through our field of view, and these locations were search integrating the whole ~6hr of their transit. No significant excess was observed. In total 63% of the of the LIGO contour was observed within 24hrs of the trigger. HAWC has a 5-sigma point-source sensitivity to a flux >1 TeV of ~2x10^-11/cm^2/s, about ~1 ���crab unit���, for a single transit observation.

HAWC is a TeV gamma ray water Cherenkov array located in the state of Puebla, Mexico that monitors 2/3 of the sky every day with an instantaneous field-of-view of ~2 sr.

L.P. Xin (NAOC), J.Y. Wei (NAOC), X.H. Han (NAOC), C. Wu (NAOC),
S. Antier (LAL), N. Leroy (LAL), X.M. Meng (NAOC), L. Huang (NAOC),
Y. Xu (NAOC), H.B. Cai (NAOC), J. Wang (NAOC), X.M. Lu (NAOC),
Y.L. Qiu (NAOC), J.S. Deng (NAOC), L. Cao (NAOC), S. Wang (NAOC),
L. Jia (NAOC), S.C. Zou (NAOC), S.F. Liu (NAOC), Q.C. Feng (NAOC),
H.L. Li (NAOC), D.W. Xu (NAOC), Y.J. Xiao (NAOC), W.L. Dong (NAOC),
Y.T. Zheng (NAOC), E.W.Liang (GXU), X.G.Wang (GXU), Y.G. Yang (HBNU),
B. Cordier (CEA), S.N. Zhang (NAOC), D. Dornic (CPPM), B.B. Wu (IHEP),
D. Turpin (IRAP), A. Klotz (IRAP), C.Lachaud (APC),
on behalf of the SVOM Gravitational Astronomy group report:

We observed about 2400 square degree (6 sky regions) of the skymap
of the advanced LIGO trigger G284239, with SVOM/Mini-GWAC, at Xinglong
Observatory of NAOC equipped with U9000 camera (FOV~400 square
degree/camera).
SVOM/Mini-GWAC comprises 12 wide field angle cameras (aperture=7cm),
working with unfiltered band. The observations are operated in time-series
mode, taking one exposure in 15 seconds (10s exposure + 5s readout).
The limit magnitude is ~12 mag in R band. We estimate a 22.0% prior
probability that these 6 regions contain the true location of the
source.

The coordinates of the 6 regions and observation time are list following:
start-obs(UTC)  end-obs(UTC)    Ra      Dec     Camera_ID
2017-05-05 12:18:07 2017-05-05 14:09:34 06:35:33.2 +70:03:11   C3
2017-05-05 14:17:02 2017-05-05 20:09:33 17:41:40.8 +30:05:48   C3
2017-05-05 12:15:52 2017-05-05 14:07:41 06:44:38.4 +49:45:43   C4
2017-05-05 14:15:38 2017-05-05 20:09:05 17:45:33.4 +10:00:59   C4
2017-05-05 12:10:29 2017-05-05 17:09:26 09:15:43.9 +69:29:34   C5
2017-05-05 19:59:14 2017-05-05 20:09:17 11:56:29.8 +69:27:40   C5
2017-05-05 12:10:29 2017-05-05 17:09:36 09:21:17.0 +50:29:41   C6
2017-05-05 17:10:50 2017-05-05 20:04:52 12:01:27.8 +50:23:40   C6
2017-05-05 12:11:12 2017-05-05 20:09:24 16:15:56.4 +29:39:59   C7
2017-05-05 12:45:41 2017-05-05 20:09:30 16:16:57.1 +10:13:56   C8

The covering map is available at:
http://svom.bao.ac.cn/svomgwpub/skymap/G284239_skymap_miniGWAC.png
(svom:gw2017@svom).

The first image was taken 2.4 days after the event trigger. The delay
is due to the bad weather.
No any significant transient is found in our online pipeline. The
image analysis is ongoing in detailed processing with our offline
pipeline to search for any transient candidate.

Sujay Mate (IIT Bombay),  Ajay Vibhute (IUCAA), Varun Bhalerao (IIT Bombay), Dipankar Bhattacharya (IUCAA), Sukanta Bose (IUCAA), Gulab Chand Dewangan (IUCAA), Ranjeev Misra (IUCAA), Sanjit Mitra (IUCAA), A R Rao (TIFR), Tarun Souradeep (IUCAA), Santosh Vadawale (PRL), on behalf of the Astrosat CZTI team report:

We carried out offline analysis of data from AstroSat CZTI in a 100 second window centred on the G284239 trigger time, UT 2017-05-02 22:26:07.910, to look for any hard X-ray flash. CZTI is a coded aperture mask instrument that has considerable effective area for about 29% of the entire sky. Based on the pointing direction of AstroSat at the time of the GW event and the LIB skymap provided by LVC (LIB_skymap.fits.gz,0), the sky visible to CZTI has 13.8% probability of containing the EM counterpart.

CZTI data were de-trended to remove orbit-wise background variation. We then searched data from the four independent, identical quadrants to look for coincident spikes in the count rates. Searches were undertaken by binning the data in 0.1s, 1s and 10s respectively. Statistical fluctuations in count rates were estimated by using data from 8 neighbouring orbits. We selected confidence levels such that the probability of a false trigger in this 100s window is 10^-4. We do not find any evidence for any hard X-ray transient in this window. We model the source with a band function using standard parameters, with alpha = -1, beta = -2.5 and E_peak = 300 keV. The sensitivity of CZTI varies with direction. We weight the sensitivity by the baystar probability density map to calculate upper limits on any coincident emission from the source. In the 30-200 keV, the upper limits for source fluence are 5.27e-07 ergs/cm^2, 1.29e-06 ergs/cm^2 and 2.84e-06 ergs/cm^2 for search timescales of 0.1, 1, and 10 seconds respectively. The corresponding flux upper limits for the three timescales are 5.27e-06, 1.29e-06, and 2.84e-07 ergs/cm^2/sec respectively. 

Plots showing CZTI sensitivity as a function of direction for this event can be found at https://gracedb.ligo.org/apiweb/events/G284239/files/G284239_CZTI_limits.pdf

S. Sugita, N. Kawai (Tokyo Tech), M. Serino (RIKEN), H. Negoro (Nihon U.),
S. Ueno, H. Tomida, N. Isobe, M. Ishikawa, Y. Sugawara (JAXA),
T. Mihara, M. Sugizaki, S. Nakahira, W. Iwakiri, M. Shidatsu, M.
Matsuoka (RIKEN),
T. Yoshii, Y. Tachibana, S. Harita, K. Morita, Y. Muraki (Tokyo Tech),
A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Kitaoka (AGU),
H. Tsunemi, T. Yoneyama (Osaka U.),
M. Nakajima, A. Sakamaki, T. Kawase (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.),
K. Yamaoka (Nagoya U.),
T. Kawamuro (NAOJ)

We examined the MAXI/GSC all-sky X-ray images (2-20 keV) obtained
in the orbit and the day after the LVC trigger
G284239 at 2017-05-02 22:26:07.910 UTC (GCN 21060
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 ).

MAXI/GSC scanned more than 88%
of the whole sky in the 92-min orbit, which includes 81.2% of the
90% regions in the LIB_skymap.
One day image covers 100% of the 90% regions
in the LIB_skymap.
No significant new source was found in these images.
The upper limits for the X-ray flux are different depending
on the part of the sky.
For instance, typical 2-20 keV 1-sigma (3-sigma) upper limits obtained
from the one-orbit and one-day images are
11(33) mCrab and  4(12) 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.

M. de Naurois on behalf of the H.E.S.S. collaboration

The H.E.S.S. array of imaging atmospheric Cherenkov telescopes was used to carry out follow-up observations of 4 regions within the LIB map of the GW trigger G284239.
Observations started May 4, at 02:01 UT and resulted in a sensitivity (above ~100 GeV) of about 20% of the flux from the Crab nebula at 5 sigma throughout the covered region. A preliminary analysis did not reveal significant gamma-ray emission in any of the observed fields (within a field-of-view of ~2deg radius around the coordinates given below). Further analyses of the data are on-going.

The following region-of-interests (ROIs) were observed:

ROI 1:
Target RA	18h01m14s
Target Dec	-17��44'24''
Duration: 22 min

ROI 2:
Target RA	18h27m50s
Target Dec	-28��42'36''
Duration: 28 min 

ROI 3: 
Target RA	18h14m29s
Target Dec	-19��36'0''
Duration: 28 min 

ROI 4: 
Target RA	18h34m7s
Target Dec	-30��48'36''
Duration: 19 min

H.E.S.S. is an array of five imaging atmospheric Cherenkov telescopes for the detection of very-high-energy gamma-ray sources and is located in the Khomas Highlands in Namibia. It was constructed and is operated by researchers from Armenia, Australia, Austria, the Czech Republic, France, Germany, Ireland, Netherlands, Japan, Poland, South Africa, Sweden, UK, and the host country, Namibia.

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

Konus-Wind (KW) was observing the whole sky at the time of the LIGO
event G284239 (2017-05-02 22:26:07.910 UTC, hereafter T0; LIGO/VIRGO
Collaboration GCN Circ. 21060
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 ).

No triggered KW event happened from ~6 days before to ~2 days
after T0. The closest waiting-mode events are ~35 hours before and
~28 hours after T0. Using waiting-mode data within the interval
T0 +/- 100 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.

We estimate an upper limit (90% conf.) on the 10 keV ��� 10 MeV fluence
to 8.8x10^-7 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 3.3x10^-7 erg/cm^2/s (10 keV - 10 MeV, 2.944 s scale).

All the quoted values are preliminary.

Sheng Yang (INAF-OAPd, UC Davis), Stefano Valenti(UC Davis), David Sand (TTU), Leonardo Tartaglia (TTU, UC Davis), Enrico Cappellaro(INAF-OAPd), Dan Reichart, Josh Haislip (UNC) report on behalf of the Gravitational Wave Follow-Up by DLT40.

We report the observation of 58 galaxies within the LVC error region for the GW trigger G284239 using the GW LIB localization map.We selected 85 galaxies from the GWGC catalogue within 95.0% of the trigger error region, within a distance of 40.0 Mpc, brighter that -17.5 mag and at a Declination < 20 degree. 58 of those galaxies have been observed using the Prompt 5 telescope and are part of the ongoing DLT40 search. They represent the 3.3% of all galaxies within 40.0 Mpc in the Glade catalogue within the LVC error region for the GW trigger and contains 13.3% of all B band luminosity of those galaxies. We started to observe these sample of galaxies on 2017-5-2 and monitored them for 2 weeks after the GW trigger. No interesting transients have been identified down to a limit magnitude of 19.

Below follow the list of galaxies observed:
Name RA(J2000) DEC(J2000) Dist(Mpc) BMAG KMAG
NGC6384 263.1007 7.0603 25.94 -21.26 -24.5418
IC4837A 288.8173 -54.1325 33.42 -21.15 -24.474
NGC6788 291.7071 -54.9513 34.56 -21.09 -24.1729
NGC6181 248.0877 19.8259 33.57 -20.73 -23.9578
IC4837 288.808 -54.6659 33.42 -20.72 -20.383
NGC6368 261.7978 11.5436 30.48 -20.62 -23.2311
NGC7049 319.7449 -48.5632 29.92 -20.61 -25.1338
NGC6887 304.3219 -52.7968 30.06 -20.49 -23.5189
NGC6868 302.4754 -48.3796 26.79 -20.45 -24.8229
NGC6810 295.8931 -58.6557 23.12 -20.42 -24.1399
IC4889 296.3133 -54.3442 29.24 -20.33 -24.2199
NGC6861 301.8312 -48.3703 28.05 -20.29 -24.5317
NGC7029 317.967 -49.2838 38.37 -20.23 -24.38
IC4797 284.1237 -54.3059 28.05 -20.23 -24.1707
NGC6851 300.8932 -48.2845 36.14 -20.13 -24.0209
IC4946 305.992 -43.9953 34.67 -20.12 -23.9688
ESO183-030 284.2327 -54.5457 33.42 -20.11 -24.292
NGC7041 319.1349 -48.3636 25.7 -20.06 -23.8377
NGC6909 306.9121 -47.027 35.48 -20.04 -23.5259
IC4839 288.8919 -54.6266 35.11 -20.02 -23.4762
NGC6870 302.5452 -48.2871 33.42 -19.9 -23.673
NGC6509 269.8555 6.287 27.67 -19.81 -22.476
NGC7007 316.3662 -52.5519 34.67 -19.75 -23.7408
ESO231-017 286.1934 -47.8487 35.14 -19.62 -23.204
IC4901 298.5957 -58.7139 17.86 -19.61 -22.4144
NGC6890 304.5756 -44.8071 31.19 -19.52 -23.4431
NGC6875A 302.9827 -46.1441 29.11 -19.52 -22.3472
NGC6889 304.7221 -53.957 30.22 -19.49 -22.0095
IC1151 239.6347 17.4415 24.21 -19.38 -21.508
ESO234-049 308.8254 -49.8655 31.19 -19.33 -21.8731
UGC11093 270.4656 6.9683 21.18 -19.23 -22.2496
UGC10862 262.0374 7.4226 25.35 -19.22 -20.3179
ESO286-063 317.4682 -45.5276 31.81 -19.21 -21.9048
ESO186-062 308.5086 -52.9812 31.19 -19.1 -22.2241
IC4986 304.2982 -55.0364 23.75 -19.08 -19.9153
UGC11030 268.6407 2.8794 27.67 -19.06 -19.63
ESO340-032 306.7336 -39.6159 33.54 -18.98 -21.1668
IC4821 287.3833 -55.0173 25.0 -18.98 -21.6087
IC4817 286.5516 -56.1594 33.42 -18.96 -21.27
NGC6861D 302.0812 -48.2114 33.42 -18.9 -23.421
NGC6707 283.8415 -53.8186 33.42 -18.9 -22.969
ESO340-010 304.3582 -41.1334 39.26 -18.82 -22.1218
IC4871 293.9259 -57.5191 22.59 -18.8 -20.8786
ESO285-048 311.1676 -45.9786 28.18 -18.77 -21.3327
ESO185-027 299.0568 -56.9106 23.81 -18.73 -21.9358
NGC6902B 305.7795 -43.8686 34.67 -18.69 -20.7538
ESO236-006 320.2867 -47.5151 28.93 -18.66 -19.5207
NGC6149 246.8508 19.5972 30.57 -18.65 -22.1455
NGC6990 314.9871 -55.562 25.36 -18.57 -21.0847
ESO233-035 302.3566 -48.2848 33.97 -18.57 -22.2335
NGC7090 324.1204 -54.5576 6.28 -18.56 -20.8258
NGC6861E 302.7564 -48.6908 33.9 -18.55 -21.044
ESO235-085 319.5675 -48.5375 24.03 -18.53 -21.6278
NGC7022 317.3967 -49.3037 29.49 -18.51 -22.1184
ESO235-001 312.2578 -47.2987 33.75 -18.51 -20.2164
PGC061359 271.0942 7.2804 28.11 -18.5 -23.0103
IC4885 295.9668 -60.6517 29.92 -18.39 -21.3538
IC4888 296.2176 -54.4567 29.82 -18.29 -21.2615