LIGO/Virgo G275697

The LIGO Scientific Collaboration and Virgo report:

The pycbc CBC analysis (Usman et al. 2016, CQG 33, 215004) identified
candidate G275697 during real-time processing of data from LIGO
Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at
2017-02-27 18:57:31.375 UTC (GPS time: 1172257069.375).

G275697 is an event of interest because its false alarm rate, as
determined by the online analysis, is 1.43e-07 Hz or about one in 2
months, passing our alert threshold of ~1/month. The event's
properties can be found at this URL:

https://gracedb.ligo.org/events/G275697

No other GW event candidates were identified within a 300 s window
before or after G275697.

Based on preliminary matched-filter estimates of the masses and spins,
if astrophysical, there is a 100% chance that the less massive companion
in the binary has a mass less than 3 Msun. Based on the tidal disruption
condition and disk mass formula of Foucart (PRD 86, 124007), using an
implementation based on Pannarale & Ohme (ApJL 791, 7), we estimate
that there is a 100% chance that the system ejected enough neutron-rich
material to power an electromagnetic transient.

One sky map with directional distance information (e.g., Singer et al.
2016, ApJL 829, 15) is available at this time and can be retrieved from
the GraceDB event page: bayestar.fits.gz, an initial localization generated
by the BAYESTAR pipeline. The probability is concentrated in two
sections of an annulus. The 50% credible region spans about 480 deg2 and
the 90% region about 1800 deg2. The luminosity distance is estimated to
be 181 +/- 55 Mpc (mean +/- standard deviation). This is the preferred sky
map at this time.

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 G275697.  We compared the candidate source directions of 3 temporally-coincident neutrinos to the BAYESTAR skymap, with the following parameters:

#  dt[s]   RA[deg] Dec[deg] E[TeV] Sigma[deg]
--------------------------------------------
1. -428.91 166.1   39.1     0.51   1.9
2. -340.37 287.4   43.4     0.43   1.5

(dt--time from GW; RA/Dec--sky location; E--reconstructed secondary muon energy; Sigma--uncertainty of direction reconstruction)

The analysis found NO COINCIDENT ONLINE TRACK-LIKE NEUTRINO CANDIDATES detected by IceCube within the 500 second window surrounding G275697 within the BAYESTAR skymap.

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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 >.

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 G275697 event using the initial LIGO bayestar probability map at event time (LVC GCN Circ. 20763
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 ). 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/G275697.png (gwantares/ANT@GW). Considering the location probability provided by the LIGO collaboration, there is a 48% 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 G275697 event time. The expected number of atmospheric background events in the region visible by ANTARES is ~2.0e-3 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.

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 G275697.  The satellite was
pointing at RA=15:29:10 Dec=-55:09:03 (in the direction of the
Norma Region), close to the low-probability area of LIGO
localization. About 6.5% of the probability was contained in the field
of view of INTEGRAL IBIS and SPI. Depending on the location within the
LIGO 90% localization region, as well as the assumed counterpart
spectrum and duration, the best upper limit is set by the
anti-coincidence shield of the spectrometer on board of INTEGRAL
(SPI/ACS), the anti-coincidence shield of the IBIS instrument
(IBIS/Veto), or by the imaging coded mask instruments (IBIS and SPI).
The combination of these instruments covered the full LIGO 90%
confidence region and provided stringent constraints on the flux of a
possible electromagnetic counterpart in the energy range covered by
the INTEGRAL instruments.

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 (2017-02-27 18:57:31.375
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 4.3e-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 slope 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 slope of -0.5
and an Epeak = 500 keV: we estimate that 20% of the LIGO localization
probability region is covered with a range of sensitivity from optimal
for SPI-ACS (mentioned above) to 50% worse. About 2% of the LIGO
localization in the field of view of IBIS and SPI is covered with at
least factor 2 better sensitivity.

The SPI/ACS light curves, binned at 50 ms, are derived from 91
independent detectors with different lower energy thresholds (mainly
between 50 keV and 150 keV) and an upper threshold at about 100
MeV. The ACS response varies substantially as a function of the source
incident angle with an optimal effective area of about 6000 cm2 at 1
MeV.

A. Ursi (INAF/IAPS), P. Munar-Adrover (INAF/IAPS), F. Verrecchia (ASDC and
INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Bulgarelli,
V. Fioretti, A. Zoli, N. Parmiggiani (INAF/IASF-Bo), C. Pittori, F. Lucarelli
(ASDC and INAF/OAR), G. Minervini, M. Cardillo, G. Piano, A. Argan, Y.
Evangelista (INAF/IAPS), I. Donnarumma (ASI), F. Fuschino, M. Marisaldi
(INAF/IASF-Bo and Bergen University),  A. Giuliani (INAF/IASF-Mi), M. Pilia,
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 G275697 at T0 = 2017-02-27
18:57:31.375 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 sec from the LIGO T0.

Two data acquisitions where collected about 30 sec before and 45 sec after
the LIGO T0; they show no significant transient candidate event. About 80%
of the LIGO error box was observable by the AGILE MCAL. A 3-sigma UL was
computed for a 1 s integration time, on different celestial positions within
the G275697 error box and varies from a minimum of 4.7e-7 erg cm^-2 to a
maximum of 11.3 e-7 erg cm^-2, assuming as spectral model a simple power law
with photon index 1.4. The AGILE-MCAL instrument 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.

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

In response to the LIGO/Virgo GW trigger G275697 we performed an analysis
of the AGILE Gamma-Ray Imaging Detector (GRID) data on different timescales.
On LIGO trigger time (T0= 2017-02-27 18:57:31.375 UT) the GRID exposure
covered about 50% of the LIGO localization region that was observed with
off-axis angles between 40 and 70 deg, approximately.
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 minimal
3-sigma upper limits obtained within the accessible G275697 localization
region are reported below:

9.8e-07 erg cm^-2 s^-1 for integration time of 2s,
1.7e-07 erg cm^-2 s^-1 for integration time of 20s,
3.9e-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.

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), N. Gehrels (NASA/GSFC),
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 $B!^(B 100 s of the
LIGO event G275697 (LIGO/VIRGO Collaboration GCN Circ. 20763
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 ),
where T0 is the LIGO trigger time (2017-02-27T18:57:31.375 UTC).

The BAT pointing position at T0 is

RA = 284.163 deg,
DEC = -37.915 deg,
ROLL = 78.846 deg.

The BAT Field of View (>10% partial coding) covers 8.28% of the integrated
LIGO localization probability.

No significant detections (signal-to-noise ratio > 4 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 ~ 6.8 x 10^-8 erg/s/cm^2.
Moreover, so far no event data are found within T0 $B!^(B 100 s.

BAT retains decreased, but significant, sensitivity to rate increases for
gamma-ray events outside of its FOV. About 58.37% 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.

P.A. Evans (U. Leicester), J.A. Kennea (PSU), S.D. Barthelmy
(NASA/GSFC), A.P. Beardmore (U. Leicester), A.A. Breeveld (UCL-MSSL),
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. Giommi (ASI), C. Gronwall (PSU), H.A. Krimm
(CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), D.
Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),
B. Mingo (U. Leicester),  J.A. Nousek (PSU), S.R. Oates (U. Warwick),
P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U.
Leicester), K.L. Page (U.Leicester), D.M. Palmer (LANL), 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:

Swift has performed a series of 62 observations of galaxies (from the
2MPZ catalogue) within the LVC error region for the GW trigger G275697,
using the 'bayestar' GW localisation map. As this is a 3D skymap,
galaxy distances were taken into account in selecting which ones to
observe. The observations currently span from 15 ks to 24 ks after the
LVC trigger, and cover 7.6 sq degrees on the sky (corrected for
overlaps). This covers 0.011 of the probability in the LVC skymap, and
0.022 of the probability in the LVC map after convolving with the 2MPZ
galaxy catalogue, as described by Evans et al., (2016, MNRAS,  462,
1591).

We have detected a 1 X-ray source. Each source is assigned a rank of
1-4 which describes how likely it is to be related to the GW trigger,
with 1 being the most likely and 4 being the least likely. The ranks
are described at http://www.swift.ac.uk/ranks.php.

The detected source is currently given "rank 3" since it is only
1.6-sigma above the historical upper limit at this location from the
Rosat All Sky Survey, and therefore cannot be identified as a new
source with a significant degree of confidence. We only have a single
data point so cannot comment on variability. We note, however, that
this uncatalogued source is consistent with a galaxy in 2MPZ with a
distance (based on a photometric redshift) of at 291 �� 61 Mpc. The
LIGO distance probability on the line of sight to this has mean 160 and
sigma 57 Mpc. 96% of the integral of the LIGO distance function (Singer
et al., 2016, ApJL, 829, 15) along this line of sight lies within the
3-sigma confidence interval on this galaxy's position. Follow up
observations of this source are encouraged. 

We have found:

  * 0 sources of rank 1
  * 0 sources of rank 2
  * 1 source of rank 3
  * 0 sources of rank 4

For all flux conversions and comparisons with catalogues and upper
limits from other missions, we assumed a power-law spectrum with
NH=3e20 cm^2, and photon index (Gamma)=1.7


RANK 3 sources
==============

These are uncatalogued X-ray sources, however they are not brighter
than previous upper limits, so do not stand out as likely counterparts
to the GW trigger.
  
  Source 1:
  =============
    RA: 	 324.9781 ( = 21h 39m 54.74s) J2000
    Dec:	 +44.7641 ( = +44d 45' 50.8") J2000
    Error:	 +5.9 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.1e-01 +/- 5.0e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 4.7e-12 +/- 2.1e-12 erg cm^-2 s^-1 (0.3-10 keV)
    1XMM UL:	 7.4e-12 ct/sec, (0.3-10 keV)
		 So the source is 1.3-sigma above the 
		 XMM 3-sigma upper limit.
    RASS UL:	 3.0e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)

		 So the source is not above the RASS 3-sigma upper 
		 limit.
    There is no evidence for fading.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source,
    and consistent (within 3-sigma) with the distance to the GW object.

    There is 1 2MASS object within the source's 3-sigma error radius.

This circular is an official product of the Swift team.

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 G275697 (2017-02-27 18:57:31.375 UTC, hereafter T0; LIGO/VIRGO 
Collaboration GCN Circ. 20763
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 ).

No triggered KW event happened from ~5 days before to more than 10 hours
after T0. We found no significant (> 5 sigma) detection on temporal 
scales from 2.944 s to 100 s using waiting mode data from both KW 
detectors S1 and S2 within the interval T0 +/- 100 s.

We estimate an upper limit (90% conf.) on the 10 keV ��� 10 MeV fluence to
7.8x10^-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 2.7x10^-7 erg/cm^2/s (10 keV - 10 MeV, 2.944 s scale).

All the quoted values are preliminary.

A. Melandri, P. D'Avanzo (INAF-OAB), G. Greco (Urbino University/INFN Firenze), D. Fugazza, S. Covino, (INAF-OAB), E. Palazzi (INAF-IASF Bo), M. Branchesi (Urbino University/INFN Firenze), L. Amati (INAF-IASF Bo), L. A. Antonelli, (INAF-OAR), S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC),  S. Campana (INAF-OAB), E. Cappellaro (INAF-OAPD), V. D'Elia (INAF-ASDC), F. Getman (INAF-OAC), A. Grado (INAF-OAC), L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), L. Nicastro (INAF-IASF Bo), E. Pian (SNS-Pisa), S. Piranomonte (INAF-OAR), L. Pulone (INAF-OAR), A. Rossi (INAF-IASF Bo), G. Stratta (Urbino University/INFN Firenze), G. Tagliaferri (INAF-OAB), V. Testa (INAF-OAR), L . Tomasella (INAF-OAPD), S. Yang (INAF-OAPD), E. Brocato (INAF-OAR) on behalf of GRavitational Wave Inaf TeAm (GRAWITA) report:

We carried out optical/NIR follow-up observations of the LIGO/Virgo GW trigger G275697 (LVC GCN Circ. 20763
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 ) with the 60-cm robotic telescope REM located at the La Silla Observatory (Chile). The observations were carried out on 2017 Feb 28 from 00:12:54 UT to 04:59:04 UT (from 5.25 to 10.04 hours after T0, LVC GCN Circ. 20763
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 ), simultaneously in the g, r, i, z and H bands. 

We observed the twenty brightest (according to the B magnitude reported in the GLADE catalogue) galaxies within the bayestar probability sky map visible from La Silla. The galaxies with a catalogued distance in the range 80-280 Mpc (evaluated on the basis of directional distance information, Singer et al. 2016, ApJL 829, 15) and brighter than absolute B_Mag ~ -21.3 were selected within the 30% containment  probability contour of the sky map using the GWsky script (https://github.com/ggreco77/GWsky).


RA(J2000)  Dec(J2000) Dist(Mpc) Mag(B)
-------------------------------------------------------
174.160   -38.3830    275.633  -22.09
163.889   -28.5261    112.893  -22.04
171.471   -35.3945    136.773  -21.97
171.850   -35.0727    153.462  -21.90
164.899   -29.5633    86.5000  -21.87
164.007   -28.3702    257.040  -21.84
171.087   -35.0165    240.991  -21.65
164.058   -28.9641    277.971  -21.64
175.374   -38.4629    246.604  -21.56
168.117   -32.1972    243.220  -21.49
170.986   -34.8010    242.103  -21.47
175.459   -37.9629    259.418  -21.46
172.862   -37.4394    269.153  -21.43
174.692   -37.7118    133.660  -21.41
168.150   -33.3339    140.605  -21.40
160.274   -24.4960    230.144  -21.40
165.627   -29.8585    248.886  -21.34
164.473   -28.3671    215.774  -21.31
171.862   -34.9971    276.694  -21.30
173.608   -36.8816    236.592  -21.29


A preliminary analysis reveals no obvious optical/NIR candidate counterpart in the above galaxies down to the following magnitudes: r > 19.3, H > 16.5 (AB, 3sigma upper limit, calibrated against the APASS and 2MASS catalogues, respectively).
 
Further analysis is in progress.

G. Vianello (Stanford), N.Omodei (Stanford), Daniel Kocevski (NASA/MSFC)
and Sara Buson (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 G275697.

Fermi-LAT had an instantaneous coverage of ~20% at the time of the trigger
(T0 =  2017-02-27 18:57:31.375 UTC), and reached 100% cumulative coverage
within ~7 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 100 GeV for this search vary
between  3e-10 ��� 3e-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.

B. Li, H.B. Zhao (PMO/CAS), D. Xu (NAO/CAS), G.T. Zhaori, H. Lu, R.Q. 
Hong, L.F. Hu (PMO/CAS), T.M. Zhang, X. Zhou, H.X. Feng, Z.P. Zhu 
(NAO/CAS), J.Z. Liu, H.B. Niu, Y. Zhang, X. Zhang, G.X. Pu, S.G. Ma,T.Z. 
Yang, F.F. Song (XAO/CAS), J. Mao, J.M. Bai (YNAO/CAS) report on behalf 
of the GWFUNC collaboration:

We have performed tiled observations of LIGO/Virgo G275697 (LVC, GCN 
20763
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 ) using the 1-m Chinese Near Earth Object Survey Telescope (CNEOST) 
at Xuyi, Jiangsu, China.

CNEOST carried out observations during 11:29:44.6 UT - 14:51:15.1 UT on 
2017-02-28 in the Sloan r-filter. The imaging coverage on top of the GW 
probability map is at

https://dl.dropboxusercontent.com/u/3665676/G275697/skymapG275697CNEOST.pdf

and the limiting magnitude varied from m(r)~16 to ~20 mag due to weather 
variation.

Preliminary analysis doesn't reveal credible optical transients except 
supernovae discovered prior to the G275697 trigger time.

V.M.  Lipunov, E. Gorbovskoy, N.Tyurina, V.Shumkov,
  P.Balanutsa, V.G. O.Gress, Kornilov, 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 Global robotic Net observed G275697 error-box synchronousely by 
very wide field cameras (MASTER-VWFC 2x400 square degrees) with 
m_lim=11mag on the single 
images,
covering north (MASTER-Tunka) and south (MASTER-SAAO) parts of error-box.

MASTER-II   G275697 inspection started 29min05s after the trigger time, 
covering 338 degrees for 24h after the trigger time up to 20.5mag, 640 for 
36h after trigger time.

http://master.sai.msu.ru/static//ligo/db/G275697/151//img/ligo_master_2017-02-28-19-11-23.12.eb.png
http://master.sai.msu.ru/static//ligo/db/G275697/151//img/ligo_master_2017-02-28-19-11-23.eb.png


MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
started inspection of the the  LIGO/Virgo G275697
29min05s after the trigger time (18:57:31.375 Siellez et al GCN#20763
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 )  on 
2017-02-27 19:26:36 UT.

The 5-sigma upper limit on the single images are 20.0-20.3, the summ are 
20.8 mag

MASTER-IAC  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
started inspection of the the  LIGO/Virgo G275697
after sunset 49min28s after the trigger time on2017-02-27 19:46:59


The 5-sigma upper limit on the single images are 20.0-20.3, the summ are 
20.8 mag


MASTER optical transients, detected during G275697 error-box inspection:

1) MASTER OT J225444.27+755459.8 discovery - not connected with trigger!

MASTER-IAC auto-detection system  ( Lipunov et al., "MASTER Global Robotic 
Net", Advances in Astronomy, 2010, 30L )  discovered OT source at (RA, 
Dec) = 22h 54m 44.27s +75d 54m 59.8s on 2017-02-26.93361 UT
with unfiltered m_OT= 16.9m (mlimit=19.1m).

The OT is seen in 8 images. We have reference image without OT on 
2015-08-18.99625 UT with unfiltered magnitude limit 19.6m.

There is no any sources in VIZIER inside 3", it means 22mag POSS limit in 
history and Amplitude of curent outburst more then 5.1mag (as minimum)

Spectral observations are required.

The discovery and reference images are available at:

http://master.sai.msu.ru/static/OT/225444.27755459.8.png


2)  MASTER OT J104304.78+020550.2 detection - QSO activity

MASTER-SAAO auto-detection system  discovered OT source at (RA, Dec) = 10h 
43m 04.78s +02d 05m 50.2s on 2017-02-27.80508 UT.

The OT unfiltered magnitude is 18.5m  (mlim=20.0).

The OT is seen in 4 images. We have reference image on 2015-04-22.74625 UT 
with  unfiltered mlim=19.7m and m_QSO<~19.7.

Y. Yamada, A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama (AGU),
K. Yamaoka (Nagoya U), S. Nakahira (JAXA), I. Takahashi (IPMU), Y. Asaoka,
S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR),
M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The CALET Gamma-ray Burst Monitor (CGBM) was operating at the trigger time
of G275697 (GCN Circ. 20763
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 ).  No CGBM on-board trigger occurred at the time
of the event.  Based on the LIGO localization sky map (bayestar.fits.gz),
the part of the northern arc of the high probability area was in the field-of-view of
CGBM.  The summed LIGO probabilities inside the HXM and the SGM field of view
are 32% and 70%.

Based on the analysis of the light curve data with 0.125 sec time resolution
from -60 sec to 60 sec from the trigger time, we found no significant excess
around the trigger time in either the HXM (7-3000 keV) or the SGM (40 keV -28 MeV)
data.

The CALET Calorimeter (CAL) was operating in high energy trigger mode at the
trigger time of G275697.  However, no LIGO high probability region was included
in the CAL's field of view at the time of the trigger.

M. M. Kasliwal (Caltech), S. M. Adams (Caltech), C. Cannella (Caltech), R.
Lunnan (Caltech), R. Ferretti (OKC), T. Kupfer (Caltech), L. P. Singer
(NASA/GSFC), S. B. Cenko (NASA/GSFC), R. Walters (Caltech), T. Barlow
(Caltech), J. Rana (IUCAA), V. Bhalerao (IIT-B), A. A. Miller
(Northwestern/Adler), Y. Cao (UW), R. Laher (IPAC), F. Masci (IPAC)

report on behalf of the iPTF (intermediate Palomar Transient Factory) and
GROWTH (Global Relay of Observatories Watching Transients Happen)
collaborations:

We performed tiled observations of LIGO/Virgo G275404 (LVC, GCN 20738
Loading...
 
 ) and
LIGO/Virgo G275697 (LVC, GCN 20763
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 ) using the Palomar 48-inch Oschin
telescope (P48) on the night of 2017-03-01 UTC (delay due to inclement
weather). We imaged 84 fields spanning 633 square degrees, with a 13%
chance of containing the true location of G275404. Of these, 47 fields (361
square degrees) were imaged twice, containing 6% probability of containing
G275404, and searched for transient candidates.

During preliminary sifting through candidate variable sources using image
subtraction by our IPAC (Masci et al. 2016) and NERSC (Cao et al. 2016)
pipelines, a total of 140 candidates were saved in the fields imaged.
Applying standard iPTF vetting procedures and removing transients with a
history of previous variability, we flagged 2 optical transient candidates
in the 90% contour of G275697, listed below, for further follow-up.

Name        RA (J2000)      Dec (J2000)     UTC          R-mag
Notes
iPTF17bou   148.739102      -7.943791       09:07        18.72
fading (0.3 mag intranight); nuclear/stellar?
iPTF17bpw   147.851104      -9.136385       09:03        19.16
pstar=0.013; nuclear

Positions are stated in the ICRS. Discovery times are noted in UTC hh:mm on
2017-03-01. Magnitudes are based on image subtraction and are in the Mould
R filter, calibrated with respect to point sources in SDSS as described in
Ofek et al. 2012.

We caution that many candidates are outside the SDSS footprint and lack a
secure star/galaxy classification for the underlying source. We flag these
as "nuclear/stellar?". Where available, we provide machine-learning
probability scores on whether the underlying source is a galaxy/star (0/1)
(Miller et al. 2016).

We are grateful to the Palomar crew (especially John Henning, Jeff
Zolkower, Carolyn Heffner, Jamey Eriksen, Nick Ganciu) for their hard work
in reviving a faulty declination encoder essential to collecting this
dataset during the last two days of iPTF survey operations.

J.Y. Wei (NAOC), C. WU (NAOC), J. Wang (NAOC), N. Leroy (LAL),
S. Antier (LAL), X.H. Han (NAOC), L.P. Xin (NAOC), X.M. Meng (NAOC),
L. Huang (NAOC), Y. Xu (NAOC), H.B. Cai (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),
J.L. Atteia (IRAP), D. Götz (CEA), C.Lachaud (APC),
on behalf of the SVOM Gravitational Astronomy group report:

We observed about 2000 square degree (5 sky regions) of the skymap
of the advanced LIGO trigger G275697, 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 7.44% prior
probability that these 5 regions contain the true location of the
source.

The coordinates of the 5 regions and observation time are list following:

start-obs(UTC)  end-obs(UTC)    Ra      Dec     Camera_ID
2017-03-01      10:55:43.4      2017-03-01      18:11:04.6      09:10:04.5
     +29:30:47                       C1
2017-03-01      10:55:26.9      2017-03-01      14:04:55.7      03:52:34.0
     +68:53:23                       C3
2017-03-01      10:55:26.9      2017-03-01      14:04:55.7      04:02:12.2
     +48:48:08                       C4
2017-03-01      10:55:24.5      2017-03-01      17:44:07.8      06:34:55.5
     +69:32:01                       C5
2017-03-01      10:55:24.5      2017-03-01      17:44:07.8      06:40:15.5
     +50:32:35                       C6

The first image was taken ~2 days 16 hours after the event trigger
due to bad wheather condition. No any significant transient is
found in our online pipeline. The image analysis is ongoing in
detailed processing with our offline pipeline.

Johan P.U. Fynbo, Daniele Malesani, Lise Christensen (DARK/NBI), Giorgos 
Leloudas (WIS), and Elena Pian (SNS; INAF/IASF Bo) report on behalf of a 
larger collaboration:

We observed the location of the X-ray "source 1" within the LVC error 
region for the GW trigger G275697 (LVC Circ. 20763) reported by Swift 
(Evans et al., LVC Circ. 20773) using the Nordic Optical Telescope (NOT) 
equipped with the ALFOSC camera and spectrograph. Observations were 
carried out in the r band, and started on 2017 Mar 1.25 UT (in twilight, 
at high airmass).

We clearly detect the 2MPZ galaxy mentioned by Evans et al. (LVC GCN 
20773
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 ) and coincident with the X-ray source. We measure a magnitude r = 
16.67 +- 0.01 AB (5" aperture radius, calibrated against nearby stars 
from the Pan-STARRS catalog). This value is consistent with the (Kron) 
magnitude r = 16.68 listed in the Pan-STARRS catalog, indicating no 
variability compared with the archival value.

A 900-s spectrum was obtained covering the wavelength range 3300-9500 
AA, under non-photometric conditions. Several emission lines are 
detected, corresponding to Halpha, Hbeta, the [O III] doublet, [N II] 
and [S II], all at a common redshift z = 0.0385, corresponding to a 
(luminosity) distance of 170 Mpc.

The width of the Halpha and Hbeta lines is around 1700 km s^-1, 
indicating the presence of a broad-line region typical of an AGN. Also, 
the location of this object in the extinction-insensitive BPT diagram 
(e.g. Kewley et al. 2013, ApJ, 774, L10) is consistent with LINERs and 
AGN. We caution that the [N II] lines, used for the BPT diagram, falls 
at this redshift close to the telluric B band, but correcting for the 
flux loss should, if anything, move our target even more towards the AGN 
locus. Finally, we note that the Halpha/Hbeta ratio indicates 
significant extinction, even after correcting for the non-negligible 
Galactic reddening (A_V ~ 1 mag).

Our data thus indicate that the XRT source 1 is an AGN, which would 
naturally explain the detected X-ray emission (at a level of ~10^43 erg 
s^-1).

We acknowledge excellent support from the NOT staff, in particular Pere 
Blay and Amanda Djupvik.

Sujay Mate (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 G275404 trigger time, UT 2017-02-25 18:30:21.374, 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 baystar skymap provided by LVC (baystar.fits.gz), the sky visible to CZTI has 27.8% probability of containing the EM counterpart.

CZTI data were de-trended to remove orbit-wise background variation. We then searched data from three of the four independent, identical quadrants to look for coincident spikes in the count rates. For this particular event, data from one quadrant (quadrant C) was rejected due to noisy pixels. 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 12 neighbouring orbits. We selected confidence levels such that the probability of a false trigger in this 100s window is 10^-3. 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 band, the upper limits for source fluence are 4.22e-07 ergs/cm^2, 1.03e-06 ergs/cm^2 and 2.31e-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 4.2e-06, 1.03e-06, and 2.31e-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/G275697/files/G275697_CZTI_limits.pdf,0

Adam Goldstein (USRA) and Colleen Wilson-Hodge (NASA/MSFC) report on behalf
of the GBM-LIGO Group:
Lindy Blackburn (CfA), Michael S. Briggs (UAH), Jacob Broida (Carleton
College), Eric Burns (UAH), Jordan Camp (NASA/GSFC), Tito Dal Canton
(NASA/GSFC), Nelson Christensen (Carleton College), Valerie Connaughton
(USRA), Rachel Hamburg (UAH), C. Michelle Hui (NASA/MSFC), Pete Jenke
(UAH), Dan Kocevski (NASA/MSFC), Nicolas Leroy (LAL), Tyson Littenberg
(NASA/MSFC), Julie McEnery (NASA/GSFC), Rob Preece (UAH), Judith Racusin
(NASA/GSFC), Peter Shawhan (UMD), Karelle Siellez (GA Tech), Leo Singer
(NASA/GSFC), John Veitch (Birmingham), Peter Veres (UAH)

Fermi GBM observed 69% of the bayestar sky map at the time of the LIGO
trigger, and we set the following flux upper limits for the entire visible
sky map (excluded region is a circle with radius of 68 degrees centered on
RA, Dec = 326.9, -22.8).

Using a hard Band function with (Epeak, alpha, beta) = (500 keV, -0.5,
-2.5), we set a 3 sigma, 1-second-averaged flux upper limit for any
transient within 30 s of the LIGO trigger time in the 10-1000 keV band
ranging from 4.6e-7 to 6.0e-7 erg/s-cm^2.  Using an exponentially cutoff
power law parametrized with (Epeak, index) = (566 keV, -0.42), which
represents the average GBM-triggered short GRB, the upper limit ranges from
5.0e-7 to 6.4e-7 erg/s-cm^2.

Using the Earth Occultation technique (Wilson-Hodge et al. 2012, ApJS, 201,
33) to estimate the amount of persistent emission during a 48-hour period
centered on the LIGO trigger time, we place the following range of 3-sigma
day-averaged flux upper limits based on observed sources over the entire
LIGO sky map:

Energy       min  max  median
--------------------------------
 12- 27 keV: 0.08 0.45 0.12 Crab
 27- 50 keV: 0.14 0.66 0.20 Crab
 50-100 keV: 0.17 0.80 0.24 Crab
100-300 keV: 0.34 1.67 0.49 Crab
300-500 keV: 1.85 10.2 2.55 Crab

These limits are based on the minimum requirement that each source in the
Earth Occultation catalog was Earth-occulted at least 6 times in each of
the 24 hour periods preceding and following the LIGO trigger and that the
occultations were well separated from nearby bright sources.

P.A. Evans (U. Leicester), J.A. Kennea (PSU), S.D. Barthelmy
(NASA/GSFC), A.P. Beardmore (U. Leicester), A.A. Breeveld (UCL-MSSL),
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. Giommi (ASI), C. Gronwall (PSU), H.A. Krimm
(CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), D.
Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),
B. Mingo (U. Leicester),  J.A. Nousek (PSU), S.R. Oates (U. Warwick),
P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U.
Leicester), K.L. Page (U.Leicester), D.M. Palmer (LANL), 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:

Swift has performed a series of 1330 observations of galaxies (from the
2MPZ catalogue) within the LVC error region for the GW trigger G275697,
using the 'bayestar' GW localisation map. As this is a 3D skymap,
galaxy distances were taken into account in selecting which ones to
observe. The observations currently span from 15 ks to 184 ks after the
LVC trigger, and cover 160 sq degrees on the sky (corrected for
overlaps). This covers 0.15 of the probability in the LVC skymap, and
0.29 of the probability in the LVC map after convolving with the 2MPZ
galaxy catalogue, as described by Evans et al., (2016, MNRAS,  462,
1591).

Since the last Swift GCN, we have detected 6 X-ray sources, these are
either new detections, or have been given a higher 'rank' than in the
last circular. Each source is assigned a rank of 1-4 which describes
how likely it is to be related to the GW trigger, with 1 being the most
likely and 4 being the least likely. The ranks are described at
http://www.swift.ac.uk/ranks.php.

We have found:

  * 0 sources of rank 1
  * 0 sources of rank 2
  * 1 source of rank 3
  * 5 sources of rank 4

For all flux conversions and comparisons with catalogues and upper
limits from other missions, we assumed a power-law spectrum with
NH=3e20 cm^2, and photon index (Gamma)=1.7


RANK 3 sources
==============

These are uncatalogued X-ray sources, however they are not brighter
than previous upper limits, so do not stand out as likely counterparts
to the GW trigger.
  
  Source 8:
  =============
    RA: 	 17.4334 ( = 01h 09m 44.02s) J2000
    Dec:	 +73.1996 ( = +73d 11' 58.6") J2000
    Error:	 +5.6 (arcsec, radius, 90% confidence).
    Peak Rate:	 0.0e+00 +/- 0.0e+00 ct/sec (0.3-10 keV)
    Peak Flux:	 0.0e+00 +/- 0.0e+00 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 0.0e+00 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)
       so the source is not above the RASS 3-sigma upper limit.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.


RANK 4 sources
==============

These are catalogued X-ray sources, showing no signs of outburst
compared to previous observations, so they are not likely to be related
to the GW trigger.
  
  Source 2:
  =============
    RA: 	 153.9839 ( = 10h 15m 56.14s) J2000
    Dec:	 -20.0412 ( = -20d 02' 28.3") J2000
    Error:	 +5.6 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.7e-01 +/- 6.0e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 7.1e-12 +/- 2.6e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J101556.7-200219 in the ROSAT/RASSBSC catalogue
    Separation:  12.3" from the XRT source
    Cat Rate:	 1.6e-01 +/- 2.3e-02 ct/sec 
    Cat Flux:	 4.4e-12 +/- 6.3e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 1.0-sigma above the catalogued flux.
    There is no evidence for fading.
    There are 2 GWGC or 2MPZ galaxies within 200 kpc of the source.
      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `2MASX J10155660-2002268' is 6.9" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 3:
  =============
    RA: 	 174.7569 ( = 11h 39m 1.66s) J2000
    Dec:	 -37.7381 ( = -37d 44' 17.2") J2000
    Error:	 +4.2 (arcsec, radius, 90% confidence).
    Peak Rate:	 9.8e-01 +/- 1.9e-01 ct/sec (0.3-10 keV)
    Peak Flux:	 4.2e-11 +/- 8.3e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1SXPS J113901.5-374416 in the 1SXPS catalogue
    Separation:  1.0" from the XRT source
    Cat Rate:	 1.9e+00 +/- 1.5e-02 ct/sec 
    Cat Flux:	 8.3e-11 +/- 6.4e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    The source may be fading, at the 1.1-sigma level.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `NGC  3783' is 1.6" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 4:
  =============
    RA: 	 174.0675 ( = 11h 36m 16.20s) J2000
    Dec:	 -38.0356 ( = -38d 02' 08.2") J2000
    Error:	 +6.8 (arcsec, radius, 90% confidence).
    Peak Rate:	 9.1e-02 +/- 3.5e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 3.9e-12 +/- 1.5e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J113616.1-380210 in the ROSAT/RASSBSC catalogue
    Separation:  2.6" from the XRT source
    Cat Rate:	 2.1e-01 +/- 2.7e-02 ct/sec 
    Cat Flux:	 5.9e-12 +/- 7.5e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    There is no evidence for fading.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `V* V858 Cen' is 3.2" away.
    There are 2 2MASS objects within the source's 3-sigma error radius.
  
  Source 5:
  =============
    RA: 	 218.9470 ( = 14h 35m 47.28s) J2000
    Dec:	 -52.6808 ( = -52d 40' 50.9") J2000
    Error:	 +5.9 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.9e-01 +/- 6.7e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 8.0e-12 +/- 2.9e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  XMMSL1 J143548.8-524058 in the XMM-NEWTON/XMMSLEWCLN
catalogue
    Separation:  6.9" from the XRT source
    Cat Rate:	 1.7e+00 +/- 5.0e-01 ct/sec 
    Cat Flux:	 1.7e-11 +/- 5.0e-12 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    There is no evidence for fading.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `CD-52  6194' is 8.1" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 6:
  =============
    RA: 	 325.6803 ( = 21h 42m 43.27s) J2000
    Dec:	 +43.5868 ( = +43d 35' 12.5") J2000
    Error:	 +4.2 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.7e+00 +/- 4.2e-01 ct/sec (0.3-10 keV)
    Peak Flux:	 1.2e-10 +/- 1.8e-11 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1SXPS J214242.7+433509 in the 1SXPS catalogue
    Separation:  5.9" from the XRT source
    Cat Rate:	 1.8e+00 +/- 1.8e-02 ct/sec 
    Cat Flux:	 7.7e-11 +/- 7.7e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 2.2-sigma above the catalogued flux.
    There is no evidence for fading.
    There are 10 GWGC or 2MPZ galaxies within 200 kpc of the source.
      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `V* SS Cyg' is 5.8" away.
    There is 1 2MASS object within the source's 3-sigma error radius.

This circular is an official product of the Swift team.

S. M. Adams (Caltech), C. Cannella (Caltech), A. A. Miller
(Northwestern/Adler), S. Papadogiannakis (OKC), R. Lunnan (Caltech), N.
Blagorodnova (Caltech), L. P. Singer (NASA/GSFC), S. B. Cenko (NASA/GSFC),
R. Walters (Caltech), T. Barlow (Caltech), J. Rana (IUCAA), V. Bhalerao
(IIT-B),  Y. Cao (UW), R. Laher (IPAC), F. Masci (IPAC) and M.M. Kasliwal
(Caltech)

report on behalf of the iPTF (intermediate Palomar Transient Factory) and
GROWTH (Global Relay of Observatories Watching Transients Happen)
collaborations:

We have continued tiled observations of LIGO/Virgo G275404 (LVC, GCN
20738
Loading...
 
 ) and LIGO/Virgo G275697 (LVC, GCN 20763
Loading...
 
 ) using the Palomar 48-inch
Oschin telescope (P48). Including our first night of observations on
2017-03-01 UTC (GCN 20791
Loading...
 
 ) and a second night on 2017-03-02, we have
observed a total of 240 fields spanning 1747 square degrees. We estimate a
20% chance that these fields contain the true location of G275404 and a
25% chance that they containing the true location of G275697.

During preliminary sifting through candidate variable sources using image
subtraction by our IPAC (Masci et al. 2016) and NERSC (Cao et al. 2016)
pipelines, a total of 115 candidates were saved in the fields imaged.
Applying standard iPTF vetting procedures and removing transients with a
history of previous variability, we flagged 16 optical transient candidates
in the 90% localization contour of G275697, listed below, for further
follow-up.

We encourage spectroscopic classification of these candidates. In
particular, we highlight 17bub and 17buo as fast-evolving by more than 0.3
mag in the same night.

We are grateful to the Palomar crew (John Henning, Jeff Zolkower, Carolyn
Heffner, Jamey Eriksen, Nick Ganciu) for their hard work in reviving a
faulty declination encoder essential to collecting this dataset during the
last two days of iPTF survey operations.

iPTF17bti   0.800077        67.402379       02:38  18.67
pstar=0.957; nuclear/stellar?
iPTF17btj   27.422253       68.506993       02:53  18.34
pstar=0.91; nuclear/stellar?
iPTF17bto   53.02396        70.025567       03:38  17.87
nuclear/stellar?
iPTF17btp   68.216762       72.512217       03:46  19.23
pstar=0.969; nuclear/stellar?
iPTF17bub   85.525185       70.159774       04:32  18.72
pstar=0.946; nuclear/stellar?; fading (0.84 mag intra-night)
iPTF17bue   54.623802       71.407755       03:38  18.04
off-center from host galaxy
iPTF17bun   57.584087       72.275187       03:35  18.63
pstar=0.909; nuclear/stellar?
iPTF17buo   49.553246       73.391128       03:35  18.39
pstar=0.166; nuclear/stellar?; fading (0.69 mag intra-night)
iPTF17buq   41.070946       69.589982       03:28  18.9
pstar=0.996; nuclear/stellar?
iPTF17bvd   83.199221       71.328788       04:32  20.1            hostless
in iPTF reference; possible marginal counterpart seen in PS1.
iPTF17bvw   85.92019        70.584375       04:32  19.74           hostless
in iPTF and PS1
iPTF17bvx   72.69051        69.373832       04:17  19.36
pstar=0.918; nuclear/stellar?
iPTF17bvz   66.258018       69.031885       04:17  19.81
pstar=0.889; nuclear/stellar?
iPTF17bwi   82.2476         71.146032       04:24  20.16
pstar=0.958; nuclear/stellar?
iPTF17bwj   141.533287      7.757573        07:09  19.39   0.441   specz;
nuclear; SDSS QSO
iPTF17bxa   76.262387       69.156295       04:26  19.66           nuclear;
pstar=0.01

Two known transients detected in early January also fall in the
localization region and were recovered with iPTF: PS17m (=iPTF17D) and
PS17n/Gaia17aan (=iPTF17G).

Positions are stated in the ICRS. Discovery times are noted in UTC hh:mm on
2017-03-02. Magnitudes are based on image subtraction and in the Mould R
filter, calibrated with respect to point sources in SDSS as described in
Ofek et al. 2012.

We caution that many candidates are outside the SDSS footprint and lack a
secure star/galaxy classification for the underlying source. We flag these
as "nuclear/stellar?". Where available, we provide machine-learning
probability scores on whether the underlying source is a galaxy/star (0/1)
(Miller et al. 2016).

We encourage spectroscopic classification of these candidates. In
particular, we highlight 17bub and 17buo as fast-evolving by more than 0.3
mag in the same night.

We are grateful to the Palomar crew (John Henning, Jeff Zolkower, Carolyn
Heffner, Jamey Eriksen, Nick Ganciu) for their hard work in reviving a
faulty declination encoder essential to collecting this dataset during the
last two days of iPTF survey operations.

S. Sugita, N. Kawai (Tokyo Tech), M. Serino (RIKEN), H. Negoro (Nihon U.),
S. Ueno, H. Tomida, S. Nakahira, M. Ishikawa, Y. Sugawara (JAXA),
Y. E. Nakagawa (JAMSTEC),
T. Mihara, M. Sugizaki, W. Iwakiri, M. Shidatsu, J. Sugimoto, T.
Takagi, M. Matsuoka (RIKEN),
N.Isobe, T. Yoshii, Y. Tachibana, Y. Ono, T. Fujiwara, S. Harita, Y.
Muraki (Tokyo Tech),
A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Kitaoka (AGU),
H. Tsunemi, R. Shomura (Osaka U.),
M. Nakajima, K. Tanaka, T. Masumitsu, T. Kawase (Nihon U.),
Y. Ueda, T. Kawamuro, T. Hori, A. Tanimoto, S. Oda (Kyoto U.),
Y. Tsuboi, Y. Nakamura, R. Sasaki (Chuo U.),
M. Yamauchi, K. Furuya (Miyazaki U.),
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
G275697 at 2017-02-27 18:57:31.375 UTC (GCN 20763
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 ).

In the 92-min orbit, MAXI/GSC scanned more than 56%
of the whole sky, which includes 52.5% of the
90% regions in the bayestar skymap.
One day image covers 94.1% of the 90% regions
in the bayestar 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 oneday images are
12 (36) mCrab and 3 (9) mCrab, respectively.

P.A. Evans (U. Leicester), J.A. Kennea (PSU), S.D. Barthelmy
(NASA/GSFC), A.P. Beardmore (U. Leicester), A.A. Breeveld (UCL-MSSL),
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. Giommi (ASI), C. Gronwall (PSU), H.A. Krimm
(CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), D.
Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),
B. Mingo (U. Leicester),  J.A. Nousek (PSU), S.R. Oates (U. Warwick),
P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U.
Leicester), K.L. Page (U.Leicester), D.M. Palmer (LANL), 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:

Swift has performed a series of 1372 observations of galaxies (from the
2MPZ catalogue) within the LVC error region for the GW trigger G275697,
using the 'bayestar' GW localisation map. As this is a 3D skymap,
galaxy distances were taken into account in selecting which ones to
observe. The observations currently span from 15 ks to 256 ks after the
LVC trigger, and cover 165 sq degrees on the sky (corrected for
overlaps). This covers 0.16 of the probability in the LVC skymap, and
0.30 of the probability in the LVC map after convolving with the 2MPZ
galaxy catalogue, as described by Evans et al., (2016, MNRAS,  462,
1591).

Since the last Swift GCN, we have detected 6 X-ray sources, these are
either new detections, or have been given a higher 'rank' than in the
last circular. Each source is assigned a rank of 1-4 which describes
how likely it is to be related to the GW trigger, with 1 being the most
likely and 4 being the least likely. The ranks are described at
http://www.swift.ac.uk/ranks.php.

Source 14 was originally reported (in a COUNTERPART) notice as a rank 3
source, as no X-ray counterpart exists in the catalogues searched
automatically. However, an object does exist in the latest 3XMM-DR6
release, which corresponds to source 14, so it has been re-classified
as a rank 4, known source.

Source 8 was also originally reported as rank 3 (LVC Circ. 20798),
however it corresponds to a SIMBAD source 3C 33.1, which is a Seyfert
1, and has been detected by Chandra, therefore this has also been
re-classified as rank 4.

We have found:

  * 0 sources of rank 1
  * 0 sources of rank 2
  * 0 sources of rank 3
  * 6 sources of rank 4

For all flux conversions and comparisons with catalogues and upper
limits from other missions, we assumed a power-law spectrum with
NH=3e20 cm^2, and photon index (Gamma)=1.7


RANK 4 sources
==============

These are catalogued X-ray sources, showing no signs of outburst
compared to previous observations, so they are not likely to be related
to the GW trigger.
  
  Source 9:
  =============
    RA: 	 331.2359 ( = 22h 04m 56.62s) J2000
    Dec:	 +47.2357 ( = +47d 14' 08.5") J2000
    Error:	 +5.5 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.5e-01 +/- 5.6e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 6.6e-12 +/- 2.4e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1SXPS J220456.4+471403 in the 1SXPS catalogue
    Separation:  5.4" from the XRT source
    Cat Rate:	 5.8e-01 +/- 2.7e-02 ct/sec 
    Cat Flux:	 2.5e-11 +/- 1.2e-12 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `V* HK Lac' is 4" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
    NOTE: This source is affected by optical loading. The X-ray
detection appears real, but the flux may be inaccurate.
  
  Source 10:
  =============
    RA: 	 335.0282 ( = 22h 20m 6.77s) J2000
    Dec:	 +49.5037 ( = +49d 30' 13.3") J2000
    Error:	 +8.7 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.5e-01 +/- 5.9e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 6.6e-12 +/- 2.5e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1SXPS J222006.7+493011 in the 1SXPS catalogue
    Separation:  1.6" from the XRT source
    Cat Rate:	 1.5e-01 +/- 1.1e-02 ct/sec 
    Cat Flux:	 6.5e-12 +/- 4.7e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `V* V383 Lac' is 3" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 11:
  =============
    RA: 	 149.3249 ( = 09h 57m 17.98s) J2000
    Dec:	 -13.8334 ( = -13d 50' 00.2") J2000
    Error:	 +6.1 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.5e-02 +/- 1.5e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 1.1e-12 +/- 6.4e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J095718.8-135031 in the ROSAT/RASSFSC catalogue
    Separation:  33.6" from the XRT source
    Cat Rate:	 1.7e-02 +/- 8.0e-03 ct/sec 
    Cat Flux:	 4.9e-13 +/- 2.2e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 0.8-sigma above the catalogued flux.
    The source may be fading, at the 0.3-sigma level.
    There are 2 GWGC or 2MPZ galaxies within 200 kpc of the source.
      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `3FGL J0957.5-1351' is 3.3" away.
  
  Source 12:
  =============
    RA: 	 152.0125 ( = 10h 08m 3.00s) J2000
    Dec:	 -14.9836 ( = -14d 59' 01.0") J2000
    Error:	 +4.6 (arcsec, radius, 90% confidence).
    Peak Rate:	 6.9e-02 +/- 4.1e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 3.0e-12 +/- 1.8e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J100802.7-145904 in the ROSAT/RASSBSC catalogue
    Separation:  5.4" from the XRT source
    Cat Rate:	 2.9e-01 +/- 2.6e-02 ct/sec 
    Cat Flux:	 8.1e-12 +/- 7.4e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    The source may be fading, at the 0.9-sigma level.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `2MASX J10080288-1459066' is 6" away.
    There are 2 2MASS objects within the source's 3-sigma error radius.

  
  Source 13:
  =============
    RA: 	 150.9238 ( = 10h 03m 41.71s) J2000
    Dec:	 -15.1337 ( = -15d 08' 01.3") J2000
    Error:	 +5.6 (arcsec, radius, 90% confidence).
    Peak Rate:	 7.2e-02 +/- 5.5e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 3.1e-12 +/- 2.4e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J100343.2-150820 in the ROSAT/RASSFSC catalogue
    Separation:  28.8" from the XRT source
    Cat Rate:	 4.6e-02 +/- 1.3e-02 ct/sec 
    Cat Flux:	 1.3e-12 +/- 3.8e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 0.8-sigma above the catalogued flux.
    The source may be fading, at the 1.1-sigma level.
    There are 2 GWGC or 2MPZ galaxies within 200 kpc of the source.
      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `[VV96] J100342.1-150808' is 8.2" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 14:
  =============
    RA: 	 0.1318 ( = 00h 00m 31.63s) J2000
    Dec:	 +68.2501 ( = +68d 15' 00.4") J2000
    Error:	 +4.9 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.8e-02 +/- 8.8e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 1.2e-12 +/- 3.8e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:   in the  catalogue
    Separation:  2.0" from the XRT source
    Cat Rate:	 3.7e-01 +/- 7.8e-03 ct/sec 
    Cat Flux:	 9.9e-13 +/- 2.1e-14 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 0.6-sigma above the catalogued flux.
    There is no evidence for fading.
    There are 2 GWGC or 2MPZ galaxies within 200 kpc of the source.
      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `BD+67  1587' is 2" away.
    There is 1 2MASS object within the source's 3-sigma error radius.

This circular is an official product of the Swift team.

C.M.Copperwheat (LJMU), I.A.Steele (LJMU) and A.S.Piascik (LJMU) report 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 report the following Liverpool Telescope follow-up observations of EM
candidates originally reported in GCN #20791
Loading...
 
 . Observations were made with
the SPRAT spectrograph, and supernova classifications were obtained using
SNID (Blondin & Tonry, 2007, ApJ, 666, 1024).


iPTF17bpw was observed on 2017-03-02 at 22:20UT. The transient is centrally
located within its host galaxy and the spectrum shows strong emission lines
indicative of an AGN.

iPTF17bou was observed on 2017-03-02 at 22:53UT. We tentatively classify
this transient as a type II SN at +58 days with z=0.131.

P.A. Evans (U. Leicester), J.A. Kennea (PSU), S.D. Barthelmy
(NASA/GSFC), A.P. Beardmore (U. Leicester), A.A. Breeveld (UCL-MSSL),
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. Giommi (ASI), C. Gronwall (PSU), H.A. Krimm
(CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), D.
Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),
B. Mingo (U. Leicester),  J.A. Nousek (PSU), S.R. Oates (U. Warwick),
P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U.
Leicester), K.L. Page (U.Leicester), D.M. Palmer (LANL), 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:

Swift has performed a series of 1385 observations of galaxies (from the
2MPZ catalogue) within the LVC error region for the GW trigger G275697,
using the 'bayestar' GW localisation map. As this is a 3D skymap,
galaxy distances were taken into account in selecting which ones to
observe. The observations currently span from 15 ks to 350 ks after the
LVC trigger, and cover 167 sq degrees on the sky (corrected for
overlaps). This covers 0.16 of the probability in the LVC skymap, and
0.30 of the probability in the LVC map after convolving with the 2MPZ
galaxy catalogue, as described by Evans et al., (2016, MNRAS,  462,
1591).

Since the last Swift GCN, we have detected 15 X-ray sources, these are
either new detections, or have been given a higher 'rank' than in the
last circular. Each source is assigned a rank of 1-4 which describes
how likely it is to be related to the GW trigger, with 1 being the most
likely and 4 being the least likely. The ranks are described at
http://www.swift.ac.uk/ranks.php.

Many more sources were reported via GCN/LVC_COUNTERPART notices, which
had the "WARN_FLAG" field set to 1, indicating that the automatic
detection system considered the sources may be spurious. Manual
inspection has confirmed these sources are not real, but were caused by
stray light - singly-reflected X-rays from a bright, off-axis source.
See http://www.swift.ac.uk/1SXPS/construct.php#fig5 more details.


The new, manually verified sources comprise:

  * 0 sources of rank 1
  * 0 sources of rank 2
  * 6 sources of rank 3
  * 9 sources of rank 4

For all flux conversions and comparisons with catalogues and upper
limits from other missions, we assumed a power-law spectrum with
NH=3e20 cm^2, and photon index (Gamma)=1.7


RANK 3 sources
==============

These are uncatalogued X-ray sources, however they are not brighter
than previous upper limits, so do not stand out as likely counterparts
to the GW trigger.
  
  Source 18:
  =============
    RA: 	 230.8241 ( = 15h 23m 17.78s) J2000
    Dec:	 -50.4510 ( = -50d 27' 03.6") J2000
    Error:	 +6.2 (arcsec, radius, 90% confidence).
    Peak Rate:	 3.7e-02 +/- 1.2e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 1.6e-12 +/- 5.0e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 2.6e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)

       so the source is not above the RASS 3-sigma upper limit.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    There are 3 2MASS objects within the source's 3-sigma error radius.

  
  Source 19:
  =============
    RA: 	 221.4244 ( = 14h 45m 41.86s) J2000
    Dec:	 -49.3746 ( = -49d 22' 28.6") J2000
    Error:	 +6.7 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.9e-02 +/- 8.1e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 8.2e-13 +/- 3.5e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 2.2e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)

       so the source is not above the RASS 3-sigma upper limit.
    There is no evidence for fading.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
  
  Source 23:
  =============
    RA: 	 323.3099 ( = 21h 33m 14.38s) J2000
    Dec:	 +39.6853 ( = +39d 41' 07.1") J2000
    Error:	 +5.5 (arcsec, radius, 90% confidence).
    Peak Rate:	 6.4e-02 +/- 3.9e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 2.8e-12 +/- 1.7e-12 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 1.6e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)

       so the source is not above the RASS 3-sigma upper limit.
    The source may be fading, at the 1.5-sigma level.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 24:
  =============
    RA: 	 142.4443 ( = 09h 29m 46.63s) J2000
    Dec:	 +2.0633 ( = +02d 03' 47.9") J2000
    Error:	 +6.0 (arcsec, radius, 90% confidence).
    Peak Rate:	 5.4e-02 +/- 4.1e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 2.3e-12 +/- 1.8e-12 erg cm^-2 s^-1 (0.3-10 keV)
    1XMM UL:	5.7e-12 ct/sec, (0.3-10 keV)
       so the source is 1.9-sigma above the XMM 3-sigma upper limit.
    RASS UL:	 1.7e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)

       so the source is not above the RASS 3-sigma upper limit.
    The source may be fading, at the 0.9-sigma level.
    There are 5 GWGC or 2MPZ galaxies within 200 kpc of the source.
      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `NGC  2898' is 6.3" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 25:
  =============
    RA: 	 154.6980 ( = 10h 18m 47.52s) J2000
    Dec:	 -18.5442 ( = -18d 32' 39.1") J2000
    Error:	 +5.1 (arcsec, radius, 90% confidence).
    Peak Rate:	 4.6e-02 +/- 3.4e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 2.0e-12 +/- 1.5e-12 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 2.1e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)

       so the source is not above the RASS 3-sigma upper limit.
    The source may be fading, at the 1.2-sigma level.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
  
  Source 30:
  =============
    RA: 	 150.6904 ( = 10h 02m 45.70s) J2000
    Dec:	 -16.1968 ( = -16d 11' 48.5") J2000
    Error:	 +5.6 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.0e-02 +/- 8.5e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 8.6e-13 +/- 3.7e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 1.7e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)

       so the source is not above the RASS 3-sigma upper limit.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.


RANK 4 sources
==============

These are catalogued X-ray sources, showing no signs of outburst
compared to previous observations, so they are not likely to be related
to the GW trigger.
  
  Source 15:
  =============
    RA: 	 175.6993 ( = 11h 42m 47.83s) J2000
    Dec:	 -35.8159 ( = -35d 48' 57.2") J2000
    Error:	 +4.7 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.2e-01 +/- 5.9e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 5.0e-12 +/- 2.6e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  XMMSL1 J114247.5-354904 in the XMM-NEWTON/XMMSLEWCLN
catalogue
    Separation:  8.8" from the XRT source
    Cat Rate:	 0.0e+00 +/- 0.0e+00 ct/sec 
    Cat Flux:	 0.0e+00 +/- 0.0e+00 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    The source may be fading, at the 1.3-sigma level.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `V* V752 Cen' is 3" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 16:
  =============
    RA: 	 333.9766 ( = 22h 15m 54.38s) J2000
    Dec:	 +52.3104 ( = +52d 18' 37.4") J2000
    Error:	 +6.1 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.5e-02 +/- 6.4e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 6.5e-13 +/- 2.8e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J221553.6+521752 in the ROSAT/RASSFSC catalogue
    Separation:  46.2" from the XRT source
    Cat Rate:	 2.4e-02 +/- 6.8e-03 ct/sec 
    Cat Flux:	 6.8e-13 +/- 1.9e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    There are 2 2MASS objects within the source's 3-sigma error radius.

  
  Source 17:
  =============
    RA: 	 335.0252 ( = 22h 20m 6.05s) J2000
    Dec:	 +53.0105 ( = +53d 00' 37.8") J2000
    Error:	 +8.6 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.5e-02 +/- 6.9e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 6.3e-13 +/- 3.0e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J222010.7+530025 in the ROSAT/RASSFSC catalogue
    Separation:  43.8" from the XRT source
    Cat Rate:	 1.9e-02 +/- 6.4e-03 ct/sec 
    Cat Flux:	 5.2e-13 +/- 1.8e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 0.3-sigma above the catalogued flux.
    There is no evidence for fading.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
    There are 6 2MASS objects within the source's 3-sigma error radius.

  
  Source 20:
  =============
    RA: 	 146.7595 ( = 09h 47m 2.28s) J2000
    Dec:	 -5.9474 ( = -05d 56' 50.6") J2000
    Error:	 +5.7 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.7e-02 +/- 8.9e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 7.3e-13 +/- 3.8e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  XMMSL1 J094702.8-055704 in the XMM-NEWTON/XMMSLEWCLN
catalogue
    Separation:  15.8" from the XRT source
    Cat Rate:	 5.9e-01 +/- 2.1e-01 ct/sec 
    Cat Flux:	 5.9e-12 +/- 2.1e-12 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    There is no evidence for fading.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `LEDA 1038543' is 8.3" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 21:
  =============
    RA: 	 152.9971 ( = 10h 11m 59.30s) J2000
    Dec:	 -16.6088 ( = -16d 36' 31.7") J2000
    Error:	 +5.0 (arcsec, radius, 90% confidence).
    Peak Rate:	 3.9e-02 +/- 1.1e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 1.7e-12 +/- 4.6e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J101158.2-163617 in the ROSAT/RASSFSC catalogue
    Separation:  21.1" from the XRT source
    Cat Rate:	 3.7e-02 +/- 1.1e-02 ct/sec 
    Cat Flux:	 1.0e-12 +/- 3.1e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 1.1-sigma above the catalogued flux.
    There is no evidence for fading.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `2MASX J10115905-1636329' is 3.7" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 22:
  =============
    RA: 	 227.5239 ( = 15h 10m 5.74s) J2000
    Dec:	 -50.8594 ( = -50d 51' 33.8") J2000
    Error:	 +5.9 (arcsec, radius, 90% confidence).
    Peak Rate:	 9.4e-02 +/- 4.8e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 4.0e-12 +/- 2.1e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J151006.2-505125 in the ROSAT/RASSFSC catalogue
    Separation:  9.7" from the XRT source
    Cat Rate:	 2.4e-02 +/- 1.1e-02 ct/sec 
    Cat Flux:	 6.7e-13 +/- 3.1e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 1.6-sigma above the catalogued flux.
    The source may be fading, at the 2.0-sigma level.
    There are 2 GWGC or 2MPZ galaxies within 200 kpc of the source.
      and consistent (within 3-sigma) with the distance to the GW
object.
    There are 4 2MASS objects within the source's 3-sigma error radius.

  
  Source 27:
  =============
    RA: 	 314.7183 ( = 20h 58m 52.39s) J2000
    Dec:	 +31.5034 ( = +31d 30' 12.2") J2000
    Error:	 +5.8 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.7e-02 +/- 6.3e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 7.5e-13 +/- 2.7e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  2E 2056.7+3118 in the EINSTEIN/EINSTEIN2E catalogue
    Separation:  9.9" from the XRT source
    Cat Rate:	 1.6e-02 +/- 3.2e-03 ct/sec 
    Cat Flux:	 7.7e-13 +/- 1.5e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    There are 2 2MASS objects within the source's 3-sigma error radius.

  
  Source 29:
  =============
    RA: 	 318.4372 ( = 21h 13m 44.93s) J2000
    Dec:	 +35.5312 ( = +35d 31' 52.3") J2000
    Error:	 +6.1 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.7e-02 +/- 9.6e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 1.1e-12 +/- 4.1e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J211341.2+353144 in the ROSAT/RASSFSC catalogue
    Separation:  46.3" from the XRT source
    Cat Rate:	 2.2e-02 +/- 9.5e-03 ct/sec 
    Cat Flux:	 6.2e-13 +/- 2.7e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 1.0-sigma above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 32:
  =============
    RA: 	 155.8947 ( = 10h 23m 34.73s) J2000
    Dec:	 -19.5432 ( = -19d 32' 35.5") J2000
    Error:	 +5.2 (arcsec, radius, 90% confidence).
    Peak Rate:	 5.3e-02 +/- 4.0e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 2.3e-12 +/- 1.7e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J102335.1-193240 in the ROSAT/RASSFSC catalogue
    Separation:  7.2" from the XRT source
    Cat Rate:	 2.1e-02 +/- 9.2e-03 ct/sec 
    Cat Flux:	 5.9e-13 +/- 2.6e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 1.0-sigma above the catalogued flux.
    The source may be fading, at the 1.3-sigma level.
    There are 2 GWGC or 2MPZ galaxies within 200 kpc of the source.
      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `TYC 6068-295-1' is 4.4" away.
    There is 1 2MASS object within the source's 3-sigma error radius.

This circular is an official product of the Swift team.

C.M.Copperwheat (LJMU), I.A.Steele (LJMU) and A.S.Piascik (LJMU) report 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 report the following Liverpool Telescope follow-up observations of an EM
candidate originally reported in GCN #20802
Loading...
 
 . Observations were made with
the SPRAT spectrograph.


iPTF17buo was observed on 2017-03-03 at 21:33UT. We find a mostly
featureless spectrum with weak Halpha and Hbeta in absorption, so we
believe this source to be a dwarf nova in outburst.

K. De, N. Blagorodnova, R. Lunnan, M. Balokovic, N. Kamraj, M. Heida, D.
Stern and M. M. Kasliwal (Caltech)

report on behalf of the iPTF (intermediate Palomar Transient Factory) and
GROWTH (Global Relay of Observatories Watching Transients Happen)
collaborations

On UT 2017-03-04, we spectroscopically classified the following optical
transient candidates (LVC GCN#20802
Loading...
 
 , LVC GCN#20791
Loading...
 
 ) using the Double Beam
Spectrograph (Oke & Gunn 1982) on the Palomar 200-inch Hale Telescope. All
spectra were reduced using the pyraf-dbsp pipeline (Bellm & Sesar 2016).
Classification were done with SNID (Blondin & Tonry, 2007) and Superfit
(Howell et al. 2005).

Name, Redshift, Classification, Notes
iPTF17bue, z=0.02, SN Ia, Best match is SN2005cf at +4d
iPTF17buo, z=0, CV, Consistent with LVC GCN#20815
Loading...
 
 
iPTF17bti, z=0, CV
iPTF17bxa, z=0.076, Spectrum dominated by galaxy light
iPTF17bub, z=0, M-dwarf flare
iPTF17btx, z=0.022, SN II, just outside 90% contour line
iPTF17bvw, z=0.132, SN Ia, Best match is SN2003du +0d
iPTF17bvd, Unknown, Blue Featureless Spectrum
iPTF17bva, z=0.112, SN Ia, Best match is SN1990N at -7d, just outside 90%
contour line

P.A. Evans (U. Leicester), J.A. Kennea (PSU), S.D. Barthelmy
(NASA/GSFC), A.P. Beardmore (U. Leicester), A.A. Breeveld (UCL-MSSL),
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. Giommi (ASI), C. Gronwall (PSU), H.A. Krimm
(CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), D.
Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),
B. Mingo (U. Leicester),  J.A. Nousek (PSU), S.R. Oates (U. Warwick),
P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U.
Leicester), K.L. Page (U.Leicester), D.M. Palmer (LANL), 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:

Swift has performed a series of 1751 observations, covering 1408
separate locations within the LVC error region for the GW trigger
G275697 convolved with the 2MPZ catalogue, using the 'bayestar' GW
localisation map. As this is a 3D skymap, galaxy distances were taken
into account in selecting which ones to observe. The observations
currently span from 15 ks to 534 ks after the LVC trigger, and cover
171 sq degrees on the sky (corrected for overlaps). This covers 0.16 of
the probability in the LVC skymap, and 0.31 of the probability in the
LVC map after convolving with the 2MPZ galaxy catalogue, as described
by Evans et al., (2016, MNRAS,	462, 1591).

Since the last Swift GCN, we have detected 31 X-ray sources, these are
either new detections, or have been given a higher 'rank' than in the
last circular. Each source is assigned a rank of 1-4 which describes
how likely it is to be related to the GW trigger, with 1 being the most
likely and 4 being the least likely. The ranks are described at
http://www.swift.ac.uk/ranks.php.

We have found:

  * 0 sources of rank 1
  * 0 sources of rank 2
  * 12 sources of rank 3
  * 19 sources of rank 4

For all flux conversions and comparisons with catalogues and upper
limits from other missions, we assumed a power-law spectrum with
NH=3e20 cm^2, and photon index (Gamma)=1.7


RANK 3 sources
==============

These are uncatalogued X-ray sources, however they are not brighter
than previous upper limits, so do not stand out as likely counterparts
to the GW trigger.
  
  Source 75:
  =============
    RA: 	 331.8734 ( = 22h 07m 29.62s) J2000
    Dec:	 +49.5170 ( = +49d 31' 01.2") J2000
    Error:	 +6.2 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.4e-02 +/- 8.1e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 1.0e-12 +/- 3.5e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 2.8e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)
       so the source is not above the RASS 3-sigma upper limit.
    There is no evidence for fading.
    There are 2 GWGC or 2MPZ galaxies within 200 kpc of the source.
      and consistent (within 3-sigma) with the distance to the GW
object.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 78:
  =============
    RA: 	 332.0579 ( = 22h 08m 13.90s) J2000
    Dec:	 +53.1143 ( = +53d 06' 51.5") J2000
    Error:	 +5.9 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.6e-02 +/- 7.0e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 7.1e-13 +/- 3.0e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 1.2e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)
       so the source is not above the RASS 3-sigma upper limit.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    There are 2 2MASS objects within the source's 3-sigma error radius.
  
  Source 88:
  =============
    RA: 	 319.2979 ( = 21h 17m 11.50s) J2000
    Dec:	 +36.0755 ( = +36d 04' 31.8") J2000
    Error:	 +5.6 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.3e-02 +/- 9.0e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 9.9e-13 +/- 3.8e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 1.9e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)
       so the source is not above the RASS 3-sigma upper limit.
    The source may be fading, at the 0.7-sigma level.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `TYC 2714-1267-1' is 2.9" away.
    There are 2 2MASS objects within the source's 3-sigma error radius.
  
  Source 89:
  =============
    RA: 	 337.1248 ( = 22h 28m 29.95s) J2000
    Dec:	 +53.7363 ( = +53d 44' 10.7") J2000
    Error:	 +5.4 (arcsec, radius, 90% confidence).
    Peak Rate:	 3.4e-02 +/- 9.9e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 1.4e-12 +/- 4.3e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 1.7e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)
       so the source is not above the RASS 3-sigma upper limit.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 100:
  =============
    RA: 	 321.1287 ( = 21h 24m 30.89s) J2000
    Dec:	 +40.2662 ( = +40d 15' 58.3") J2000
    Error:	 +6.2 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.2e-02 +/- 6.4e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 5.0e-13 +/- 2.7e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 1.1e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)
       so the source is not above the RASS 3-sigma upper limit.
    There is no evidence for fading.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 102:
  =============
    RA: 	 185.8256 ( = 12h 23m 18.14s) J2000
    Dec:	 -44.6254 ( = -44d 37' 31.4") J2000
    Error:	 +6.4 (arcsec, radius, 90% confidence).
    Peak Rate:	 3.1e-02 +/- 1.2e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 1.3e-12 +/- 5.1e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 3.5e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)
       so the source is not above the RASS 3-sigma upper limit.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 104:
  =============
    RA: 	 314.1185 ( = 20h 56m 28.44s) J2000
    Dec:	 +30.7549 ( = +30d 45' 17.6") J2000
    Error:	 +6.1 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.5e-02 +/- 1.2e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 1.1e-12 +/- 5.1e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 1.8 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)
       so the source is not above the RASS 3-sigma upper limit.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
  
  Source 108:
  =============
    RA: 	 317.9252 ( = 21h 11m 42.05s) J2000
    Dec:	 +32.9903 ( = +32d 59' 25.1") J2000
    Error:	 +7.2 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.9e-02 +/- 8.2e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 8.3e-13 +/- 3.5e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 1.6e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)
       so the source is not above the RASS 3-sigma upper limit.
    There is no evidence for fading.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `NVSS J211141+325922' is 3.3" away.
    There are 3 2MASS objects within the source's 3-sigma error radius.
  
  Source 109:
  =============
    RA: 	 317.9797 ( = 21h 11m 55.13s) J2000
    Dec:	 +32.7464 ( = +32d 44' 47.0") J2000
    Error:	 +6.4 (arcsec, radius, 90% confidence).
    Peak Rate:	 3.1e-02 +/- 1.1e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 1.3e-12 +/- 4.9e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 2.5e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)
       so the source is not above the RASS 3-sigma upper limit.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 113:
  =============
    RA: 	 338.0488 ( = 22h 32m 11.71s) J2000
    Dec:	 +54.1364 ( = +54d 08' 11.0") J2000
    Error:	 +4.7 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.8e-02 +/- 5.4e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 7.9e-13 +/- 2.3e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 1.8e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)
       so the source is not above the RASS 3-sigma upper limit.
    There is no evidence for fading.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
    There are 2 2MASS objects within the source's 3-sigma error radius.
  
  Source 114:
  =============
    RA: 	 149.5567 ( = 09h 58m 13.61s) J2000
    Dec:	 -5.4085 ( = -05d 24' 30.6") J2000
    Error:	 +6.0 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.9e-02 +/- 7.9e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 8.1e-13 +/- 3.4e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 4.3e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)
       so the source is not above the RASS 3-sigma upper limit.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `2dFGRS TGN093Z309' is 8.5" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 115:
  =============
    RA: 	 335.3673 ( = 22h 21m 28.15s) J2000
    Dec:	 +50.5456 ( = +50d 32' 44.2") J2000
    Error:	 +6.2 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.5e-02 +/- 7.1e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 6.5e-13 +/- 3.0e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 9.9e-03 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)
       so the source is not above the RASS 3-sigma upper limit.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    There is 1 2MASS object within the source's 3-sigma error radius.


RANK 4 sources
==============

These are catalogued X-ray sources, showing no signs of outburst
compared to previous observations, so they are not likely to be related
to the GW trigger.
  
  Source 74:
  =============
    RA: 	 331.9459 ( = 22h 07m 47.02s) J2000
    Dec:	 +49.5290 ( = +49d 31' 44.4") J2000
    Error:	 +5.3 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.1e-02 +/- 7.7e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 9.1e-13 +/- 3.3e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J220747.1+493153 in the ROSAT/RASSFSC catalogue
    Separation:  8.7" from the XRT source
    Cat Rate:	 4.6e-02 +/- 1.0e-02 ct/sec 
    Cat Flux:	 1.3e-12 +/- 2.9e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    There is no evidence for fading.
    There are 3 GWGC or 2MPZ galaxies within 200 kpc of the source.
      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `TYC 3614-2026-1' is 5.2" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 76:
  =============
    RA: 	 162.7383 ( = 10h 50m 57.19s) J2000
    Dec:	 -28.8335 ( = -28d 50' 00.6") J2000
    Error:	 +5.1 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.8e-02 +/- 8.3e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 7.7e-13 +/- 3.6e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J105057.2-284954 in the ROSAT/RASSBSC catalogue
    Separation:  6.5" from the XRT source
    Cat Rate:	 5.4e-02 +/- 1.4e-02 ct/sec 
    Cat Flux:	 1.5e-12 +/- 3.9e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `CD-28  8475' is 5" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 77:
  =============
    RA: 	 169.9411 ( = 11h 19m 45.86s) J2000
    Dec:	 -34.5976 ( = -34d 35' 51.4") J2000
    Error:	 +6.8 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.9e-02 +/- 9.0e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 8.3e-13 +/- 3.9e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  XMMSL1 J111946.5-343602 in the XMM-NEWTON/XMMSLEWCLN
catalogue
    Separation:  12.8" from the XRT source
    Cat Rate:	 6.6e-01 +/- 2.1e-01 ct/sec 
    Cat Flux:	 6.6e-12 +/- 2.1e-12 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    There is no evidence for fading.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `1RXS J111945.5-343544' is 8.3" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 82:
  =============
    RA: 	 325.2405 ( = 21h 40m 57.72s) J2000
    Dec:	 +38.2968 ( = +38d 17' 48.5") J2000
    Error:	 +7.2 (arcsec, radius, 90% confidence).
    Peak Rate:	 6.0e-02 +/- 1.5e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 2.6e-12 +/- 6.5e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J214053.8+381749 in the ROSAT/RASSFSC catalogue
    Separation:  46.0" from the XRT source
    Cat Rate:	 3.0e-02 +/- 9.2e-03 ct/sec 
    Cat Flux:	 8.5e-13 +/- 2.6e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 2.5-sigma above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 90:
  =============
    RA: 	 337.3447 ( = 22h 29m 22.73s) J2000
    Dec:	 +53.8290 ( = +53d 49' 44.4") J2000
    Error:	 +5.3 (arcsec, radius, 90% confidence).
    Peak Rate:	 3.2e-02 +/- 1.0e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 1.4e-12 +/- 4.5e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J222920.8+534939 in the ROSAT/RASSFSC catalogue
    Separation:  18.0" from the XRT source
    Cat Rate:	 3.5e-02 +/- 9.6e-03 ct/sec 
    Cat Flux:	 9.7e-13 +/- 2.7e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 0.8-sigma above the catalogued flux.
    There is no evidence for fading.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
  
  Source 91:
  =============
    RA: 	 153.2726 ( = 10h 13m 5.42s) J2000
    Dec:	 -16.6892 ( = -16d 41' 21.1") J2000
    Error:	 +6.7 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.6e-02 +/- 7.6e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 7.0e-13 +/- 3.3e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J101305.6-164124 in the ROSAT/RASSBSC catalogue
    Separation:  3.9" from the XRT source
    Cat Rate:	 7.4e-02 +/- 1.5e-02 ct/sec 
    Cat Flux:	 2.1e-12 +/- 4.1e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `1RXS J101305.6-164124' is 3.8" away.
  
  Source 92:
  =============
    RA: 	 153.7642 ( = 10h 15m 3.41s) J2000
    Dec:	 -16.8695 ( = -16d 52' 10.2") J2000
    Error:	 +4.8 (arcsec, radius, 90% confidence).
    Peak Rate:	 3.4e-02 +/- 1.1e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 1.4e-12 +/- 4.7e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J101502.3-165219 in the ROSAT/RASSBSC catalogue
    Separation:  18.0" from the XRT source
    Cat Rate:	 6.8e-02 +/- 1.4e-02 ct/sec 
    Cat Flux:	 1.9e-12 +/- 4.1e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `[VV96] J101503.2-165215' is 4.8" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 93:
  =============
    RA: 	 320.2548 ( = 21h 21m 1.15s) J2000
    Dec:	 +40.3434 ( = +40d 20' 36.2") J2000
    Error:	 +4.5 (arcsec, radius, 90% confidence).
    Peak Rate:	 7.7e-02 +/- 3.5e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 3.3e-12 +/- 1.5e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1SXPS J212101.4+402040 in the 1SXPS catalogue
    Separation:  5.2" from the XRT source
    Cat Rate:	 9.7e-02 +/- 6.6e-03 ct/sec 
    Cat Flux:	 4.2e-12 +/- 2.8e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    The source may be fading, at the 0.6-sigma level.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `HR  8170' is 6.8" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
    NOTE: This source is affected by optical loading. The X-ray
detection appears real, but the flux may be inaccurate.
  
  Source 99:
  =============
    RA: 	 332.2250 ( = 22h 08m 54.00s) J2000
    Dec:	 +50.8409 ( = +50d 50' 27.2") J2000
    Error:	 +5.3 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.2e-02 +/- 7.6e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 9.4e-13 +/- 3.3e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J220855.0+505022 in the ROSAT/RASSFSC catalogue
    Separation:  10.8" from the XRT source
    Cat Rate:	 2.6e-02 +/- 8.6e-03 ct/sec 
    Cat Flux:	 7.3e-13 +/- 2.4e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 0.5-sigma above the catalogued flux.
    There is no evidence for fading.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `TYC 3618-4068-1' is 1.3" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 101:
  =============
    RA: 	 156.2197 ( = 10h 24m 52.73s) J2000
    Dec:	 -19.9373 ( = -19d 56' 14.3") J2000
    Error:	 +6.8 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.8e-02 +/- 7.7e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 7.9e-13 +/- 3.3e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J102453.0-195618 in the ROSAT/RASSFSC catalogue
    Separation:  5.4" from the XRT source
    Cat Rate:	 2.4e-02 +/- 9.8e-03 ct/sec 
    Cat Flux:	 6.8e-13 +/- 2.8e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 0.3-sigma above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `1RXS J102453.0-195618' is 5.4" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 103:
  =============
    RA: 	 182.5174 ( = 12h 10m 4.18s) J2000
    Dec:	 -46.6067 ( = -46d 36' 24.1") J2000
    Error:	 +4.3 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.1e-01 +/- 2.0e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 4.9e-12 +/- 8.4e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1SXPS J121004.1-463628 in the 1SXPS catalogue
    Separation:  4.2" from the XRT source
    Cat Rate:	 9.1e-02 +/- 4.7e-03 ct/sec 
    Cat Flux:	 3.9e-12 +/- 2.0e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 1.1-sigma above the catalogued flux.
    There is no evidence for fading.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `6dFGS gJ121004.0-463627' is 3.7" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 106:
  =============
    RA: 	 338.9167 ( = 22h 35m 40.01s) J2000
    Dec:	 +53.7587 ( = +53d 45' 31.3") J2000
    Error:	 +6.2 (arcsec, radius, 90% confidence).
    Peak Rate:	 5.4e-02 +/- 4.1e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 2.3e-12 +/- 1.8e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J223540.8+534546 in the ROSAT/RASSFSC catalogue
    Separation:  16.8" from the XRT source
    Cat Rate:	 2.8e-02 +/- 8.6e-03 ct/sec 
    Cat Flux:	 7.9e-13 +/- 2.4e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 0.9-sigma above the catalogued flux.
    The source may be fading, at the 1.2-sigma level.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `2MASS J22354027+5345341' is 3.7" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 110:
  =============
    RA: 	 182.8138 ( = 12h 11m 15.31s) J2000
    Dec:	 -46.6922 ( = -46d 41' 31.9") J2000
    Error:	 +7.0 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.2e-02 +/- 9.2e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 9.2e-13 +/- 4.0e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1SXPS J121115.7-464136 in the 1SXPS catalogue
    Separation:  6.3" from the XRT source
    Cat Rate:	 1.6e-03 +/- 7.3e-04 ct/sec 
    Cat Flux:	 6.8e-14 +/- 3.1e-14 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 2.2-sigma above the catalogued flux.
    There is no evidence for fading.
    There are 5 GWGC or 2MPZ galaxies within 200 kpc of the source.
      and consistent (within 3-sigma) with the distance to the GW
object.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 111:
  =============
    RA: 	 149.6399 ( = 09h 58m 33.58s) J2000
    Dec:	 -5.3605 ( = -05d 21' 37.8") J2000
    Error:	 +4.7 (arcsec, radius, 90% confidence).
    Peak Rate:	 6.9e-02 +/- 4.2e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 3.0e-12 +/- 1.8e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J095829.9-052126 in the ROSAT/RASSFSC catalogue
    Separation:  56.3" from the XRT source
    Cat Rate:	 4.0e-02 +/- 1.8e-02 ct/sec 
    Cat Flux:	 1.1e-12 +/- 5.0e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 1.0-sigma above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 112:
  =============
    RA: 	 338.1576 ( = 22h 32m 37.82s) J2000
    Dec:	 +54.0915 ( = +54d 05' 29.4") J2000
    Error:	 +5.6 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.2e-02 +/- 7.9e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 9.4e-13 +/- 3.4e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  XMMSL1 J223237.3+540522 in the XMM-NEWTON/XMMSLEWCLN
catalogue
    Separation:  8.4" from the XRT source
    Cat Rate:	 7.1e-01 +/- 3.1e-01 ct/sec 
    Cat Flux:	 7.1e-12 +/- 3.1e-12 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    There is no evidence for fading.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `TYC 3983-1532-1' is 2.1" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 116:
  =============
    RA: 	 314.5512 ( = 20h 58m 12.29s) J2000
    Dec:	 +30.0769 ( = +30d 04' 36.8") J2000
    Error:	 +4.3 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.0e-01 +/- 1.7e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 4.3e-12 +/- 7.3e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  XMMSL1 J205812.3+300431 in the XMM-NEWTON/XMMSLEWCLN
catalogue
    Separation:  6.5" from the XRT source
    Cat Rate:	 1.5e+00 +/- 5.0e-01 ct/sec 
    Cat Flux:	 1.5e-11 +/- 5.0e-12 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    There is no evidence for fading.
    There is 1 GWGC or 2MPZ galaxy within 200 kpc of the source.

      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `2MASS J20581235+3004372' is 0.7" away.
    There are 2 2MASS objects within the source's 3-sigma error radius.
  
  Source 117:
  =============
    RA: 	 328.3164 ( = 21h 53m 15.94s) J2000
    Dec:	 +47.7302 ( = +47d 43' 48.7") J2000
    Error:	 +5.2 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.3e-02 +/- 9.5e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 9.7e-13 +/- 4.1e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  2RXP J215317.0+474351 in the ROSAT/ROSPSPC catalogue
    Separation:  10.6" from the XRT source
    Cat Rate:	 1.9e-02 +/- 0.0e+00 ct/sec 
    Cat Flux:	 5.4e-13 +/- 0.0e+00 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 1.1-sigma above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `BD+47  3593' is 2.9" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 118:
  =============
    RA: 	 169.5633 ( = 11h 18m 15.19s) J2000
    Dec:	 -32.8034 ( = -32d 48' 12.2") J2000
    Error:	 +6.5 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.0e-02 +/- 7.9e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 8.7e-13 +/- 3.4e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1SXPS J111815.4-324819 in the 1SXPS catalogue
    Separation:  8.3" from the XRT source
    Cat Rate:	 2.6e-03 +/- 1.6e-03 ct/sec 
    Cat Flux:	 1.1e-13 +/- 6.9e-14 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 2.2-sigma above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `[BKM2001]	8' is 8.8" away.
  
  Source 119:
  =============
    RA: 	 321.8103 ( = 21h 27m 14.47s) J2000
    Dec:	 +39.2096 ( = +39d 12' 34.6") J2000
    Error:	 +6.0 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.6e-02 +/- 6.8e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 6.8e-13 +/- 2.9e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J212713.9+391247 in the ROSAT/RASSFSC catalogue
    Separation:  14.1" from the XRT source
    Cat Rate:	 2.2e-02 +/- 8.2e-03 ct/sec 
    Cat Flux:	 6.1e-13 +/- 2.3e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 0.2-sigma above the catalogued flux.
    There is no evidence for fading.
    There are 2 GWGC or 2MPZ galaxies within 200 kpc of the source.
      and consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `TYC 3182-1546-1' is 6.8" away.
    There is 1 2MASS object within the source's 3-sigma error radius.

This circular is an official product of the Swift team.

The LIGO Scientific Collaboration and Virgo report:

We have completed an initial Bayesian parameter estimation analysis of the
LIGO data around the time of the compact binary coalescence (CBC) event
candidate G275697 (GCN 20763
Loading...
 
 ) using LALInference (Veitch et al., PRD 91,
042003). This analysis used the IMRPhenomPv2 waveform approximant, which
includes the inspiral, merger, and ringdown phases of the signal and
accounts for the effects of spin precession. We accounted for systematic
errors due to uncertainty in the calibration of the detectors' responses
of up to 10% in amplitude and 10 degrees in phase.

This parameter estimation analysis does not influence our estimation of
the significance of this event. It remains a marginal candidate with a
false alarm rate of about one in two months as reported in our original
Circular. If the signal is astrophysical, then the mass estimates are
consistent with a NSNS or NSBH binary.

An updated localization, LALInference.fits.gz, is available for retrieval
from the GraceDB event page:

https://gracedb.ligo.org/events/G275697

This is the preferred sky map at this time. The localization is similar to
the rapid BAYESTAR sky map, but it is coarser due to the inclusion of
systematic errors due to calibration. The 50% credible region spans 1020
deg2 and the 90% credible region spans 3890 deg2. The luminosity distance
is found to be 193 +/- 61 Mpc (mean +/- std. dev.).

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

P.A. Evans (U. Leicester), A.A. Breeveld (UCL-MSSL), J.A. Kennea (PSU), 
S.D. Barthelmy (NASA/GSFC), 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. Giommi (ASI), C. Gronwall (PSU), H.A. Krimm 
(CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), D.
Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), 
B. Mingo (U. Leicester), J.A. Nousek (PSU), S.R. Oates (U. Warwick), 
P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U. 
Leicester), K.L. Page (U.Leicester), D.M. Palmer (LANL), 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:

Swift is conducting further observations of the 'rank 3' X-ray sources
detected in our initial search of the LIGO/VIRGO error region. These are 
uncatalogued X-ray sources which are below existing catalogue limits and 
therefore cannot be distinguished as new or pre-existing sources.

Source 23 (Evans et al, LVC Circ. 20812) appears to be fading. This 
source has now been observed three times, and a power-law fit to the 
light curves gives a slope of alpha=0.87 +/- 0.26 (1-sigma errors), i.e. 
the fading is confirmed with 3.5-sigma significance. Follow-up
observations of this source at other wavelengths are strongly 
encouraged. The UVOT-enhanced position of this source is:

RA (J2000.0):  21h 33m 14.96s = 323.31234 degrees
Dec (J2000.0): +39d 41' 09.2" = 39.68590 degrees

with an uncertainty of 4.4 arcsec (radius, 90% confidence).

Swift-UVOT observed this field in the u and uvw1 filters. No new source 
is detected to 3-sigma upper limits of 19.3 mag (u) and 19.9 mag (uvw1), 
but the position is just 10.7 arcsec from the B=12.3 mag source 
USNO-B1.0 1296-047182, so these upper limits are approximate.

X-ray Sources 1,8,14 and 18 have also been re-observed and are found to 
be ~constant and are therefore unlikely to be related to the GW event. 
Source 19 has been re-observed, but at present we cannot ascertain 
whether or not it is fading.

This circular is an official product of the Swift-XRT team.

Daniele Malesani (DARK/NBI), Elena Pian (SNS), L. Amati (INAF-IASF Bo), 
L. A. Antonelli, S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC), M. 
Branchesi (Urbino University/INFN Firenze), S. Campana (INAF-OABr), E. 
Cappellaro (INAF OAPd), S. Covino, P. D'Avanzo (INAF-OABr), V. D'Elia 
(INAF-ASDC), F. Getman, A. Grado (INAF-OAC), G. Greco (Urbino 
University, INFN Firenze), L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), 
A. Melandri (INAF-OABr), L. Nicastro, E. Palazzi (INAF-IASF Bo), S. 
Piranomonte, L. Pulone (INAF-OAR), A. Rossi (INAF-IASF Bo), G. Stratta 
(Urbino University/INFN Firenze), G. Tagliaferri (INAF-OABr), V. Testa 
(INAF-OAR), L. Tomasella, S. Yang (INAF-OAPd), E. Brocato (INAF-OAR), on 
behalf of the GRAvitational Wave Inaf TeAm (GRAWITA), report:

We observed the location of "Source 23" (Evans et al., LVC Circ. GCN 
20841
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 ) within the error uncertainty of the LIGO/Virgo event G275697 (LVC 
Circ. 20763), using the Nordic Optical Telescope (NOT) equipped with the 
ALFOSC imaging camera. Observations were carried out at high air mass 
(average 2.1) around twilight using the SDSS i filter. The mean epoch of 
the observation is March 10.26458 UT (10.47 days after the GW event). 
Two images with 2 min exposure and and eight with 1 min were secured (12 
min in total) in the SDSS i filter.

The location of XRT Source 23 lies close to an unrelated bright star (R 
~ 11), which complicates the analysis inside the XRT error circle. Two 
objects, both visible in the Pan-STARRS archival images, are detected 
consistent with the XRT error circle. Their properties are summarized below:

O1:
RA(J2000) = 21:33:15.28
Dec(J2000) = +39:41:11.6
i = 19.76 +- 0.08 AB (NOT data)
i = 19.90 +- 0.15 AB (Pan-STARRS data)

O2:
RA(J2000) = 21:33:14.74
Dec(J2000) = +39:41:07.6
i = 21.94 +- 0.16 AB (NOT data)
i = 21.90 +- 0.15 AB (Pan-STARRS data)

Photometry was computed against nearby stars from the Pan-STARRS 
catalog. For the Pan-STARRS images, we re-measured the photometry to 
properly account for the glare of the bright star, so the quoted values 
differ from those reported in the Pan-STARRS catalog. These values are 
very sensitive to the choice of the background area, hence the large 
uncertainties.

Neither object shows significant variability.

No other objects are detected within the XRT error area, down to a 
3-sigma limiting magnitude i = 21.5 (AB).

D. Kocevski (NASA/MSFC), N.Omodei (Stanford), and G. Vianello (Stanford) 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 G277583.

The Fermi gamma-ray space telescope was passing through the South Atlantic Anomaly (SAA) at the time of the trigger (T0 =  2017-03-13 22:40:10.590| 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 + 388 s.  At that time the instantaneous coverage of the LIGO map was 25%, and reached 100% cumulative coverage within ~7 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 + 388 s  to T0 + 10 ks, and no new sources were significantly detected.  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 100 GeV for this search vary between  3e-10 ��� 3e-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.

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 59 galaxies within the LVC error region for the GW trigger G275697 using the 'bayestar' GW localization map from 2017-2-27 to 2017-3-7 and the observation of 114 galaxies from 2017-3-7 to 2017-3-12 after the update of LALInference localization map. We selected galaxies from the GWGC catalogue within 80.0% of the trigger error region, within a distance of 40.0 Mpc, brighter than -17.5 mag and at a Declination < 20 degree and those galaxies selected have been observed using the Prompt 5 telescope and are part of the ongoing DLT40 search. The first 59 galaxies represent the 4.3% of all galaxies within 40.0 Mpc in the Glade catalogue within the LVC error region for the GW trigger and contains 13.1% of all B band luminosity of those galaxies. After updating our observing schedule, the 114 galaxies represent the 7.4% of all galaxies and contains 27.5% of all B band luminosity. No interesting transients have been identified down to a limit magnitude of 19.0.

Below follow the list of galaxies observed:
Name RA(J2000) DEC(J2000) Dist(Mpc) BMAG KMAG OBS_WINDOW(JD)
ESO176-006 224.29 -54.39 38.01 -21.5 -24.4 2457812.34-2457825.39
NGC4696 192.20 -41.31 35.48 -21.4 -25.6 2457812.34-2457825.39
NGC4603 190.23 -40.97 33.11 -21.2 -24.2 2457812.34-2457825.39
NGC5266 205.75 -48.16 38.02 -21.1 -25.4 2457820.41-2457825.39
NGC3706 172.43 -36.39 38.02 -21.0 -24.9 2457820.41-2457825.39
NGC5156 202.18 -48.91 36.98 -20.9 -24.1 2457820.41-2457825.39
ESO320-026 177.45 -38.78 38.02 -20.9 -24.2 2457820.41-2457825.39
NGC4976 197.15 -49.50 17.3 -20.9 -24.3 2457820.41-2457825.39
IC2977 178.81 -37.69 39.01 -20.8 -23.8 2457820.41-2457825.39
NGC3749 173.97 -37.99 38.02 -20.8 -24.1 2457820.41-2457825.39
NGC3585 168.32 -26.75 20.05 -20.7 -24.8 2457812.34-2457825.39
NGC5266A 205.15 -48.34 38.02 -20.7 -22.2 2457820.41-2457825.39
NGC4444 187.15 -43.26 36.98 -20.6 -23.4 2457820.41-2457825.39
NGC4373A 186.40 -39.31 37.33 -20.6 -24.0 2457812.34-2457825.39
ESO269-057 197.51 -46.43 36.98 -20.6 -24.0 2457820.41-2457825.39
PGC054411 228.64 -52.98 19.36 -20.6 -24.2 2457812.34-2457825.39
NGC3742 173.88 -37.95 38.61 -20.5 -24.2 2457820.41-2457825.39
NGC4112 181.78 -40.20 34.67 -20.5 -23.4 2457820.41-2457825.39
ESO437-030 159.81 -30.29 39.81 -20.5 -23.6 2457812.34-2457825.39
ESO221-010 207.73 -49.05 38.02 -20.5 -23.6 2457820.41-2457825.39
NGC4219 184.11 -43.32 20.99 -20.5 -23.5 2457820.41-2457825.39
IC3896 194.18 -50.34 27.67 -20.5 -24.4 2457820.41-2457825.39
NGC3783 174.75 -37.73 38.02 -20.5 -24.2 2457820.41-2457825.39
ESO320-031 178.52 -39.86 38.18 -20.4 -24.8 2457820.41-2457825.39
NGC5219 204.67 -45.85 36.98 -20.4 -22.8 2457812.34-2457825.39
NGC2992 146.42 -14.32 28.84 -20.3 -23.7 2457812.34-2457825.39
NGC3533 166.78 -37.17 36.88 -20.3 -23.5 2457812.34-2457825.39
ESO175-005 214.44 -52.83 37.36 -20.3 -20.2 2457820.41-2457825.39
IC3370 186.90 -39.33 26.79 -20.3 -24.2 2457812.34-2457825.39
ESO377-010 166.63 -37.65 36.98 -20.3 -23.8 2457812.34-2457825.39
PGC046029 198.58 -46.12 36.98 -20.3 -24.3 2457820.41-2457825.39
ESO321-025 185.42 -39.76 29.38 -20.3 -22.5 2457812.34-2457825.39
ESO221-014 208.02 -48.17 35.81 -20.2 -23.1 2457820.41-2457825.39
ESO221-025 211.89 -48.39 38.93 -20.2 -19.4 2457812.34-2457825.39
ESO320-030 178.29 -39.13 38.02 -20.2 -23.6 2457820.41-2457825.39
NGC2967 145.51 0.3365 29.92 -20.2 -23.4 2457820.41-2457825.39
ESO377-024 168.13 -36.42 38.21 -20.2 -22.9 2457820.41-2457825.39
NGC4835 194.53 -46.26 20.14 -20.2 -23.3 2457820.41-2457825.39
NGC2775 137.58 7.0379 17.3 -20.1 -24.1 2457812.34-2457825.39
ESO437-014 159.22 -32.34 37.33 -20.1 -23.6 2457812.34-2457825.39
ESO221-020 209.59 -48.47 38.29 -20.1 -23.6 2457820.41-2457825.39
ESO321-016 183.86 -38.14 38.02 -20.1 -21.9 2457812.34-2457825.39
ESO221-026 212.09 -47.97 20.31 -20.1 -23.9 2457812.34-2457825.39
NGC3115 151.30 -7.718 10.33 -20.1 -24.1 2457820.41-2457825.39
ESO221-012 207.88 -48.08 38.02 -20.1 -21.9 2457820.41-2457825.39
NGC3564 167.65 -37.54 36.98 -20.0 -23.8 2457812.34-2457825.39
NGC4645 191.04 -41.74 29.92 -20.0 -23.9 2457812.34-2457825.39
ESO321-021 185.06 -40.39 39.65 -20.0 -22.6 2457820.41-2457825.39
PGC028308 147.55 -12.05 38.02 -20.0 -22.5 2457812.34-2457825.39
NGC3557B 167.38 -37.34 36.98 -20.0 -23.7 2457812.34-2457825.39
PGC049119 207.61 -48.27 38.02 -20.0 -22.4 2457820.41-2457825.39
PGC027810 145.82 -9.945 38.39 -20.0 -22.2 2457812.34-2457825.39
ESO322-027 188.67 -40.30 39.54 -20.0 -23.2 2457812.34-2457825.39
NGC3606 169.06 -33.82 37.68 -20.0 -23.4 2457820.41-2457825.39
NGC2974 145.63 -3.698 21.48 -20.0 -25.4 2457820.41-2457825.39
IC3896A 193.87 -50.07 27.67 -20.0 -20.3 2457820.41-2457825.39
NGC3203 154.89 -26.69 32.36 -19.9 -23.6 2457812.34-2457825.39
ESO322-045 190.00 -42.04 38.93 -19.9 -23.0 2457812.34-2457825.39
ESO269-090 200.21 -47.21 37.03 -19.9 -23.3 2457820.41-2457825.39
ESO270-006 200.49 -45.93 36.98 -19.9 -22.5 2457812.34-2457825.39
NGC3717 172.88 -30.30 16.9 -19.9 -23.6 2457812.34-2457825.39
ESO320-027 177.60 -38.64 37.64 -19.9 -20.4 2457820.41-2457825.39
ESO378-020 176.81 -37.54 39.46 -19.9 -23.4 2457820.41-2457825.39
NGC3903 177.26 -37.51 38.02 -19.8 -22.6 2457820.41-2457825.39
ESO221-032 213.03 -49.38 36.98 -19.8 -23.8 2457820.41-2457825.39
NGC3573 167.82 -36.87 37.18 -19.8 -24.0 2457820.41-2457825.39
NGC4575 189.46 -40.53 29.11 -19.8 -22.9 2457812.34-2457825.39
ESO321-018 183.97 -38.09 38.65 -19.7 -19.5 2457812.34-2457825.39
ESO321-019 184.26 -39.05 37.64 -19.7 -22.8 2457812.34-2457825.39
ESO220-023 204.32 -49.74 38.02 -19.7 -23.2 2457820.41-2457825.39
ESO321-005 181.44 -38.85 36.46 -19.7 -22.1 2457820.41-2457825.39
ESO377-029 168.66 -33.90 38.56 -19.7 -23.4 2457820.41-2457825.39
PGC166343 219.26 -54.04 38.04 -19.7 -21.2 2457812.34-2457825.39
IC2580 157.07 -31.51 36.98 -19.7 -22.7 2457812.34-2457825.39
ESO219-022 195.59 -49.47 23.56 -19.6 -21.9 2457820.41-2457825.39
ESO319-016 170.53 -38.06 38.22 -19.6 -20.9 2457820.41-2457825.39
NGC4751 193.21 -42.66 26.19 -19.6 -23.8 2457812.34-2457825.39
ESO376-009 160.50 -33.24 38.78 -19.6 -23.4 2457812.34-2457825.39
ESO321-010 182.92 -38.54 38.02 -19.6 -22.7 2457812.34-2457825.39
NGC3511 165.84 -23.08 12.25 -19.6 -22.3 2457812.34-2457825.39
NGC4573 189.43 -43.62 37.42 -19.6 -23.2 2457820.41-2457825.39
NGC3208 154.92 -25.81 36.98 -19.6 -23.4 2457812.34-2457825.39
IC2627 167.47 -23.72 24.21 -19.6 -22.9 2457812.34-2457825.39
ESO322-042 189.67 -42.21 34.83 -19.6 -21.4 2457812.34-2457825.39
NGC4603C 190.17 -40.76 38.83 -19.6 -23.1 2457812.34-2457825.39
ESO175-009 217.99 -55.46 39.26 -19.6 -24.0 2457812.34-2457825.39
PGC166337 216.64 -52.73 38.39 -19.5 -22.2 2457820.41-2457825.39
ESO320-024 177.35 -38.82 38.89 -19.5 -21.8 2457820.41-2457825.39
NGC2979 145.78 -10.38 38.02 -19.5 -23.3 2457812.34-2457825.39
ESO378-012 174.26 -36.81 37.94 -19.5 -22.6 2457820.41-2457825.39
ESO221-003 207.44 -48.75 38.02 -19.4 -21.9 2457820.41-2457825.39
NGC2993 146.45 -14.36 28.84 -19.4 -22.1 2457812.34-2457825.39
ESO269-085 199.99 -47.28 28.31 -19.4 -23.2 2457820.41-2457825.39
ESO320-004 173.68 -38.25 38.02 -19.4 -21.3 2457820.41-2457825.39
ESO377-021 167.73 -35.98 32.81 -19.4 -22.1 2457820.41-2457825.39
NGC4603A 189.90 -40.73 30.34 -19.4 -22.3 2457812.34-2457825.39
ESO220-009 201.72 -48.16 37.46 -19.4 -22.6 2457820.41-2457825.39
ESO377-019 167.68 -35.35 37.4 -19.4 -21.7 2457820.41-2457825.39
ESO222-015 221.11 -49.40 29.92 -19.4 -18.9 2457812.34-2457825.39
ESO220-026 204.94 -48.29 38.75 -19.4 -19.7 2457820.41-2457825.39
ESO221-004 207.46 -48.57 37.96 -19.4 -19.6 2457820.41-2457825.39
ESO437-033 159.99 -30.19 36.98 -19.3 -22.9 2457812.34-2457825.39
NGC3175 153.67 -28.87 13.87 -19.3 -22.9 2457812.34-2457825.39
ESO322-020 187.30 -40.69 39.58 -19.3 -20.4 2457812.34-2457825.39
ESO438-005 167.24 -28.37 26.18 -19.3 -19.6 2457820.41-2457825.39
NGC2947 144.02 -12.43 39.88 -19.3 -23.0 2457812.34-2457825.39
ESO268-027 189.62 -42.86 38.42 -19.3 -22.4 2457820.41-2457825.39
ESO267-016 181.59 -44.44 39.26 -19.3 -22.3 2457820.41-2457825.39
ESO268-044 192.17 -45.00 37.67 -19.3 -22.2 2457820.41-2457825.39
ESO569-014 162.85 -19.89 24.77 -19.3 -20.9 2457812.34-2457825.39
ESO221-022 210.04 -48.26 34.2 -19.3 -22.5 2457812.34-2457825.39
NGC5333 208.60 -48.51 35.81 -19.2 -24.4 2457812.34-2457825.39
ESO269-060 197.74 -46.22 36.98 -19.2 -22.7 2457812.34-2457825.39
ESO269-078 199.15 -45.89 37.86 -19.2 -20.2 2457812.34-2457825.39

P.A. Evans (U. Leicester), J.A. Kennea (PSU), S.D. Barthelmy
(NASA/GSFC), A.P. Beardmore (U. Leicester), A.A. Breeveld (UCL-MSSL),
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. Giommi (ASI), C. Gronwall (PSU), H.A. Krimm
(CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), D.
Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),
B. Mingo (U. Leicester),  J.A. Nousek (PSU), S.R. Oates (U. Warwick),
P.T. O'Brien (U. Leicester), J.P. Osborne (U. Leicester), C. Pagani (U.
Leicester), K.L. Page (U.Leicester), D.M. Palmer (LANL), 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:

As discussed in LVC Circular 20841, Swift is conducting further
observations of the 'rank 3' X-ray sources detected in our initial search
of the LIGO/VIRGO error region. These are uncatalogued X-ray sources which
are below existing catalogue limits and therefore cannot be distinguished
as new or pre-existing sources.

Previously, Source 23 (Evans et al, LVC Circ. 20812, 20841) appeared to be
fading with a significance of 3.5 sigma. Swift subsequently performed a
series of daily observations, between 2017-03-13 and 2017-03-16, which
have shown that the source flux is remaining approximately constant, so is
unlikely to be related to the GW event and is therefore no longer
considered a source of interest.

In addition, sources 30, 88, 100 and 108 also show no signs of
variability. Source 89 matches a catalogued object which appears to be a
flare star, so the X-ray detection was most likely simply a stellar flare.
Observations of the other 'rank 3' sources are ongoing.

This circular is an official product of the Swift-XRT team.

K. P. Mooley (Hintze Fellow, Oxford) reports on behalf of a larger 
collaboration

We observed 52 galaxies from the GLADE catalog (weighted by the B-band 
luminosities) and 8 galaxies from the CLU catalog (stellar mass-weighted 
from Cook et al., LVC GCN 20800
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 ) within the BAYESTAR error region for 
the neutron star merger candidate G275697 (Siellez et al. LVC GCN 
20763
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 ). A plot of the galaxy selection function and the list of targeted 
galaxies can be found here: 
https://www.dropbox.com/s/mho6k0cm01jaqqm/G275697_AMILA_LVC.pdf?dl=0. 
The observations, designed to detect a possible orphan afterglow, were 
carried out with the AMI Large Array (AMI-LA) at 15 GHz over two epochs 
within 15 days post-trigger. The median 4sigma detection threshold in 
each epoch is 200 uJy at the pointing center (400 uJy at the half power 
radius of the beam, 3 arcmin). We manually inspected all the sources 
detected above 4sigma within approximately 4 arcmin (= 230 kpc 
separation at 200 Mpc) of the AMI-LA beam, amounting to a total search 
area of 0.8 sq. deg and a containment volume probability of 1.3%.

We have devised a ranking scheme (rank 1-4; with 1 being the most likely 
to be associated with the GW event and 4 being the least likely) for 
transient candidates similar to that of Swift. A detailed description of 
the ranking scheme can be found in the URL mentioned above. Among the 
~70 unique point sources detected in the AMI-LA observations, we found 
two candidates which warrant further follow up. The candidates are 
detailed below. All quoted upper limits are 3sigma. We note that the 
observations for a third epoch with the AMI-LA are ongoing, and further 
information on these and other candidates will be reported in subsequent 
GCNs.

Rank 2:
======
1) AMILA J220556+503620
March 02.38 (UT): <312 uJy
March 09.36 (UT): 620+/-75 uJy
Comments: All sources in the field are ~10% smaller than the synthesized 
beam. Nearby source is stable.

Rank 3:
======
1) AMILA J213542+394253
March 03.59 (UT): 1257+/-78 uJy
March 10.57 (UT): 1621+/-83 uJy
Comments: Variable (>3sigma). No nearby source for flux density comparison.

We thank the AMI staff for scheduling these observations.

J.W. Broderick (ASTRON), A. Rowlinson (UvA, ASTRON), A.J. Stewart
(Oxford), P.G. Jonker (SRON, RU), R.P. Fender (Oxford),
R.A.M.J. Wijers (UvA), B.W. Stappers (Manchester), S. ter Veen
(ASTRON), S. Ghosh (RU), A. Shulevski (ASTRON) report on behalf of the
LOFAR Transients Key Science project

From 2017 March 16-20, we observed a large fraction of the
localization error range of the Advanced LIGO trigger G275697 with the
ILT (International Low-Frequency Array [LOFAR] Telescope). The
observations were obtained with the high-band antennas (HBA) at a
centre frequency of 145 MHz (bandwidth 15.8 MHz). We used 6
simultaneous beams on the sky, where each beam has a field of view of
approximately 12 deg^2 (beam FWHM 3.9 deg). The observations cover
roughly 300 deg^2 in total at optimum sensitivity. Each field was
observed for a total of up to 225 min using a number of separate 25
min snapshots.

The beam centres are given below (RA & Dec in degrees); analysis is
ongoing.

Pointing 1
(integration time 225 min over the period 2017-03-16 06:11-13:32 UTC)

1) 325.025000    41.804167
2) 326.746137    44.268755
3) 321.301114    41.682969
4) 323.022251    44.147557
5) 327.027749    39.460777
6) 328.748886    41.925365

Pointing 2
(integration time 225 min over the period 2017-03-16 06:37-13:58 UTC)

1) 328.920158    46.542342
2) 331.030859    48.911430
3) 324.881912    46.615076
4) 326.992613    48.984164
5) 330.847703    44.100521
6) 332.958404    46.469609

Pointing 3
(integration time 225 min over the period 2017-03-17 06:11-13:32 UTC)

1) 319.219737    31.633699
2) 320.468591    34.200728
3) 315.984241    31.271028
4) 317.233096    33.838057
5) 321.206377    29.429341
6) 322.455232    31.996370

Pointing 4
(integration time 225 min over the period 2017-03-17 06:37-13:58 UTC)

1) 321.874437    36.767756
2) 323.340302    39.285962
3) 318.419103    36.525591
4) 319.884968    39.043797
5) 323.863905    34.491716
6) 325.329771    37.009921

Pointing 5
(integration time 200 min over the period 2017-03-18 05:11-12:32 UTC)

1) 314.137598    21.441764
2) 315.303983    23.999416
3) 311.174714    21.103147
4) 312.341099    23.660799
5) 315.934097    19.222730
6) 317.100481    21.780382

Pointing 6
(integration time 200 min over the period 2017-03-18 05:37-12:58 UTC)

1) 316.565036    26.557069
2) 317.828472    29.095384
3) 313.475776    26.266633
4) 314.739212    28.804948
5) 318.390860    24.309189
6) 319.654296    26.847504

Pointing 7
(integration time 175 min over the period 2017-03-20 09:55-15:32 UTC)

1) 333.611809    51.066434
2) 336.179366    53.328480
3) 329.210699    51.332745
4) 331.778257    53.594791
5) 335.445360    48.538078
6) 338.012918    50.800124

Pointing 8
(integration time 200 min over the period 2017-03-20 09:29-15:58 UTC)

1) 8.225000    67.934722
2) 15.175293   68.885036
3) 2.559069    69.720728
4) 9.509362    70.671042
5) 6.940638    65.198402
6) 13.890931   66.148716

The LIGO Scientific Collaboration and Virgo report:

We report an update on the significance of the gravitational-wave trigger
G275697 (GCN 20763
Loading...
 
 ) . This trigger was reported by the online PyCBC search
with a false alarm rate (FAR) of 4.5 per year; i.e. background noise in the
detectors produces 4.5 triggers per year as loud as G275697 in the PyCBC
low-latency search. This trigger had low significance, but passed the FAR
threshold of ~ 1 / month for generating an alert.

We have completed the offline search over the time containing G275697 using
the PyCBC (Usman et al. 2016, CQG 33, 215004) and GstLAL (Messick et al.
2016, PRD 95, 042001) searches. These offline analyses provide the final
significance for candidate events.

Neither search produced a significant trigger at the time of G275697. We
conclude that G275697 is not a trigger of interest and does not warrant
further follow-up.

A. Rowlinson (UvA, ASTRON), J.W. Broderick (ASTRON), A.J. Stewart
(Oxford), P.G. Jonker (SRON, RU), R.P. Fender (Oxford),
R.A.M.J. Wijers (UvA), B.W. Stappers (Manchester), S. ter Veen
(ASTRON), S. Nissanke (RU), A. Shulevski (ASTRON) report on behalf
of the LOFAR Transients Key Science project

From 2017 May 29 - June 2, we observed a large fraction of the
localization error range of the Advanced LIGO trigger G275697 with the
ILT (International Low-Frequency Array [LOFAR] Telescope). The
observations were obtained with the high-band antennas (HBA) at a
centre frequency of 145 MHz (bandwidth 15.8 MHz). We used 6
simultaneous beams on the sky, where each beam has a field of view of
approximately 12 deg^2 (beam FWHM 3.9 deg). The observations cover
roughly 300 deg^2 in total at optimum sensitivity. Each field was
observed for a total of up to 225 min using a number of separate 25
min snapshots.

The beam centres are given below (RA & Dec in degrees); analysis is
ongoing.

Pointing 1
(integration time 225 min over the period 2017-05-29 01:11-08:32 UTC)

1) 333.611809    51.066434
2) 336.179366    53.328480
3) 329.210699    51.332745
4) 331.778257    53.594791
5) 335.445360    48.538078
6) 338.012918    50.800124

Pointing 2
(integration time 225 min over the period 2017-05-29 01:37-08:58 UTC)

1) 8.225000    67.934722
2) 15.175293   68.885036
3) 2.559069    69.720728
4) 9.509362    70.671042
5) 6.940638    65.198402
6) 13.890931   66.148716

Pointing 3
(integration time 225 min over the period 2017-05-30 01:11-08:32 UTC)

1) 325.025000    41.804167
2) 326.746137    44.268755
3) 321.301114    41.682969
4) 323.022251    44.147557
5) 327.027749    39.460777
6) 328.748886    41.925365

Pointing 4
(integration time 225 min over the period 2017-05-30 01:37-08:58 UTC)

1) 328.920158    46.542342
2) 331.030859    48.911430
3) 324.881912    46.615076
4) 326.992613    48.984164
5) 330.847703    44.100521
6) 332.958404    46.469609

Pointing 5
(integration time 225 min over the period 2017-06-01 00:11-07:32 UTC)

1) 319.219737    31.633699
2) 320.468591    34.200728
3) 315.984241    31.271028
4) 317.233096    33.838057
5) 321.206377    29.429341
6) 322.455232    31.996370

Pointing 6
(integration time 225 min over the period 2017-06-01 00:37-07:58 UTC)

1) 321.874437    36.767756
2) 323.340302    39.285962
3) 318.419103    36.525591
4) 319.884968    39.043797
5) 323.863905    34.491716
6) 325.329771    37.009921

Pointing 7
(integration time 225 min over the period 2017-06-02 00:11-07:32 UTC)

1) 314.137598    21.441764
2) 315.303983    23.999416
3) 311.174714    21.103147
4) 312.341099    23.660799
5) 315.934097    19.222730
6) 317.100481    21.780382

Pointing 8
(integration time 225 min over the period 2017-06-02 00:37-07:58 UTC)

1) 316.565036    26.557069
2) 317.828472    29.095384
3) 313.475776    26.266633
4) 314.739212    28.804948
5) 318.390860    24.309189
6) 319.654296    26.847504