LIGO/Virgo G299232

The LIGO Scientific Collaboration and Virgo report:


The MBTA CBC analysis (Adams et al. CQG 33, 175012, 2016) identified
candidate G299232 during real-time processing of data from LIGO
Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at
2017-08-25 13:13:31 UTC (GPS time: 1187702035.9831). Data from Virgo
(V1) were included in a followup analysis using the PyCBC toolkit
(Nitz, et al. 2017, arXiv:1705.01513
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 ) and used to generate the
localization given below.

G299232 is a low-significance CBC candidate with a false alarm rate,
As determined by the online analysis, of 1.68e-07 Hz, or about 5.3 per
year, just within our threshold of 6 per year for announcing
candidates. The event's properties can be found at this URL:

https://gracedb.ligo.org/events/view/G299232

If the candidate is astrophysical in origin, it appears consistent
with the merger of a black hole and a neutron star. For more details
on the source classification, please consult this technical document:

https://dcc.ligo.org/T1600571/public/main<https://owa.exchange.mit.edu/owa/redir.aspx?C=08JG3EzySZbccUYOg_q0nFAJYtskviWom-7tvEUl40pBz1r9vuvUCA..&URL=https%3a%2f%2fdcc.ligo.org%2fT1600571%2fpublic%2fmain>

A rapid localization with distance information generated by the
BAYESTAR pipeline (Singer et al. 2016, ApJL 829, 15) including
information from H1, L1, and V1 is available and can be retrieved from
the GraceDB event page: bayestar-HLV.fits.gz.

The 50% credible region spans about 450 deg2 and the 90% region about
2040 deg2. The probability is concentrated in a pair of long, thin
arcs that spread across both the northern and southern hemispheres,
although the probability is concentrated in the northern
hemisphere. Marginalized over the whole sky, the a posteriori
luminosity distance estimate is 339 +/-110 Mpc.

Updates on our analysis of this event, including updated localizations
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

The analysis FOUND A COINCIDENT ONLINE TRACK-LIKE NEUTRINO CANDIDATE detected by IceCube within the 500 second window surrounding LIGO/Virgo event candidate G299232 using the bayestar.fits.gz skymap. The coordinates of the reconstructed neutrino source are below:

#            dt[s]     RA[deg]    Dec[deg]      E[TeV]  Sigma[deg]
------------------------------------------------------------------
1.         -233.82        27.1        45.1        0.39         3.8

In an analysis completed at 2017-08-25 13:47:30 UTC, we searched IceCube online track-like neutrino candidates (GFU) detected in a [-500,500] second interval about the LIGO-Virgo trigger G299232. We compared the candidate source directions of 7 temporally-coincident neutrinos to the BAYESTAR skymap, with the following parameters:

#            dt[s]     RA[deg]    Dec[deg]      E[TeV]  Sigma[deg]
------------------------------------------------------------------
1.         -233.82        28.2        44.8        0.39         3.8
2.         -230.58       286.6         4.9        1.08         0.7
3.         -213.50       104.1        -0.8        1.46         0.3
4.          131.55       285.1        48.7        0.76         0.7
5.          227.96       113.9       -56.6      160.86         0.5
6.          367.52        64.8       -10.6        2.39         0.3
7.          485.21         9.1       -21.5        7.75         0.3


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

A coincident neutrino-GW skymap has been posted to GraceDB (<https://gracedb.ligo.org/apiweb/events/G299232/files/coinc_skymap_initial_icecube.png,0>). A JSON-formatted list of the above neutrinos can be downloaded from GraceDB at: <https://gracedb.ligo.org/apiweb/events/G299232/files/IceCubeNeutrinoList.json,0>

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

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

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 G299232 event
using the Bayestar-HLV probability map at event time. The ANTARES 
visibility at the time of the alert together with the 50% and 90% contours
of the probability map are shown in: 
https://www.cppm.in2p3.fr/~dornic/events/G299232/250817_visibility2.png 
<https://www.cppm.in2p3.fr/%7Edornic/events/G298389/gw190817_visi.png> 
(gwantares/GW@ANT51). Considering the location probability provided by 
the LIGO collaboration, there is a 42% chance that the GW emitter was in 
the ANTARES field of view.

No up-going muon neutrino candidate events were recorded in the ANTARES 
sky during a +/- 500s time-window centered on the G299232 event
time. The expected number of atmospheric background events in the region 
visible by ANTARES is ~1.1e-2 in the +/- 500s time window. An
extended search during +/- 1 hour gives no up-going neutrino coincidence.

The results of the second analysis covering the full sky as well as an 
estimate of the upper limit on the associated neutrino fluence will be 
sent in a subsequent circular.

ANTARES, being installed in the Mediterranean Deep Sea, is the largest 
neutrino detector in the Northern Hemisphere. It is primarily
sensitive to astrophysical neutrinos in the TeV-PeV energy range.  At 10 
TeV, the median angular resolution for muon neutrinos is below 0.5 degrees.
In the range 1-100 TeV, ANTARES has the best sensitivity to a large 
fraction of the Southern sky.

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

In GCN 21694
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  we reported the identification of an IceCube neutrino candidate that is temporally (within [-500s,500s]) and directionally (within 90% CL) coincident with LIGO/Virgo G298048.

We reran our analysis using the updated three-detector skymap, bayestar-HLV.fits.gz. The same neutrino candidate is still COINCIDENT with the updated map. The properties of the neutrino candidate are below:


#            dt[s]     RA[deg]    Dec[deg]      E[TeV]  Sigma[deg]
------------------------------------------------------------------
1.         -233.82        28.2        44.8        0.39         3.8

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

A coincident neutrino-GW skymap has been posted to GraceDB (<https://gracedb.ligo.org/apiweb/events/G299232/files/coinc_skymap_initial_icecube.png,1>). A JSON-formatted list of the neutrinos used can be downloaded from GraceDB at: <https://gracedb.ligo.org/apiweb/events/G299232/files/IceCubeNeutrinoList.json,1>

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 (IRAP, France)
R. Sunyaev (IKI, Russia) P. Ubertini (IAPS-Roma, Italy)

We investigated serendipitous INTEGRAL observations carried out at the
time of the LIGO/Virgo GW event candidate G299232.  The satellite was
pointing at RA=262.993 Dec=-27.052, near the lower-probability arc of
LIGO/Virgo localization. About 10% of LIGO localization probability
was in IBIS and SPI FoV. Depending on the location within LIGO 90%
confidence region the best upper limit is set by the anti-coincidence
shield of the spectrometer on board of INTEGRAL (SPI/ACS), IBIS/ISGRI,
or IBIS/PICsIT. A fraction of the localization of G299232 is not
optimal for SPI-ACS observation.

The INTEGRAL IBAS automatically inspects both ISGRI Field of View and
all-sky SPI-ACS light curve. It did not reveal any significant excess
above the background.

We investigated the SPI-ACS, IBIS/PICsIT, and IBIS/ISGRI light curves
between -500 and +500 s from the trigger time (2017-08-25 13:13:37
UTC) on temporal scales from 0.1 to 100 s, and found no evidence for
any significant deviation from the background.  We estimate a median
3-sigma upper limits in 90% LIGO localization region of 1.0e-6 erg/cm2
(75-2000 keV) assuming a duration of 8s and Band model parameters
alpha=-1, beta=-2.5, and E_ peak = 300 keV.  To derive a limit for a
typical short burst with 1 s duration, we use a harder cutoff power
law spectrum with a photon index of -0.5 and an Epeak = 500 keV. We
find a median limiting fluence of 3.6e-7 erg/cm2 (75-2000 keV) at 3
sigma c.l.

For the fraction of LIGO/Virgo localization probability within the Field of
View of INTEGRAL pointing instruments (IBIS, JEM-X, and SPI), the
combination of these instruments allows to set stringent upper
limit in a broad energy range from 3 keV to 8 MeV (Savchenko et al
2017 A&A...603A..46S).  Further analysis of these data is ongoing.

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

In response to the LIGO/Virgo GW event G299232 (T0=2017-08-25 13:13:37.983 UT;
GCN #21693
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 ), we performed a preliminary AGILE Mini-CALorimeter (MCAL) data
analysis on the time interval T0 -/+100s.

In the nearest data acquisition starting at T1=T0+45s we detected a short
burst occurring about at T0+47s which triggered both the on-board 16 ms and
64 ms timescale hardware logics.
The MCAL light curve shows a sharp single peak that lasted about 1 sec
and has a total number of ~1333 counts above 400 keV in the detector,
above an average background rate of 614 counts/s.

Additional analysis of AGILE MCAL data is in progress, to further verify
possible spurious contaminations of this detection.
The AGILE-MCAL detector has a full solid angle acceptance, and is
operational in the range 0.4 - 100 MeV. The MCAL current trigger rate is
on average ~ 0.15 every 20 sec.

G. Piano, M. Cardillo (INAF/IAPS), F. Verrecchia (SSDC and INAF/OAR), M.
Pilia (INAF/OA-Cagliari), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata),
A. Bulgarelli (INAF/IASF-Bo), C. Pittori (SSDC and INAF/OAR), I. Donnarumma
(ASI), F. Longo (Univ. Trieste and INFN Trieste), A. Ursi, G. Minervini, A.
Argan, Y. Evangelista (INAF/IAPS), F. Lucarelli (ASDC and INAF/OAR),  N.
Parmiggiani, A. Zoli, V. Fioretti, F. Fuschino (INAF/IASF-Bo), A. Trois
(INAF/OA-Cagliari) M. Marisaldi (INAF/IASF-Bo and Bergen University),  A.
Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team:
In response to the LIGO/Virgo GW trigger event G299232 at T0 = 2017-08-25
13:13:37.983 UTC (GCN #21693
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 ), we performed an analysis of the AGILE
Gamma-Ray Imaging Detector (GRID) data on different  timescales. On LIGO/Virgo
trigger time (T0) the GRID exposure covered nearly 42% of the LIGO/Virgo
localization region (at 90% confidence level; LR), observed at off-axis
angles between 20 and 55 deg.

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

from 1.5e-06 to 7.8e-06 erg cm^-2 s^-1 for integration time of 2s
from 1.5e-07 to 7.8e-07 erg cm^-2 s^-1 for integration time of 20s
from 3.9e-08 to 2.2e-07 erg cm^-2 s^-1 for integration time of 100s

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

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

We report the search results in the BAT data within T0 +/- 100 s of the
LVC event G299232 (LIGO/VIRGO Collaboration GCN Circ. 21693
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 ), 
where T0 is the LVC trigger time (2017-08-25T13:13:31 UTC).

The center of the BAT FOV at T0 is
RA = 253.402 deg,
DEC = 39.751 deg,
ROLL = 288.107 deg.
The BAT Field of View (>10% partial coding) covers 11.56% of the integrated
LVC localization probability.

Within T0 +/- 100 s, no significant detections (signal-to-noise ratio >~ 5 sigma) 
are found in the BAT raw light curves with time bins of 64 ms, 1 s, and 1.6 s, 
respectively. The short spike appears at ~T-93 s in the 64-ms and 1-s light curve 
is consistent with a glitch caused by detector noise, because it is only seen in 
one single time bin and in the 15-25 keV band, and no significant detection in 
the image domain. Assuming an on-axis (100% coded) short GRB with a typical spectrum 
in the BAT energy range (i.e., a simple power-law model with a power-law index of -1.32, 
Lien & Sakamoto et al. 2016), the 5-sigma upper limit in the 1-s binned light curve 
corresponds to a flux upper limit (15-350 keV) of ~ 1.22 x 10^-7 erg/s/cm^2.

BAT retains decreased, but significant, sensitivity to rate increases for
gamma-ray events outside of its FOV. About 27.56% of the integrated LVC
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.

David O. Cook (Caltech), Angela Van Sistine (UW Milwaukee), Leo Singer
(NASA/GSFC), M. M. Kasliwal (Caltech), and David Kaplan (UW Milwaukee)

report on behalf of the iPTF and GROWTH collaborations

We spatially cross-matched the LIGO/Virgo G299232 trigger (90% containment
volume using bayestar-HLV.fits; LVC GCN 21693
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 ) with our Census of the Local
Universe (CLU; Cook et al. in prep) galaxy catalog and found 17,593
galaxies. This catalog is a compilation of galaxies with existing redshifts
from many sources (e.g., NED, SDSS, etc) and new galaxies from a 3PI
four-filter narrow-band survey to look for redshifted Halpha emission out
to 200 Mpc with the Palomar Oschin 48-inch telescope. Currently, the
narrow-band survey is only calibrated inside the footprint of SDSS. Of the
17,593 galaxies in the error volume, 17,120 come from a compilation of
known galaxies and 473 are new, emission-line CLU galaxy candidates derived
from our Halpha survey.

We list here the top 20 galaxies sorted by stellar mass (Mstar) for
galaxies whose location on the sky and distance falls in the 90% volume
reported by the BAYESTAR probability sky map (Singer et al. 2016). We also
list the dust-corrected star formation rates (SFRs) for galaxies with GALEX
FUV detections and a 'nan' for those with no detection.



                 name_NED                    ra      dec    distmpc
logsfr_fuv logmstar     P
----------------------------------------- -------- -------- -------
---------- --------  ---------------
                          [HB89] 0241+622  41.2405  62.4685  191.43
nan    12.05   0.140963304855
                                LDCE 1285 271.5879 -25.4311  103.44
nan    11.91   0.800186835374
                           ESO 344- G 016 333.6750 -38.8064  170.09
1.540    11.72   0.886386086915
                                UGC 00774  18.4626  13.2719  209.58
1.593    11.69   0.528731713093
                                  IC 0260  42.7537  46.9548  123.80
nan    11.54   0.882625900958
                      6dF J1741553-121157 265.4803 -12.1990  152.05
nan    11.44   0.753441530388
                           NGC 0326 NED01  14.5943  26.8662  208.72
-0.405    11.33     0.7901652699
                                 NGC 6958 312.1785 -37.9975   99.86
nan    11.31   0.789778583289
                  2MASX J01571097+4715588  29.2956  47.2666  207.11
nan    11.30   0.281525733779
                                  IC 1695  21.2818   8.6995  210.38
nan    11.30   0.431687269372
                                UGC 01400  29.0184  36.1313   77.62
nan    11.29   0.335875843118
                                 NGC 6099 243.8982  19.4534  207.50
nan    11.28   0.714631039094
                                 MRK 0567  19.8255   4.5781  141.83
1.304    11.26   0.572392023225
                           NGC 6240 NED01 253.2453   2.4010  100.61
nan    11.26   0.752082522541
                 SDSS J005601.73-010352.2  14.0072  -1.0645  189.66
nan    11.26   0.737619298894
                  2MASX J01543532+6437570  28.6470  64.6326  149.45
nan    11.26   0.593543567206
                  2MASX J20145535-3240004 303.7306 -32.6668  409.11
nan    11.24   0.892450247448
                                UGC 00959  21.1875  32.1657  173.33
0.907    11.24   0.422381064489
                 SDSS J162220.44+115214.9 245.5852  11.8708  215.90
nan    11.21   0.636472864491
             GALEXASC J015114.07+223457.6  27.8086  22.5827  133.44
nan    11.20    0.34030312252


The SFRs are derived from GALEX all sky kron FUV magnitudes via the
prescription of Murphy et al. (2011) and have been corrected for internal
dust extinction using a combination of GALEX FUV and 22um ALLWISE fluxes
(Hao et al. 2011). The quoted stellar masses are derived from 3.4um ALLWISE
fluxes and a mass-to-light ratio of 0.5 (McGaugh & Schombert et al. 2015).

D. Kocevski (NASA/Marshal), G. Vianello (Stanford), N. Omodei (Stanford), S. Buson (NASA/GSFC), N. Di Lalla (Univ. Pisa & INFN Pisa), and M. Razzano (Univ. Pisa & INFN Pisa) report on behalf of the Fermi-LAT team: 

We searched data collected by the Fermi Large Area Telescope (LAT) for a possible high-energy (E > 100 MeV) gamma-ray emission in spatial/temporal coincidence with the LIGO/Virgo trigger G299232 (GCN 21693
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 ). 

At the time of the trigger (T0 = 2017-08-25 13:13:37.977 UTC, 525359622.977 MET), 40% of the LIGO/Virgo Bayestar probability map based on L1, H1, and V1 observations was in the LAT field of view, and we reached 100% cumulative coverage within ~5400 s after the trigger. We define "instantaneous coverage" as the integral over the region of the 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 probability 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. 

The Fermi-LAT point of contact for this event is Daniel Kocevski (daniel.kocevski@nasa.gov) 

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.

Arvind Balasubramanian (IISER Pune), Varun Bhalerao (IUCAA), 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 G298048 trigger time, 2017-08-25 13:13:31 UTC, to look for any coincident 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 Bayestar skymap provided by LVC (bayestar-HLV.fits.gz), the sky visible to CZTI has 58.3% probability of containing the EM counterpart.

CZTI data were de-trended to remove orbit-wise background variation. We then searched data from the four independent, identical quadrants to look for coincident spikes in the count rates. Searches were undertaken by binning the data in 0.1s, 1s and 10s respectively. Statistical fluctuations in count rates were estimated by using data from 5 previous orbits. We selected confidence levels such that the probability of a false trigger in this 100s window is 10^-4. We do not find any evidence for any hard X-ray transient in this window. In particular, we do not detect the AGILE MCAL candidate reported by Cardillo et al (GCN 21700
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 ).

We convert our count rates into fluence and flux limits by assuming that the source spectrum has band parameters alpha = -1.0, beta = -2.5, Epeak = 300. The upper limits for source fluence and flux in a 30-200 keV band at different timescales are:

Calculating fluxes assuming band parameters alpha = -1.0, beta = -2.5, Epeak = 300
0.1 s: Effective fluence limit= 3.52e-7 ergs/cm^2; flux= 3.52e-6 ergs/cm^2/s
1.0 s: Effective fluence limit= 7.89e-7 ergs/cm^2; flux= 7.89e-7 ergs/cm^2/s
10.0s: Effective fluence limit= 1.06e-6 ergs/cm^2; flux= 1.06e-7 ergs/cm^2/s

The corresponding all-sky maps are uploaded at https://gracedb.ligo.org/apiweb/events/G299232/files/G299232_CZTI_limits.pdf,0

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.

P. A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:

Our automated analysis of the XRT follow up of G299232 recently reported an apparent Rank 2 source as a GCN Counterpart Notice.

Manual inspection of the images shows that the ���source" lies in a region of extended diffuse emission, likely caused by partial illumatination of the CCD by scattered light from the bright Earth limb. We do not consider this source to be astrophysical in origin. The counterpart notices are preliminary, as they are generated entirely automatically.

This circular is an official product of the Swift team.

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

The CALET Gamma-ray Burst Monitor (CGBM) was operating at the trigger time
of G299232 (The LIGO Scientific Collaboration and Virgo Collaboration,
GCN Circ. 21693
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 ).  No CGBM on-board trigger occurred at the time
of the event.  Based on the LIGO-Virgo localization sky map (bayestar-HLV.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 70% and 72%.

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 G299232.  Similar to CGBM, the northern arc of the high probability area of the
LIGO-Virgo localization map was in the field of view of CAL.  Using CAL data, we have
searched for gamma-ray events in the 10-100 GeV band from -60 sec to +60 sec from
the GW trigger time and found no candidates.  The 90% upper limit of CAL is
2e-4 erg/cm2/s (10-100 GeV) when the summed LIGO-Virgo probabilities reaches at 20%.

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

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

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

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

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


Global MASTER robotic net automatically starting folow-up inspection of 
the bayestar-HLV  map of the G299232/PGWB170825.55* event time (2017-08-25 
13:13:37 UTC, LVC GCM 21693) by 7 robots MASTER telescopes.

Table I. Time starting MASTER-Net follow-up observations.

Site              |  UT start               | T-Ttrig, Ks
------------------|-------------------------|--------
MASTER-SAAO       | 2017-08-25 20:06:39.328 | 24.782
MASTER-Kislovodsk | 2017-08-25 20:09:22.169 | 24.945
MASTER-IAC        | 2017-08-25 20:28:20.207 | 26.083
MASTER-OAFA       | 2017-08-25 23:08:25.365 | 35.688
MASTER-Amur       | 2017-08-26 11:37:19.06  | 80.622
MASTER-Tunka      | 2017-08-26 13:28:02.508 | 87.265


MASTER OTJ033744.97+723159.0 discovery near NGC1343.

MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) 
= 03h 37m 44.97s +72d 31m 59.0s on 2017-08-27.01649 UT.
The OT unfiltered magnitude is 17.0m (limit 18.2m).

The OT is seen in 4 images. There is no minor planet at this place.

We have reference image without OT on 2012-12-17.70730 UT with unfiltered 
magnitude limit 19.4m.

The discovery and reference images 
are available at
http://master.sai.msu.ru/static/OT/033744.97723159.0.png

The MASTER covering map is available at
http://master.sai.msu.ru/static//ligo/db/G299232/151//img/MASTER.G299232.000.12.gif


*PGWB170825.55 - Possible Gravitational Wave Burst 2017 Aug 25.55 UT - 
internal disignation for electromagnetic  people.

This message can be citted.

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

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

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

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

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

Smal edition to GCN LVC GCN 21719
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  .

MASTER OTJ033744.97+723159.0 off set from the center of the NGC1343 are:
21W     137.9S.

The spectroscopic observations are requared.

This message can be citted.

M. Im, C. Choi, G. Lim, J. Kim, H. M. Lee (SNU), M. J. Kim, H. J. Lee
(KASI) on behalf of the KU collaboration

We obtained r, i, and z-band images of MASTER OTJ033744.97+723159.0 near
NGC 1343 (Lipunov et al. GCN 21719
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 , 21720
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 ), a candidate counterpart of
G299232/PGW170826 (Siellez et al. GCN 21693
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 ). The data were taken with
SQUEAN instrument on the McDonald Observatory���s 2.1m telescope at
2017-08-27, 10:57 (UT). Before Galactic extinction correction, it has r =
16.67 +- 0.03 and i = 16.71 +- 0.03 (AB mag), with r-i color of r ���i ~
-0.04 mag. However, after Galactic extinction correction, we get r= 15.89
and i = 16.13 and r-i = -0.24 mag, a rather blue color in comparison to
G298048 shortly after its discovery (Nicholl et al. GCN 21541
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 ).

A. Rowlinson (UvA, ASTRON), J.W. Broderick (ASTRON), 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) and A. Shulevski
(ASTRON) report on behalf of the LOFAR Transients Key Science Project

On 2017 August 25, we conducted a LOFAR follow-up observation of the
Advanced LIGO/Virgo trigger G299232 with the ILT (International
Low-Frequency Array [LOFAR] Telescope). The observation began at
14:47:31 UTC. The observations were obtained with the high-band
antennas (HBA) at a centre frequency of 145 MHz (bandwidth 11.9
MHz). We used 8 simultaneous beams on the sky, where each beam has a
field of view of approximately 12 deg^2 (beam FWHM 3.9 deg at 150
MHz). The observations cover roughly 50 deg^2 in total at optimum
sensitivity. Each field was observed in both imaging and beamformed
modes for a total of 120 min.

The beam centres (RA/Dec), in degrees, are as follows:

1) 27.8625 50.4931
2) 30.6384 50.4931
3) 25.0866 50.4931
4) 29.2505 52.8971
5) 26.4745 52.8971
6) 29.2505 48.0890
7) 26.4745 48.0890
8) 28.6250 57.4389

Analysis is ongoing.

We thank the ASTRON Radio Observatory for rapidly scheduling the
observations.

M. M. Anderson (Caltech) and G. Hallinan (Caltech) on behalf of the OVRO-LWA collaboration.

The OVRO-LWA was observing prior, during and after the detection of LIGO/Virgo G299232, with continuous frequency coverage from 30 MHz to 85 MHz and a field-of-view covering the entire northern hemisphere arc of the 90% localization region (bayestar-HLV.fits.gz, LVC GCN #21693
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 ).  Data reduction and analysis have commenced investigating the possible presence of a low frequency prompt counterpart to the event, focusing on observations spanning 1 hour prior to and 3 hours following the detection of LIGO/Virgo G299232, from 2017-08-25 12:13 UTC to 16:13 UTC.

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

We have observed part of the localization of the LIGO/Virgo candidate 
G299232 during the nights 2017-08-25 from 19h12 UT with TRE (5 fields, 
total 80sq. deg.) and TCA (5 fields, total 18sq.deg.). The position of 
the center of the fields are reported below. Analysis is ongoing.

Site         RA               DEC           Start of the observations (UT)
TCA        02:06:31    40:39:53    2017-08-25T19:43:50.376
TCA        02:03:52    38:48:17    2017-08-25T19:48:10.376
TCA        02:09:21    42:31:29    2017-08-25T19:28:20.376
TCA        02:01:22    36:56:41    2017-08-25T19:56:50.376
TCA        02:12:23    44:23:05    2017-08-25T19:12:50.376
TRE        02:04:08    40:12:00    2017-08-25T21:04:09.792
TRE        02:00:24    36:00:00    2017-08-25T20:28:39.792
TRE        01:53:50    40:12:00    2017-08-25T20:35:09.792
TRE        01:53:14    36:00:00    2017-08-25T19:59:39.792
TRE        01:56:40    31:48:00    2017-08-25T20:06:09.792
TRE        02:26:07    40:12:00    2017-08-25T20:54:39.792
Note: TRE TAROT-La R��union; TCA TAROT-Calern

S.W.K. Emery (UCL-MSSL), A.A. Breeveld (UCL-MSSL), F.E. Marshall (NASA/GSFC),
S.R. Oates (Uni. of Warwick), N.P.M. Kuin (UCL-MSSL), 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.A. Evans (U. Leicester), 
P. Giommi (ASI), C. Gronwall (PSU), J.A. Kennea (PSU), H.A. Krimm (CRESST/GSFC/USRA),
A.Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB), J.A. Nousek (PSU), 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), T. Sakamoto (AGU),
B. Sbarufatti (INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB),
A. Tohuvavohu (PSU), E. Troja (NASA/GSFC/UMCP)
report on behalf of the Swift team:

Swift has performed a series of 525 observations, covering 497 separate
locations within the LVC error region for the GW trigger G299232
convolved with the 2MPZ catalogue (Bilicki et al. 2014, ApJS, 210, 9),
using the 'bayestar-HLV' GW localisation map. The observations currently
span from 11 ks to 256 ks after the LVC trigger.

We have detected an uncatalogued source with the Swift/UVOT, at the position:

RA(J2000) = 01h 40m 08.55s
Dec(J2000)= +34d 34' 03.6" 

We obtain the following magnitude using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373):

Filter          Exp(s)         Mag

u               57             18.00 +/- 0.16

The 57-s exposure started at 2017-08-27 T12:02:34
(about 1.95 days after the LVC trigger).

The magnitude is not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the source
(Schlegel et al. 1998).

No X-ray source was detected at this position, with a 0.3-10 keV upper limit
of 0.13 ct/sec, which corresponds to 5.2e-12 erg/cm^2/s (assuming a typical AGN spectrum).

There is no source in the DSS or SDSS at this position and there is no minor planet at this position.

Further Swift observations are planned.

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

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

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

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

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

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


MASTER OT J033744.97+723159.0 (lipunov, Gorbovskoy, Kornilov et al., GCN LVC 
GCN 21719
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 , 21780
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 ) is cheked recently by MASTER-IAC (Tenerife, Spain). Our 
photometrical results are:

Date        Time             JD         Filter    Mag      A*      Mag_cor

2017-08-27 22:46:16   2457993.4487963     B      18.12    1.41      16.71
2017-08-27 22:50:10   2457993.4515046     V      16.81    1.07      15.74
2017-08-27 22:50:10   2457993.4515046     R      16.04    0.80      15.24
2017-08-27 22:46:16   2457993.4487963     I      15.94    0.51      15.43

* for E(B-V) = 0.3436 and Av = 3.1 * E(B-V)  = 1.065



===========================
Uncorrected magnitude:

B =  18.1226
V = 16.8078
R =  16.0422
I  =  15.9435


E(B-V) = 0.3436   (http://irsa.ipac.caltech.edu/applications/DUST/ )

Av = 3.1 * E(B-V)  => Av = 1.06516 
(http://www.astro.ncu.edu.tw/~wchen/Courses/ISM/11.Extinction.pdf page 17)

=> http://www.astro.ncu.edu.tw/~wchen/Courses/ISM/11.Extinction.pdf (page 22 )

So, MASTER OT J033744.97+723159.0 is reddening (cf,  Im et al, LVC GCN 21723
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 ).

The spectroscopic observations are requared.

This message can be citted.

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

On Aug, 27, 2017, starting at 03.37 (UTC), we obtained three spectra with an
exposure time of 900 sec each, with the ACAM instrument mounted on the William
Herschel Telescope on La Palma (Spain) of the optical transient MASTER
OTJ033744.97+723159.0 reported by Lipunov et al. (GCN 21720
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 ). Analysis using
Gelato suggests that it is a supernova Type IIb before maximum taking the
redshift of NGC1343 of 0.0073 as input.

M. Im, C. Choi, G. Lim, J. Kim, H. M. Lee (SNU), M. J. Kim, H. J. Lee
(KASI) on behalf of the KU collaboration

At 2017-08-28 11:00 (UT), we continued the observation of MASTER
OTJ033744.97+723159.0 near NGC 1343 (Lipunov et al. GCN 21719
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 , 21720
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 ) with
the SQUEAN instrument on the McDonald Observatory���s 2.1m telescope. AB
magnitudes before and after the Galactic extinction correction are given
below.

Before | Extinction | After

g 16.97  1.125  15.85

r  16.49   0.778   15.71

i  16.56    0.578  15.98

The object has brightened by ~0.2 mag in one day and stayed blue in r-i but
has a redder color in g-r (c.f. Lipunov et al. GCN 21736
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 ). The brightening
is consistent with the report that this is a type IIb SN before maximum
(Jonker et al. GCN 21737
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 ).

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

We examined the MAXI/GSC all-sky X-ray images (2-20 keV) obtained
in the orbit and the day after the LVC trigger
G299232 at 2017-08-25 13:13:31 UTC (GCN 21693
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 ).

At the trigger time of G299232,
the high-voltage of MAXI/GSC was off, and it was turned on at T0+1480 sec.
GSC scanned more than 56% of the whole sky in the 92-min orbit,
which includes 69.0% of the 90% region in the bayestar skymap.
scanned from 13:13:31 UTC.
One day image obtained between 08-25 13:13:31 and 08-26 12:03:01 UTC
covers 99.0% of the 90% region in the bayestar skymap.
No significant new source was found in these images
and the 2-20 keV averaged photon counts in the skymap region is 0.41
counts/cm2/sec.
The 3-sigma averaged upper limits
obtained from the one-scan and one-day images in the bayestar skymap are
39 and 12 mCrab, respectively
(see Serino et al., 2017 for the upper limit calculation).

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

Nat Butler (ASU), Alan M. Watson (UNAM), V. Zach Golkhou (University of
Washington), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Eleonora
Troja (GSFC), and Carlos Rom��n-Z����iga (UNAM) report:

We observed the field of MASTER OT J033744.97+723159.0 (Lipunov et al.,
GCN Circ. 21719
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 ) with the COATLI 50-cm telescope and interim imager
(Watson et al. 2016, Proc. SPIE, 9908, 50) at the Observatorio
Astron��mico Nacional on the Sierra de San Pedro M��rtir from 2017-08-28
03:13 to 12:05 obtaining a total of 2.21 hours of observation in the
Bessell B and 1.79 hours in Bessell R.

We detect the OT. Calibrating with respect to the USNO-B1 catalog, we
estimate a preliminary magnitude of

B = 17.21 +/- 0.01
R = 16.15 +/- 0.01

These magnitudes are in the USNO-B1 Vega system and are not corrected for
Galactic extinction in the direction of the OT.

Using the Lupton (2005) conversion from B-R to g-r, we find good agreement between our B-R = 1.06 color and the g-r color reported by Im et al. (GCN 21738
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 ). However, our color is much bluer than the B-R = 2.06 color of Lipunov et al. (GCN 21736
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 ).

We thank the COATLI technical team (Fernando ��ngeles, Rosa Becerra,
Oscar Chapa, Salvador Cuevas, Alejandro Farah, Jorge Fuentes, Rosal��a
Langarica, Fernando Quir��s, and Carlos Tejada) and the staff of the
Observatorio Astron��mico Nacional.
-- 
Dr. Alan M. Watson
Instituto de Astronom��a
Universidad Nacional Aut��noma de M��xico

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

We observed the field of the Optical Transient Discovery by Swift/UVOT (LVG GCN 21733
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 ) with the Asiago 1.82 m Copernico Telescope equipped with AFOSC under poor sky conditions. We do not detected the Swift OT down to the following limits:

Filter (SDSS)  average UT  total Exp (s)  limit (ABmag)
u            20170828.90    1800    22.5
g            20170828.89      270    21.6
r            20170828.88      270    20.8
i            20170828.93      270    21.9
z            20170828.92      900    21.4

We note the presence of the galaxy UGC 1178 at about 5 arcmin from the position of the OT. This galaxy has a redshift z=0.018399, and the projected distance of the OT seen by UVOT would then correspond to about 120 Kpc from the galaxy center.

[GCN OPS NOTE(29aug17):  Per author's request, The Subject-line was changed from "...INAF Asiago/Copernico..."
to "...GRAWITA Asiago/Copernico...". And the the last paragraph "UGC 1178a" was changed to "UGC 1178".

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

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

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

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

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

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

We observed field with Swift/UVOT Optical Transient (LVG GCN 21733
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 ) 
~ 1 day before its detection. No OT detected brighter 19.1.


    Date       UT       Tstart -Ttrig   Exp        Type          Limit

  2017-08-26 05:13:29     0.708 day     180 	  Inspect 	19.1


This message can be citted.

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


We observed the field of MASTER OT J033744.97+723159.0 (Lipunov et al., GCN Circ. 21719
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 ) with our 0.43m robotic telescope at Teide Observatory, Tenerife, Spain.  Observations were taken at two epochs between 2017-08-28T23:51 to 2017-08-29T00:27 and 2017-08-29T03:33 to 2017-08-29T04:09. In total 12 images were taken in the Baader B filter and 12 images in the Baader R filter ranging between 100s-300s in exposure time.

We detect the OT identified by MASTER (Lipunov et al.) at: 03h 37m 44.97s +72d 31m 59.0s.

Our estimated magnitudes are:

R = 16.49 +/- 0.06
B = 17.11 +/- 0.11

These magnitudes are not corrected for Galactic extinction in the direction of the OT.

Further observations are ongoing in conjunction with our own transient search of the LIGO/Virgo bayestar-HLV skymap.


-- The Open University is incorporated by Royal Charter (RC 000391), an exempt charity in England & Wales and a charity registered in Scotland (SC 038302). The Open University is authorised and regulated by the Financial Conduct Authority in relation to its secondary activity of credit broking.

A. Pozanenko (IKI), A. Volnova (IKI), I. Reva (AFIF),  E. Mazaeva (IKI), 
P. Minaev (IKI),  M. Krugov (AFIF) report on behalf of IKI-GW follow-up 
collaboration:

We observed the field of the Optical Transient discovered by Swift/UVOT 
(Emery et al., GCN 21733
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 )  with  Zeiss-1000 1-m telescope of Tien Shan 
Astronomical Observatory starting on 2017-08-28 (UT) 18:54:36. We 
obtained several images in R-filter.  The optical transient (Emery et 
al., GCN 21733
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 ) is not detected in a combined image.  Preliminary 
photometry of the afterglow is following.

Date       UT start   t-T0    Filter    Exp.   OT   Err.  UL
                   (Since LVC,mid, days) (s)         (3 sigma)

2017-08-28 18:54:36  3.24609  R         8*180  n/d  n/d  20.8

Photometry is based on nearby USNO-B1.0 stars (R2 magnitudes).
The nearest galaxy (SDSS J014008.25+343414.8) to the transient position 
in coordinates (J2000) 01 40 08.247 +34 34 14.43 +/- 0.25" is marginally 
detected. The galaxy is at a distance of 11.5 arcsec from the transient 
position. The galaxy photometry is R=21.45 +/- 0.45.

C.M.Copperwheat (LJMU) and I.A.Steele (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), D.Perley (LJMU), E.Pian (Pisa), A.S. Piascik (LJMU), D. Pollacco (Warwick), D. Steeghs (Warwick), N.Tanvir (Leicester), K. Ulaczyk (Warwick), K.Wiersema (Leicester)

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

---

We observed MASTER OTJ033744.97+723159.0, originally reported in GCN #21720
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 , on 2017-08-29 at 04:05UT using the SPRAT spectrograph on the Liverpool Telescope. We concur with the classification reported in GCN #21737
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 : using SNID (Blondin & Tonry, 2007, ApJ, 666, 1024) with the redshift of NGC1343 we believe this transient to be a supernova Type IIb at 2 days before maximum.

We also observed the field of the optical transient discovered with Swift/UVOT (GCN #21733
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 ) in ugriz with the IO:O imager on the Liverpool Telescope, starting at 03:31UT on 2017-08-29. We do not detect an object at these coordinates, as has already been reported by a number of different groups. Our magnitude limits are comparable to those obtained with the Asiago 1.82 m Copernico Telescope (GCN #21745
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 ).


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

On Aug, 29, 2017, starting at 00:45 (UTC), we obtained a u'-band image
with an exposure time of 300 sec, with the ACAM instrument mounted on
the William Herschel Telescope on La Palma (Spain) of the optical
transient reported by Emery et al. GCN21733
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  (see also Tomasella et
al. GCN 21745
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 ). We do not detect a source at the reported position
down to an SDSS-based AB limiting magnitude of u'>24.5 based on the
faintest sources visible in the field. This implies a fading of more
than a factor 350 in about 36.75 hours (assuming the time unit in GCN
21733
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  is UT).

Nat Butler (ASU), Alan M. Watson (UNAM), V. Zach Golkhou (University of
Washington), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Eleonora
Troja (GSFC), and Carlos Rom��n-Z����iga (UNAM) report:

We observed the field of Swift UVOT source (Emery et al., GCN 21733
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 ) with
the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on
the 1.5m Harold Johnson Telescope at the Observatorio Astron��mico Nacional
on Sierra San Pedro M��rtir from 2017/08 29.24 to 2017/08 29.50 UTC (4 days
after GW trigger G299232), obtaining a total 1.8 hours exposure in the g
and r bands, 3.7 hours exposure in the i band, and 1.6 hours exposure in
the Z, Y, J, and H bands.

For a source within the UVOT error circle, in comparison with the SDSS DR9
and 2MASS catalogs, we obtain the following upper limits (3-sigma):

 g > 24.32
 r > 24.09
 i > 24.35
 Z > 23.07
 Y > 22.77
 J > 22.41
 H > 22.04

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.

S.W.K. Emery (UCL-MSSL), A.A. Breeveld (UCL-MSSL), F.E. Marshall (NASA/GSFC),
S.R. Oates (Uni. of Warwick), N.P.M. Kuin (UCL-MSSL), 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.A. Evans (U. Leicester),
P. Giommi (ASI), C. Gronwall (PSU), J.A. Kennea (PSU), H.A. Krimm (CRESST/GSFC/USRA),
A.Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB), J.A. Nousek (PSU), 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), T. Sakamoto (AGU),
B. Sbarufatti (INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB),
A. Tohuvavohu (PSU), E. Troja (NASA/GSFC/UMCP)
report on behalf of the Swift team:

Swift has performed follow-up ToO observations of the optical transient SwiftJ014008.5+343403.6,
reported in Emery et al. (GCN 21733
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 ). We obtained 4 ks of data from 278 ks to 341 ks after the
LVC trigger. This source has faded and is no longer detected in any filter. Earlier MASTER observations
did not detect this source, see Lipunov et al. (GCN 21749
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 ). Other observatories have also not detected
the source (Tomasella et al. (GCN 21745
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 ); Pozanenko et al. (GCN 21754
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 ); Copperwheat et al. (GCN 21755
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 );
Jonker et al. (GCN 21756
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 ); Butler et al. (GCN 21757
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 )).

We obtain preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373):

Filter  Start time     Stop time   Exposure(s)   Magnitude(Vega)
   v     T0+278 ks     T0+341 ks      372            >20.1     
   b     T0+277 ks     T0+340 ks      372            >21.1     
   u     T0+277 ks     T0+340 ks      372            >20.7     
uvw1     T0+276 ks     T0+340 ks      745            >21.0     
uvm2     T0+278 ks     T0+341 ks      514            >20.5     
uvw2     T0+277 ks     T0+340 ks     1491            >21.6     

The magnitudes are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the source
(Schlegel et al. 1998).

Further Swift observations are planned.

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

The HAWC Collaboration performed a follow-up of LIGO trigger G299232. At
the time of the trigger the HAWC local zenith was oriented toward (��, ��) =
(75.0��, 19.0��), so the LV contour had just set in our field of view and no
prompt follow-up was possible.

We searched for long time scale emission during the following transit. The
observations ranged from T0+28ks to T0+87ks. In total 70% of the
probability space was covered. There were no >5 sigma points observed. For
a single transit, the 5 sigma sensitivity to a power law spectrum with a
-2.5 index ranges from ~1.9e-11 >1TeV cm^-2 s^-1 (~1 Crab unit) at dec=-19
to about 10 times higher at the edge of our FOV (45�� from zenith).

At the point of the source reported by Swift/UVOT (RA=01h40m08.55s
DEC=+34d34'03.6", LVC GCN 21733
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 ) we obtain an 95% confidence level upper
limit for >1TeV assuming a -2.5 spectrum of 4.3e-12 cm^-2 s^-1. These
observations were made from T0+62ks to T0+85ks.

We found no significant excess on the error radius corresponding to the
neutrino reported by IceCube (RA=28.2�� DEC= 44.8��, LVC GCN 21698
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 ). For the
location of maximum excess in the error radius we obtain an 95% confidence
level upper limit for >1TeV assuming a -2.5 spectrum of 2.8e-11 cm^-2 s^-1.
These observations were made from T0+64ks to T0+86ks.

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

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

We made a follow-up observation for the reported source in
Emery et al. (GCN 21733
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 )  at  2017-08-29 at  18:40:30  UTC,
with the BFOSC (Beijing Faint Object Spectrograph and Camera)
on the 2.16-m telescope at Xinglong Observatory, China.

No new source was detected in the stacked image with an total
exposure time of 2*600 sec, down to an upper limit of R~22
mag for 3 sigma, calibrated to the nearby SDSS DR9 r magnitudes.

Our results are consistent with the previous reports by
Tomasella et al. (GCN 21745
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 ); Pozanenko et al. (GCN 21754
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 );
Copperwheat et al. (GCN 21755
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 ); Jonker et al. (GCN 21756
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 );
Butler et al. (GCN 21757
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 ), Emery et al., (21758) that
the source was fading greatly,  compared to the brightness
reported in Emery et al. (GCN 21733
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 ) .

We thank the staff of 2.16m telescope in Xinglong observatory,
especially Huijuan Wang and Feng Xiao.

A. Giunta, A. Di Paola, M. Centrone, N. Napoleone (INAF-OAR), G. Greco (Urbino University/INFN Firenze), M. Branchesi (GSSI), L. Amati (INAF-IASF Bo), L. A. Antonelli, (INAF-OAR), S. Ascenzi (INAF-OAR), S. Benetti (INAF-OAPD), M.T. Botticella (INAF-OAC),S. Campana  (INAF-OAB), E. Cappellaro (INAF-OAPD), S. Covino, P. D���Avanzo (INAF-OAB), V. D'Elia (INAF-ASDC), F. Getman (INAF-OAC), A. Grado (INAF-OAC), L. Limatola (INAF-OAC), M. Lisi (INAF-OAR),A. Melandri (INAF-OAB),  L. Nicastro, E. Palazzi, E. Pian (INAF-IASF Bo), 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) and E. Brocato (INAF-OAR) on behalf of GRAvitational Wave Inaf TeAm (GRAWITA) report:

We carried out observa <>tions of LIGO/Virgo G299232 (LVC, GCN 21693
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 ) starting 6.7 hours after the trigger with the 0.9m/0.6m Schmidt telescope located at the Campo Imperatore Observatory (Italy). The observations were taken in the r-sloan band on 2017-08-25 and 2017-08-26 starting respectively at 19:55:57 UT and 20:15:21 UT with relatively good sky conditions. Each night the covered area of ~60 square degrees captured a containment probability of ~7,2% of the cWB map (LVC, GCN 21693
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 ). The area is divided in 5 blocks of 3x3 pointings, each pointing covering 1.15x1.15 square degrees of the sky with 3x120 sec exposure time. The pointing sequence was generated using the GWsky script (https://github.com/ggreco77/GWsky <https://github.com/ggreco77/GWsky>) starting from the high probability region of the bayestar skymap and taking into account the airmass and relative density of nearby galaxies. The first block covers an area where GW skymap overlaps neutrino detection. The 3x3 square degrees pointing blocks are centered on the following coordinates RA, Dec (J2000) and UT times:
1     28.27     44.81     2017-08-25T20:32:06   2017-08-26T20:52:17     
2     31.87    40.28     2017-08-25T21:53:52     2017-08-26T22:15:13     
3     30.22     37.12     2017-08-25T23:14:13     2017-08-26T23:38:52     
4     33.39     43.42     2017-08-26T01:41:21     2017-08-27T01:09:37     
5     34.08     46.50     2017-08-26T02:44:46     2017-08-27T02:46:04      
The limiting magnitude is r ~20.0-22.0 as a function of the observing conditions. Analysis of the images is ongoing.

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:

GCN #21696
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  reported the ANTARES search for upward going High Energy Neutrinos from LIGO/Virgo G299232 event, for which only 42% of the initial 90% C.L contour map was visible (with upward going events).

We report here on a dedicated analysis looking for down-going neutrino candidates in the on-line ANTARES data stream. Cuts on the quality of the track reconstruction and an energy proxy have been used to reduce the false alarm rate in such a way that one event matching in time (+/- 500 s) and direction (90% C.L contour) with G299232 would result in a 3-sigma excess.

The ANTARES visibility, for down-going events, 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/G299232/250817_down.png (gwantares/GW@ANT51)

No down-going muon neutrino candidate events were recorded by ANTARES within the 90% C.L. contour and during a �� 500 s time-window centered on the G299232 event time. An extended search during �� 1 hour yields no coincidence.

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.

LIGO/Virgo G299232: continued WHT observations of the field of SwiftJ014008.5+343403.6

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

On Aug, 30, 2017, starting at 04:54 (UTC), we obtained r',i', and z'-band images
with an exposure time of 3x600, 600, and 600 sec, respectively, with the ACAM
instrument mounted on the William Herschel Telescope on La Palma (Spain) of the
optical transient reported by Emery et al. GCN21733
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 . Seeing conditions were
mediocre with values as large as 2".

We do not detect a source at the reported position down to an SDSS-based AB
limiting magnitude of r', i', z' > 23.5, 21.5, 20.3 based on the faintest
sources detected in the field.

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



We carried out follow up observations of LIGO/Virgo G299232 (LVC, GCN 21693
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 ) with the Schmidt 67/92 telescope located at Cima Ekar (Asiago, Italy). 
Sloan gr-bands images were taken on 2017-08-26 starting from UT 00:10:21. 
The pointing sequence was generated using the GWskyscript (https://github.com/ggreco77/GWsky) starting from the high probability region of 
the bayestar skymap and taking into account the airmass and relative density of nearby galaxies.
Each pointing covers 1x1 square degrees of the sky with 3x180 sec exposure time per band.
The pointing blocks are centered on the following coordinates RA, Dec (J2000) and UT starting times of exposures:

a. 36.76037 +61.84232  2017-08-26T00:06:58  
b. 41.81579 +63.26814  2017-08-26T00:47:35
c. 28.76182 +34.24004  2017-08-26T01:15:13  
d. 29.34192 +32.22710  2017-08-26T01:41:33  
e. 25.77839 +32.19475  2017-08-26T02:06:24  
f. 28.89056 +30.76806  2017-08-26T02:30:09

The single exposure is characterised by an AB limiting magnitude of r > 22.

We also observed with the Copernico 1.82m telescope (Cima Ekar, Asiago, Italy) and equipped with AFOSC instrument. 
Sloan g and r-bands images (FOV = 8.8 X 8.8 arcmin) 
were taken on 2017-08-26 starting from UT 00:18:10 either of seven nearby galaxies whose location on the sky and distance falls in the 90% volume reported by the 
BAYESTAR probability sky map (Singer et al. 2016) and listed by Cook et al. 2017 in GCN n. 21707 (pointing 1-7), 
and generated using the GWskyscript (https://github.com/ggreco77/GWsky; pointing 8-11):

1.  IC 1695                   2017-08-26T01:44:39
2.  UGC01400                  2017-08-26T01:53:39
3.  UGC00774                  2017-08-26T01:59:13
4.  IC0260                    2017-08-26T02:07:20
5.  NGC0326                   2017-08-26T02:13:02
6.  SDSS J014929.88+123032.4  2017-08-26T02:18:27
7.  MRK 0567                  2017-08-26T02:30:00
8.  27.83787 +33.058979       2017-08-26T00:15:07
9.  30.54151 +52.365807       2017-08-26T00:29:12
10. 24.86730 +18.979811       2017-08-26T01:04:49
11. 28.69988 +31.314634       2017-08-26T01:29:22

Preliminary analysis do not show new transients in these fields.

Liming Rui (Tsinghua University),  Xiaofeng Wang (Tsinghua university), 
Danfeng Xiang (Tsinghua Univeristy), Han Lin (Tsinghua Unviersity), and 
Huijuan Wang (NAOC)

We obtained an optical spectrum (range 380-870 nm) of MASTER 
OTJ033744.97+723159.0 (Lipunov et al. GCN 21720
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 , GCN2136
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 ), on 
2017-08-29.54UT  with the 2.16-m telescope at Xinglong Station of National 
Astronomical Observatories of China (NAOC) on BFOSC (Beijing Faint Object 
Spectrograph and Camera).

The spectrum is consistent with a type IIb supernova a few days before the 
maximum light, using SN96cb data as the spectral templates.

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

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

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

N.M. Budnev, O. Gress, K. Ivanov, S.Yazev, Yu. Ishmuhamedova-Rabinovich,
Irkutsk State University

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

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

Analyzing MASTER database archive images of MASTER OT J033744.97+723159.0 
(Lipunov et al. GCN 21720
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 , GCN2136
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 ) we found 1 image on 2017-08-19 
22:32:24.443 with clearly seen OT with unfiltered m_OT=18.6 .

During Fermi GBM trigger 521687456  inspection MASTER-Kislovodsk observed 
the area  RA(2000)=(18.200 +29.540) +-5.25deg GRB_error (statistical only) 
on 2017-07-14 22:54:12UT with mlim=18.7 .

There is SIWFT/UVOT source (Emery et al., LVC GCN 21733
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 , 21758
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 ) from 
LIGO/VIRGO G299232 error-box (Siellez et al., GCN 21693
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 )
with m_OT~18.7 on 2017-07-14 22:54:12UT

The archival image is available at:
http://master.sai.msu.ru/static/OT/MASTERKislovodsk20170714.jpg

We are gratiful all follow up photometry (Im et al. 
GCN21723
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 ; Im et al. GCN21738
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 ; Butler et al. GCN21742
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 , Roberts et al.
GCN 21752
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 ) and spectral (Jonker et al. GCN 21737
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 ; Roberts et al. GCN 21752
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 ; Copperwheat et al. 
GCN21755
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 ; Liming Rui et al. GCN 21780
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 ) observations.

This SN IIb is placed very far from  NGC 1343 galaxy center at distance 
~20 kpc. The  massive star progenitor in the no star formation 
area  is very strange.

This message can be citted.

P. Reig (U. of Crete/FORTH) & G.V. Panopoulou (Caltech) reporting on behalf 
of the RoboPol collaboration: 

We observed the optical transient OTJ033744.97+723159.0 (Lipunov et al. GCN 21720
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 , 
GCN 21736
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 ), on 2017-08-29.07UT  with the RoboPol polarimeter at the Skinakas observatory 
1.3-m telescope. Preliminary analysis shows that the R-band fractional polarization of 
the source is 1.8+-0.47%. It is consistent with polarization of nearby field stars. 
Further observations are scheduled.

J.W. Broderick (ASTRON), A. Rowlinson (UvA, ASTRON), 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 August 30 - September 4, we observed a large fraction of the localisation error range of the Advanced LIGO/Virgo trigger G299232 (LVC, GCN 21693
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 ) 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 225 min using a number of separate 25-min snapshots.     

The beam centres are given below (RA and Dec in degrees); the Bayestar-HLV localisation was used as a basis for calculating the coordinates of the beams. Two beams in separate pointings were centred on the IceCube neutrino candidate at RA = 28.2 deg, Dec = 44.8 deg (Bartos et al., GCN 21694
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 ; Bartos et al., GCN 21698
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 ). Furthermore, one beam was centred on the optical transient discovered by Swift/UVOT at RA = 25.035625 deg, Dec = 34.567667 deg (Emery et al., GCN 21733
Loading...
 
 ).  

Analysis is ongoing. We thank the ASTRON Radio Observatory for promptly scheduling the observations.


Pointing 1
(integration time 225 min over the period 2017-08-30 23:00 UTC - 2017-08-31 06:21 UTC)

1) 34.039151    46.299866
2) 35.248501    48.949799
3) 28.200000    44.800000
4) 31.322127    48.348415
5) 36.756176    44.251317
6) 37.965526    46.901250

Pointing 2
(integration time 225 min over the period 2017-08-30 23:26 UTC - 2017-08-31 06:47 UTC)

1) 35.780064    51.725205
2) 36.750925    54.437875
3) 31.502071    50.889684
4) 32.472933    53.602354
5) 39.087195    49.848056
6) 40.058057    52.560726

Pointing 3
(integration time 225 min over the period 2017-08-31 23:00 UTC - 2017-09-01 06:21 UTC)

1) 29.306644    35.778068
2) 30.478008    38.389034
3) 25.035625    34.567667
4) 27.105198    37.906547
5) 31.508089    33.649589
6) 32.679454    36.260555

Pointing 4
(integration time 225 min over the period 2017-08-31 23:26 UTC - 2017-09-01 06:47 UTC)

1) 31.825000    41.000000
2) 33.084178    43.610966
3) 28.199341    40.517513
4) 28.200000    44.800000
5) 34.191481    38.871521
6) 35.450659    41.482487

Pointing 5
(integration time 225 min over the period 2017-09-03 01:00-08:21 UTC)

1) 41.738945    68.095823
2) 43.350996    70.808493
3) 34.635623    67.260303
4) 36.247674    69.972972
5) 47.230217    66.218674
6) 48.842268    68.931344

Pointing 6
(integration time 225 min over the period 2017-09-03 01:26-08:47 UTC)

1) 44.937500    79.572222
2) 44.267884    76.796335
3) 31.320689    78.289239
4) 31.990306    81.065126
5) 57.884694    78.079318
6) 58.554311    80.855205

Pointing 7
(integration time 225 min over the period 2017-09-04 00:00-07:21 UTC)

1) 37.337896    57.197845
2) 38.228521    59.934164
3) 32.518303    56.247531
4) 33.408928    58.983851
5) 41.266865    55.411839
6) 42.157490    58.148159

Pointing 8
(integration time 225 min over the period 2017-09-04 00:26-07:47 UTC)

1) 39.119146    62.670484
2) 40.170071    65.406804
3) 33.432096    61.720170
4) 34.483021    64.456490
5) 43.755272    60.884478
6) 44.806196    63.620798

A. Pozanenko (IKI), A. Volnova (IKI), E. Mazaeva (IKI), B. Hafizov 
(UBAI), O. Burhonov (UBAI)  report on behalf of IKI-GW follow-up 
collaboration:

We observed the field of the Optical Transient discovered by Swift/UVOT 
(Emery et al., GCN 21733
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 )  with  AZT-22 telescope of Maidanak 
observatory starting on 2017-08-28 (UT) 21:25:37. We obtained several 
images in R-filter.  The optical transient (Emery et al., GCN 21733
Loading...
 
 ) is 
not detected in a combined image.  Preliminary  photometry of the field 
is following.

Date       UT start  t-T0     Filter      Exp.   OT   Err.  UL
                    (Since LVC,mid, days) (s)         (3 sigma)

2017-08-28 21:25:37  3.34167  R           3600   n/d  n/d   23.0

Photometry is based on nearby USNO-B1.0 stars (R2 magnitudes).

Po-Chieh Yu (NCU), C.-C. Ngeow (NCU), W.-H. Ip (NCU), Albert Kong (NTHU) on
behalf of the GROWTH (Global Relay of Observatories Watching Transients
Happen collaboration)


We observed the possible OTs for LIGO/Virgo G299232, one at/near NGC
1343 (MASTER
OT J033744.97+723159.0; GCN 21719
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 ), and the other one discovered by
SWIFT/UVOT (GCN 21733
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 ) with Lulin One-meter Telescope (LOT). We detected OT
J033744.97+723159.0 and calibrated with respect to the APASS catalog.


Summary of the observations:


20170828 20:05:45 UT B 360s 17.32 +/- 0.01

20170828 20:00:15 UT V 300s 16.48 +/- 0.01


20170829 19:46:14 UT B 360s 17.19 +/- 0.01

20170829 19:52:30 UT V 300s 16.33 +/- 0.01


These magnitudes are on the Vega system and are not corrected for Galactic
extinction in the direction of the OT.


The second OT was observed once and we did not have any detection at the
reported location (which confirms the follow-up announcements in GCN 21754
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and 21757
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 ).


We thank the staff of the Lulin observatory in Taiwan.

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), S.W.K. Emery (UCL-MSSL), P. Giommi (ASI), C. Gronwall
(PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien
(GSFC/UMBC), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), 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), A. Tohuvavohu (PSU), E. Troja (NASA/GSFC/UMCP)
report on behalf of the Swift team:

Swift has performed a series of 768 observations, covering 653 separate
locations within the LVC error region for the GW trigger G299232
convolved with the 2MPZ catalogue (Bilicki et al. 2014, ApJS, 210, 9),
using the 'bayestar-HLV' 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 11 ks to 758 ks after the
LVC trigger, and cover 75.9 sq degrees on the sky (corrected for
overlaps). This covers 8.3% of the probability in the 'bayestar-HLV'
skymap, and 15% after convolving with the 2MPZ galaxy catalogue, as
described by Evans et al., (2016, MNRAS,  462, 1591). A list of all
observations and exposure times is in GraceDB.

In total, we have detected 51 X-ray sources. 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
  * 1 source of rank 2
  * 30 sources of rank 3
  * 20 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 2 source
=============

This is a catalogued X-ray source which was detected at a level well
above the catalogued flux. However, this is an RS CVn variable star, so
this is not surprising. We do not consider this the counterpart.

  
  Source 11:
  =============
    RA: 	 26.7914 ( = 01h 47m 9.94s) J2000
    Dec:	 +23.7585 ( = +23d 45' 30.6") J2000
    Error:	 +4.1 (arcsec, radius, 90% confidence).
    Peak Rate:	 7.6e-02 +/- 1.5e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 3.3e-12 +/- 6.3e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Catalogued:  Yes
    Cat Source:  1RXS J014709.9+234529 in the ROSAT/RASSFSC catalogue
    Separation:  1.7" from the XRT source
    Cat Rate:	 2.6e-02 +/- 1.1e-02 ct/sec 
    Cat Flux:	 7.3e-13 +/- 3.0e-13 erg cm^-2 s^-1 (0.3-10 keV)
		 so the source	is 3.6-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 `V* BE Ari' is 4.1" away.
    There is 1 2MASS object within the source's 3-sigma error radius.


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 7:
  =============
    RA: 	 28.8331 ( = 01h 55m 19.94s) J2000
    Dec:	 +41.4501 ( = +41d 27' 00.4") J2000
    Error:	 +6.1 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.0e-02 +/- 1.2e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 8.7e-13 +/- 5.3e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 3.7e-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.
    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 8:
  =============
    RA: 	 57.4297 ( = 03h 49m 43.13s) J2000
    Dec:	 +75.2688 ( = +75d 16' 07.7") J2000
    Error:	 +5.9 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.7e-02 +/- 7.3e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 7.4e-13 +/- 3.1e-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.
    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 9:
  =============
    RA: 	 26.4272 ( = 01h 45m 42.53s) J2000
    Dec:	 +32.7277 ( = +32d 43' 39.7") J2000
    Error:	 +6.8 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.8e-02 +/- 1.1e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 1.2e-12 +/- 4.6e-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.
    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 13:
  =============
    RA: 	 275.5870 ( = 18h 22m 20.88s) J2000
    Dec:	 -24.5012 ( = -24d 30' 04.3") J2000
    Error:	 +6.9 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.2e-02 +/- 9.4e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 9.6e-13 +/- 4.0e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 6.4e-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 `PMN J1822-2429' is 3.9" away.
    There are 3 2MASS objects within the source's 3-sigma error radius.

  
  Source 14:
  =============
    RA: 	 280.4037 ( = 18h 41m 36.89s) J2000
    Dec:	 -26.9052 ( = -26d 54' 18.7") J2000
    Error:	 +6.5 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.3e-02 +/- 4.7e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 5.5e-13 +/- 2.0e-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.
    There are 2 2MASS objects within the source's 3-sigma error radius.

  
  Source 15:
  =============
    RA: 	 30.5062 ( = 02h 02m 1.49s) J2000
    Dec:	 +39.7221 ( = +39d 43' 19.6") J2000
    Error:	 +7.5 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.7e-02 +/- 7.2e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 7.4e-13 +/- 3.1e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 4.2e-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.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 16:
  =============
    RA: 	 30.8523 ( = 02h 03m 24.55s) J2000
    Dec:	 +39.8555 ( = +39d 51' 19.8") J2000
    Error:	 +7.9 (arcsec, radius, 90% confidence).
    Peak Rate:	 4.2e-02 +/- 3.1e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 1.8e-12 +/- 1.3e-12 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 2.4e-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.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 18:
  =============
    RA: 	 277.0265 ( = 18h 28m 6.36s) J2000
    Dec:	 -26.7567 ( = -26d 45' 24.1") J2000
    Error:	 +6.0 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.5e-02 +/- 9.8e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 1.1e-12 +/- 4.2e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 6.3e-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 `HD 169938' is 3.5" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 20:
  =============
    RA: 	 21.1039 ( = 01h 24m 24.94s) J2000
    Dec:	 +8.4009 ( = +08d 24' 03.2") J2000
    Error:	 +5.2 (arcsec, radius, 90% confidence).
    Peak Rate:	 3.3e-02 +/- 1.0e-02 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:	 4.7e-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.
    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 J01242495+0824076' is 4.5" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 23:
  =============
    RA: 	 280.4462 ( = 18h 41m 47.09s) J2000
    Dec:	 -31.1682 ( = -31d 10' 05.5") J2000
    Error:	 +5.5 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.9e-02 +/- 9.7e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 1.2e-12 +/- 4.2e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 3.2e-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 is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 24:
  =============
    RA: 	 280.4270 ( = 18h 41m 42.48s) J2000
    Dec:	 -31.1927 ( = -31d 11' 33.7") J2000
    Error:	 +4.6 (arcsec, radius, 90% confidence).
    Peak Rate:	 5.0e-02 +/- 1.2e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 2.1e-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 25:
  =============
    RA: 	 35.0606 ( = 02h 20m 14.54s) J2000
    Dec:	 +50.7456 ( = +50d 44' 44.2") J2000
    Error:	 +9.8 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.0e-02 +/- 7.8e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 8.6e-13 +/- 3.3e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 2.9e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)

       so the source is not above the RASS 3-sigma upper limit.
    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 27:
  =============
    RA: 	 35.3623 ( = 02h 21m 26.95s) J2000
    Dec:	 +51.4366 ( = +51d 26' 11.8") J2000
    Error:	 +5.1 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.3e-02 +/- 4.6e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 5.4e-13 +/- 2.0e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 1.5e-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 29:
  =============
    RA: 	 20.0708 ( = 01h 20m 16.99s) J2000
    Dec:	 +12.0556 ( = +12d 03' 20.2") J2000
    Error:	 +6.1 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.3e-02 +/- 4.9e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 5.7e-13 +/- 2.1e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 9.8e-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.
    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 `NVSS J012016+120326' is 6" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 30:
  =============
    RA: 	 25.0723 ( = 01h 40m 17.35s) J2000
    Dec:	 +23.4559 ( = +23d 27' 21.2") J2000
    Error:	 +6.4 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.0e-02 +/- 7.8e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 8.6e-13 +/- 3.3e-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.
    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 `2MASS J01401722+2327211' is 1.6" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 32:
  =============
    RA: 	 29.7004 ( = 01h 58m 48.10s) J2000
    Dec:	 +36.3610 ( = +36d 21' 39.6") J2000
    Error:	 +5.1 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.4e-02 +/- 8.6e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 1.0e-12 +/- 3.7e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 3.6e-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 are 3 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 34:
  =============
    RA: 	 30.2909 ( = 02h 01m 9.82s) J2000
    Dec:	 +44.1712 ( = +44d 10' 16.3") J2000
    Error:	 +5.8 (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)
    RASS UL:	 4.9e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)

       so the source is not above the RASS 3-sigma upper limit.
    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 36:
  =============
    RA: 	 30.1611 ( = 02h 00m 38.66s) J2000
    Dec:	 +44.4550 ( = +44d 27' 18.0") J2000
    Error:	 +5.7 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.3e-02 +/- 6.0e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 5.6e-13 +/- 2.6e-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.
    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 `4C 44.05' is 4.2" away.
  
  Source 41:
  =============
    RA: 	 35.7720 ( = 02h 23m 5.28s) J2000
    Dec:	 +43.5135 ( = +43d 30' 48.6") J2000
    Error:	 +6.1 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.2e-02 +/- 7.5e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 9.4e-13 +/- 3.2e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 7.6e-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 is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 43:
  =============
    RA: 	 25.0451 ( = 01h 40m 10.82s) J2000
    Dec:	 +34.5945 ( = +34d 35' 40.2") J2000
    Error:	 +7.6 (arcsec, radius, 90% confidence).
    Peak Rate:	 4.3e-03 +/- 3.3e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 1.9e-13 +/- 1.4e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 2.4e-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 0.3-sigma level.
    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.
  
  Source 44:
  =============
    RA: 	 24.9350 ( = 01h 39m 44.40s) J2000
    Dec:	 +34.6730 ( = +34d 40' 22.8") J2000
    Error:	 +6.4 (arcsec, radius, 90% confidence).
    Peak Rate:	 4.1e-03 +/- 2.6e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 1.8e-13 +/- 1.1e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 2.0e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)

       so the source is not above the RASS 3-sigma upper limit.
    The source may be fading, at the 0.6-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 45:
  =============
    RA: 	 25.0033 ( = 01h 40m 0.79s) J2000
    Dec:	 +34.5832 ( = +34d 34' 59.5") J2000
    Error:	 +5.7 (arcsec, radius, 90% confidence).
    Peak Rate:	 3.2e-03 +/- 1.7e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 1.4e-13 +/- 7.5e-14 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.
    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.
  
  Source 46:
  =============
    RA: 	 25.0002 ( = 01h 40m 0.05s) J2000
    Dec:	 +34.6823 ( = +34d 40' 56.3") J2000
    Error:	 +6.4 (arcsec, radius, 90% confidence).
    Peak Rate:	 4.2e-03 +/- 2.0e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 1.8e-13 +/- 8.7e-14 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 2.0e-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 are 2 GWGC or 2MPZ galaxies within 200 kpc of the source.
      and consistent (within 3-sigma) with the distance to the GW
object.
  
  Source 47:
  =============
    RA: 	 24.8943 ( = 01h 39m 34.63s) J2000
    Dec:	 +34.4368 ( = +34d 26' 12.5") J2000
    Error:	 +7.8 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.5e-02 +/- 1.7e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 6.4e-13 +/- 7.2e-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 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.
  
  Source 48:
  =============
    RA: 	 25.1053 ( = 01h 40m 25.27s) J2000
    Dec:	 +34.3855 ( = +34d 23' 07.8") J2000
    Error:	 +6.9 (arcsec, radius, 90% confidence).
    Peak Rate:	 6.8e-03 +/- 5.3e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 2.9e-13 +/- 2.3e-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.
  
  Source 49:
  =============
    RA: 	 24.8491 ( = 01h 39m 23.78s) J2000
    Dec:	 +34.5412 ( = +34d 32' 28.3") J2000
    Error:	 +6.2 (arcsec, radius, 90% confidence).
    Peak Rate:	 3.5e-03 +/- 1.9e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 1.5e-13 +/- 8.2e-14 erg cm^-2 s^-1 (0.3-10 keV)
    1SXPS UL:	 1.4e-03 ct/sec, (0.3-10 keV)
       so the source is 1.1-sigma above the 1SXPS 3-sigma upper limit.
    RASS UL:	 3.4e-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 `LAMOST J013923.93+343234.0' is 5.9" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 50:
  =============
    RA: 	 25.0324 ( = 01h 40m 7.78s) J2000
    Dec:	 +34.6094 ( = +34d 36' 33.8") J2000
    Error:	 +7.1 (arcsec, radius, 90% confidence).
    Peak Rate:	 4.0e-03 +/- 4.6e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 1.7e-13 +/- 2.0e-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.
    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 51:
  =============
    RA: 	 25.1025 ( = 01h 40m 24.60s) J2000
    Dec:	 +34.5437 ( = +34d 32' 37.3") J2000
    Error:	 +7.5 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.7e-03 +/- 2.2e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 1.2e-13 +/- 9.5e-14 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 are 3 GWGC or 2MPZ galaxies within 200 kpc of the source.
      and consistent (within 3-sigma) with the distance to the GW
object.
  
  Source 52:
  =============
    RA: 	 24.9789 ( = 01h 39m 54.94s) J2000
    Dec:	 +34.6917 ( = +34d 41' 30.1") J2000
    Error:	 +7.9 (arcsec, radius, 90% confidence).
    Peak Rate:	 4.7e-03 +/- 2.9e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 2.0e-13 +/- 1.2e-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.
    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.
  
  Source 53:
  =============
    RA: 	 24.8754 ( = 01h 39m 30.10s) J2000
    Dec:	 +34.6003 ( = +34d 36' 01.1") J2000
    Error:	 +8.4 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.1e-02 +/- 2.3e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 8.9e-13 +/- 1.0e-12 erg cm^-2 s^-1 (0.3-10 keV)
    1SXPS UL:	 1.4e-02 ct/sec, (0.3-10 keV)
       so the source is not above the 1SXPS 3-sigma upper limit.
    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 1.3-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.


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. Therefore, we do not list details of the sources
here.

This circular is an official product of the Swift team.

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

In response to the LIGO/Virgo GW trigger G299232
(GCN #21693
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 , T0=2017-08-25, 13:13:37.983 UTC):

We searched for Ultra High Energy (UHE) neutrinos with energies
above ~ 1e17 eV in data collected with the Surface Detector (SD) of
the Pierre Auger Observatory in a [-500,500] second interval about
the LIGO-Virgo trigger G299232 as well as 1 day after it.

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

The field of view (fov) where the SD of Auger is sensitive to UHE neutrinos
(corresponding to inclined directions with respect to the vertical relative
to the ground) was coincident with only a small fraction of the most
updated
LIGO 90% localization region (bayestar-HLV.fits.gz) at the time T0 of the
merger alert. Some parts of the 90% region closest to the Northern
hemisphere
are never visible in the Auger fov.

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

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/Virgo event G299232 (2017-08-25 13:13:37.977 UTC, hereafter T0;
LIGO/Virgo Collaboration GCN Circ. 21693
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 ).

No triggered KW event happened from ~4400 s before and ~0.8 days
after T0. The closest waiting-mode event was ~0.2 days after T0.
Using waiting-mode data within the interval T0 +/- 100 s,
we found no significant (> 5 sigma) excess over the background
in both KW detectors on temporal scales from 2.944 s to 100 s.

We estimate an upper limit (90% conf.) on the 10 keV ��� 10 MeV fluence
to 8.4x10^-7 erg/cm^2 for a burst lasting less than 2.944 s and having a
typical KW short GRB spectrum (an exponentially cut off power law with
alpha=-0.5 and Ep=500 keV). For a typical long GRB spectrum (the Band
function with alpha=-1, beta=-2.5, and Ep=300 keV), the corresponding
limiting peak flux is 3.0x10^-7 erg/cm^2/s (10 keV - 10 MeV, 2.944 s scale).

All the quoted values are preliminary.

A. Pozanenko (IKI), E. Mazaeva (IKI), A. Volnova (IKI), S. Schmalz 
(KIAM), N. Tungalag (Research Center of Astronomy and Geophysics MAS), 
I. Molotov (KIAM) report on behalf of IKI-GW follow-up collaboration:

We observed  the field of  LIGO/Virgo trigger G299232 (LVC GCN 21693
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 ) 
and the error circle of IceCube candidate X1, hereafter ICX1 (GCNs 
21694
Loading...
 
 , 21698
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 ) with  wide FOV VT-78a telescope of Khureltogot observatory 
starting on 2017-08-25 (UT) 15:24:13. We obtained several unfiltered 
images with the two time series, each centered to the position of 
localization reported in GCN 21694
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 , and GCN 21698
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 , respectively.
Preliminary results of our analysis of the fields are following.


Date       UT start  t-T0      Exp.   UL       FOV Center   Coverage
                  (Since G299232 (s) (5 sigma)  RA, Dec.     %
                    mid, days)                  degrees

2017-08-25 15:24:13  0.11289   60*60  19.3     27.1, 45.1  85.1
2017-08-25 16:32:52  0.16054   60*60  19.4     28.2, 44.8  78.3

Photometry is based on USNO-B1.0 stars (R2 magnitudes).
Total coverage of the error region of ICX1 (GCN 21698
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 ) is 85.7%. The map 
of the coverage can be found at
http://grb.rssi.ru/GW170825_G299232/LVC_IC_Khureltogot_v3.png

We found no new or unknown objects in the combined images up to the 
limits listed above.
We investigate all sources above S/N > 10 (~17m) and found no 
significant variability of the sources between the two epochs. We found 
no significantly more brighter sources which could be galaxies 
(including galaxy   2MASX J01571097+4715588 listed as Nearby Galaxies in 
the Localization Volume (GCN 21707
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 ))  than their R-magnitudes presented 
in the USNO-B1.0 catalog.

A. M. Read (U. Leicester), A. Tiengo (IUSS Pavia), R. Salvaterra
(INAF-IASF Milano), E. Troja (NASA/GSFC), and R. D. Saxton (ESAC)
report:

We analyzed the XMM-Newton slews made after the LIGO/Virgo G299232/
GW170825 event. The first two slews intercepting the GW localization
map cover it for about 41.2 square degrees:

Obs ID�������� |������ date������ |���� T-T_GW���� |coverage of localization map
9325000003 | 2017-09-07 |���� 12.7 d���� |�� 8.0 deg2
9325100002 | 2017-09-09 |���� 14.7 d���� |�� 33.2 deg2

For each dataset (EPIC pn data with the Medium filter) we performed the
source detection following the method described in Troja et al. 2016
(ApJ, 822, L8).
Typical sensitivity limits of slew observations are ~6e-13 ergs cm-2 s-1
in the 0.2-2 keV band and ~4e-12 ergs cm-2 s-1 in the 2-12 keV band. The
list of the most significant 0.2-12 keV band detections (DET_ML>12) in
each slew intersecting the GW170825 localization map, with no counterpart
within 30 arcsec in the ROSAT All Sky Survey (Boller et al. 2016, A&A
588, A103) and with no X-ray sources with compatible position and flux
detected in archival XMM-Newton observations, is reported below.
The flux and counts are computed in the 0.2-12 keV energy band.
Rank (1-4, 1 most likely, 4 least likely) indicates how likely the object
is to be the GW counterpart.

----------
Revolution 3250, Observation ID 9325000003
RA (deg) DEC (deg) CTS  DET_ML EXPOSURE(s) FLUX(ergs cm-2 s-1) Rank
269.3143 -25.1624  24.1 12.1   4.9         4.9e-11             4,extended
----------
Revolution 3251, Observation ID 9325100002
RA (deg)  DEC (deg) CTS  DET_ML EXPOSURE(s) FLUX(ergs cm-2 s-1) Rank
243.0149  20.2417   4.2  17.3   7.1         6.0e-12             4

J.W. Broderick (ASTRON), A. Rowlinson (UvA, ASTRON), 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 September 23-28, we observed a large fraction of the localisation region of the Advanced LIGO/Virgo trigger G299232 (LVC, GCN 21693
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 ) 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 225 min using a number of separate 25-min snapshots.     

The beam centres are given below (RA and Dec in degrees); the Bayestar-HLV localisation was used as a basis for calculating the coordinates of the beams. The setup is identical to the previous set of LOFAR follow-up observations described in Broderick et al., GCN 21809
Loading...
 
 . Two beams in separate pointings were centred on the IceCube neutrino candidate at RA = 28.2 deg, Dec = 44.8 deg (Bartos et al., GCN 21694
Loading...
 
 ; Bartos et al., GCN 21698
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 ). Furthermore, one beam was centred on the optical transient discovered by Swift/UVOT at RA = 25.035625 deg, Dec = 34.567667 deg (Emery et al., GCN 21733
Loading...
 
 ).  

Analysis is ongoing. We thank the ASTRON Radio Observatory for scheduling the observations.


Pointing 1
(integration time 225 min over the period 2017-09-23 21:00 UTC - 2017-09-24 04:21 UTC)

1) 34.039151    46.299866
2) 35.248501    48.949799
3) 28.200000    44.800000
4) 31.322127    48.348415
5) 36.756176    44.251317
6) 37.965526    46.901250

Pointing 2
(integration time 225 min over the period 2017-09-23 21:26 UTC - 2017-09-24 04:47 UTC)

1) 35.780064    51.725205
2) 36.750925    54.437875
3) 31.502071    50.889684
4) 32.472933    53.602354
5) 39.087195    49.848056
6) 40.058057    52.560726

Pointing 3
(integration time 225 min over the period 2017-09-24 21:00 UTC - 2017-09-25 04:21 UTC)

1) 29.306644    35.778068
2) 30.478008    38.389034
3) 25.035625    34.567667
4) 27.105198    37.906547
5) 31.508089    33.649589
6) 32.679454    36.260555

Pointing 4
(integration time 225 min over the period 2017-09-24 21:26 UTC - 2017-09-25 04:47 UTC)

1) 31.825000    41.000000
2) 33.084178    43.610966
3) 28.199341    40.517513
4) 28.200000    44.800000
5) 34.191481    38.871521
6) 35.450659    41.482487

Pointing 5
(integration time 225 min over the period 2017-09-26 21:11 UTC - 2017-09-27 04:32 UTC)

1) 41.738945    68.095823
2) 43.350996    70.808493
3) 34.635623    67.260303
4) 36.247674    69.972972
5) 47.230217    66.218674
6) 48.842268    68.931344

Pointing 6
(integration time 225 min over the period 2017-09-26 21:37 UTC - 2017-09-27 04:58 UTC)

1) 44.937500    79.572222
2) 44.267884    76.796335
3) 31.320689    78.289239
4) 31.990306    81.065126
5) 57.884694    78.079318
6) 58.554311    80.855205

Pointing 7
(integration time 225 min over the period 2017-09-27 22:00 UTC - 2017-09-28 05:21 UTC)

1) 37.337896    57.197845
2) 38.228521    59.934164
3) 32.518303    56.247531
4) 33.408928    58.983851
5) 41.266865    55.411839
6) 42.157490    58.148159

Pointing 8
(integration time 225 min over the period 2017-09-27 22:26 UTC - 2017-09-28 05:47 UTC)

1) 39.119146    62.670484
2) 40.170071    65.406804
3) 33.432096    61.720170
4) 34.483021    64.456490
5) 43.755272    60.884478
6) 44.806196    63.620798

R. Mirzoyan on behalf of the MAGIC Collaboration

In response to the LIGO/Virgo GW event G299232 (GCN 21693
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 ), the MAGIC Cherenkov Telescopes located at the Observatory El Roque de Los Muchachos of the Istituto de Astrofisica de Canarias (IAC) observed the following targets reported by follow-up observations:

Target-1: the IceCube muon-1 region (GCN 21694
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  and GCN 21698
Loading...
 
 );
Target-2: the optical transient reported by MASTER OTJ033744.97+723159.0 (GCN 21719
Loading...
 
 , GCN 21720
Loading...
 
 , GCN 21736
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 );
Target-3: Swift-UVOT transient (GCN 21733
Loading...
 
 ).

Target-1 
=======

A scan of the region defined by the neutrino-muon detected by IceCube (RA: 28.2 deg DEC: 44.8 deg sigma: 3.8 deg, GCN 21698
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 ) was performed through four different pointings on August 26, between 03:03 and 05:28 UT

Pointing-1: RA: +01h 52m 48.0s DEC: +44d 47m 60.0s; Effective observation time: 0.51 hr 
Pointing-2: RA: +01h 46m 24.0s DEC: +44d 47m 60.0s; Effective observation time: 0.57 hr
Pointing-3: RA: +01h 49m 36.0s DEC: +46d 12m 00.0s; Effective observation time: 0.51 hr
Pointing-4: RA: +01h 49m 36.0s DEC: +43d 12m 00.0s; Effective observation time: 0.51 hr

corresponding to a region of ~10 deg^2, RA: ~26-29 deg DEC:~ 43-46 deg. 

Weather conditions were not ideal, with somewhat reduced transmission because of the Sahara dust in the atmosphere.

A preliminary skymap was built. No excess is found. Very preliminary upper limits at E>200 GeV are ~1.5e-11 ph/cm2/s, valid only at the center of the field of view.


Target-2 
=======

MAGIC observed at the position of MASTER OTJ033744.97+723159.0, RA: 03h 37m 44.97s DEC: +72d 31m 59.0s (GCN 21719
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 ) on August 28, from 03:24 to 05:26 UT for 1.92 hrs effective time and on August 29, from 01:50 and 03:15 UT for 0.97 hrs effective time.

Fair weather conditions, partially affected by dust and moderate atmospheric absorption.

No significant excess was found. The preliminary upper limit on the flux at E>200 GeV is 5.5e-12 ph/cm2/s. 


Target-3 
=======

MAGIC observed at the position of the unidentified transient detected by Swift/UVOT RA: 01h 40m 08.55s DEC: +34d 34m 03.6s (GCN 21733
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 ) on August 29 at 03:23 UT for 0.8 hrs effective time.

Fair weather conditions, partially affected by dust and moderate atmospheric absorption.

No significant excess was found. The preliminary upper limit on the flux at E>200 GeV is 2.1e-11 ph/cm2/s. 

----------
MAGIC is a system of two 17m-diameter Imaging Atmospheric Cherenkov Telescopes located at the the Observatory El Roque de Los Muchachos of the Istituto de Astrofisica de Canarias (IAC), Spain and designed to perform gamma-ray astronomy in the energy range from 50 GeV to greater than 50 TeV, (https://magic.mpp.mpg.de).

D.Steeghs, D.Pollacco, K.Ulaczyk, R.Cutter, R.West, A.Levan���, J.Lyman���, P.Chote, J.McCormac (U. Warwick)  
D.K.Galloway, E.Rol, E.Thrane���, K.Ackley, A.Casey��� (Monash U.)  
V.Dhillon, M.Dyer, S.Littlefair, E.Daw, J.Mullaney���, L.Makrygianni���, J.Maund (U. Sheffield)
G.Ramsay (Armagh O.)
P.O'Brien, R.Starling���, R.Eyles��� (U. Leicester)
���S.Poshyachinda, S.Aukkaravittayapun, U.Sawangwit, S.Awiphan, D.Mkrtichian (NARIT)

On behalf of the GOTO collaboration:

We report on optical observations with the SuperWASP Exoplanet camera array on La Palma, in response to G299232 (GCN #21693
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 ). Targeted observations containing approximately 50% of the total source location probability were performed between 23:24 UT 25/08/2017 and 05:52 UT 26/08/2017. This coverage is based on the bayestar-HLV skymap with combined Ligo/Virgo constraints and is focused on the northern hemisphere region of highest probability density. Each pointing consisted of 3x30s exposures in the clear filter and pointings were repeated between 38 and 50 times during that observing window.  These regions were also observed the following night between 23:20 UT 26/08/2017 and 05:51 UT 27/08/2017.  

Observations at the same position were stacked and crossmatched with APASS for photometric calibration. Conditions were not fully stable and our 5-sigma limiting magnitudes in these stacks range from 15.9 to 17.1 (V-band equivalent). No new transients were identified in these data.

We examined our ���images��� for ���evidence of the Swift/UVOT source ���J014008.5+343403.6 (GCN #21733
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 )���. ��� Our stacks at this position reach V=17.0 and precede the SWIFT detection. A difference image analysis shows no evidence for a source at the reported position during either of our nights of data.

J.W. Broderick (ASTRON), K. Gourdji (UvA), A. Rowlinson (UvA, ASTRON),
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 November 18-26, we observed a large fraction of the
localisation region of the Advanced LIGO/Virgo trigger G299232 (LVC,
GCN 21693
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 ) 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 225 min using a number of separate 25-min snapshots.

The beam centres are given below (RA and Dec in degrees); the
Bayestar-HLV localisation was used as a basis for calculating the
coordinates of the beams. The setup is identical to the previous sets
of LOFAR follow-up observations described in Broderick et al., GCN
21809
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  and GCN 21962
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 . Two beams in separate pointings were centred on
the IceCube neutrino candidate at RA = 28.2 deg, Dec = 44.8 deg
(Bartos et al., GCN 21694
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 ; Bartos et al., GCN 21698
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 ). Furthermore, one
beam was centred on the optical transient discovered by Swift/UVOT at
RA = 25.035625 deg, Dec = 34.567667 deg (Emery et al., GCN 21733
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 ).

Analysis is ongoing. We thank the ASTRON Radio Observatory for
scheduling the observations.


Pointing 1
(integration time 225 min over the period 2017-11-18 18:11 UTC -
2017-11-19 01:32 UTC)

1) 34.039151    46.299866
2) 35.248501    48.949799
3) 28.200000    44.800000
4) 31.322127    48.348415
5) 36.756176    44.251317
6) 37.965526    46.901250

Pointing 2
(integration time 225 min over the period 2017-11-18 18:37 UTC -
2017-11-19 01:58 UTC)

1) 35.780064    51.725205
2) 36.750925    54.437875
3) 31.502071    50.889684
4) 32.472933    53.602354
5) 39.087195    49.848056
6) 40.058057    52.560726

Pointing 3
(integration time 225 min over the period 2017-11-20 18:11 UTC -
2017-11-21 01:32 UTC)

1) 29.306644    35.778068
2) 30.478008    38.389034
3) 25.035625    34.567667
4) 27.105198    37.906547
5) 31.508089    33.649589
6) 32.679454    36.260555

Pointing 4
(integration time 225 min over the period 2017-11-20 18:37 UTC -
2017-11-21 01:58 UTC)

1) 31.825000    41.000000
2) 33.084178    43.610966
3) 28.199341    40.517513
4) 28.200000    44.800000
5) 34.191481    38.871521
6) 35.450659    41.482487

Pointing 5
(integration time 225 min over the period 2017-11-24 18:11 UTC -
2017-11-25 01:32 UTC)

1) 41.738945    68.095823
2) 43.350996    70.808493
3) 34.635623    67.260303
4) 36.247674    69.972972
5) 47.230217    66.218674
6) 48.842268    68.931344

Pointing 6
(integration time 225 min over the period 2017-11-24 18:37 UTC -
2017-11-25 01:58 UTC)

1) 44.937500    79.572222
2) 44.267884    76.796335
3) 31.320689    78.289239
4) 31.990306    81.065126
5) 57.884694    78.079318
6) 58.554311    80.855205

Pointing 7
(integration time 225 min over the period 2017-11-25 18:11 UTC -
2017-11-26 01:32 UTC)

1) 37.337896    57.197845
2) 38.228521    59.934164
3) 32.518303    56.247531
4) 33.408928    58.983851
5) 41.266865    55.411839
6) 42.157490    58.148159

Pointing 8
(integration time 225 min over the period 2017-11-25 18:37 UTC -
2017-11-26 01:58 UTC)

1) 39.119146    62.670484
2) 40.170071    65.406804
3) 33.432096    61.720170
4) 34.483021    64.456490
5) 43.755272    60.884478
6) 44.806196    63.620798

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

From 2018 April 7-15, we observed a large fraction of the localisation
region of the Advanced LIGO/Virgo trigger G299232 (LVC, GCN 21693
Loading...
 
 )
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 245 min using a number of separate 25-min snapshots, as
well as a single 20-min snapshot.

The beam centres are given below (RA and Dec in degrees); the
Bayestar-HLV localisation was used as a basis for calculating the
coordinates of the beams. The pointing setup is identical to the
previous sets of LOFAR follow-up observations described in Broderick
et al., GCN 21809
Loading...
 
 , GCN 21962
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  and GCN 22172
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 . Two beams in separate
pointings were centred on the IceCube neutrino candidate at RA = 28.2
deg, Dec = 44.8 deg (Bartos et al., GCN 21694
Loading...
 
 ; Bartos et al., GCN
21698
Loading...
 
 ). Furthermore, one beam was centred on the optical transient
discovered by Swift/UVOT at RA = 25.035625 deg, Dec = 34.567667 deg
(Emery et al., GCN 21733
Loading...
 
 ).

Analysis is ongoing. We thank the ASTRON Radio Observatory for
scheduling the observations.

Pointing 1
(integration time 245 min over the period 2018-04-07 08:48 UTC -
2018-04-07 16:56 UTC)

1) 34.039151    46.299866
2) 35.248501    48.949799
3) 28.200000    44.800000
4) 31.322127    48.348415
5) 36.756176    44.251317
6) 37.965526    46.901250

Pointing 2
(integration time 245 min over the period 2018-04-07 08:27 UTC -
2018-04-07 16:35 UTC)

1) 35.780064    51.725205
2) 36.750925    54.437875
3) 31.502071    50.889684
4) 32.472933    53.602354
5) 39.087195    49.848056
6) 40.058057    52.560726

Pointing 3
(integration time 245 min over the period 2018-04-08 08:25 UTC -
2018-04-08 16:33 UTC)

1) 29.306644    35.778068
2) 30.478008    38.389034
3) 25.035625    34.567667
4) 27.105198    37.906547
5) 31.508089    33.649589
6) 32.679454    36.260555

Pointing 4
(integration time 245 min over the period 2018-04-08 08:04 UTC -
2018-04-08 16:12 UTC)

1) 31.825000    41.000000
2) 33.084178    43.610966
3) 28.199341    40.517513
4) 28.200000    44.800000
5) 34.191481    38.871521
6) 35.450659    41.482487

Pointing 5
(integration time 245 min over the period 2018-04-14 08:51 UTC -
2018-04-14 16:59 UTC)

1) 41.738945    68.095823
2) 43.350996    70.808493
3) 34.635623    67.260303
4) 36.247674    69.972972
5) 47.230217    66.218674
6) 48.842268    68.931344

Pointing 6
(integration time 245 min over the period 2018-04-14 08:30 UTC -
2018-04-14 16:38 UTC)

1) 44.937500    79.572222
2) 44.267884    76.796335
3) 31.320689    78.289239
4) 31.990306    81.065126
5) 57.884694    78.079318
6) 58.554311    80.855205

Pointing 7
(integration time 245 min over the period 2018-04-15 08:30 UTC -
2018-04-15 16:38 UTC)

1) 37.337896    57.197845
2) 38.228521    59.934164
3) 32.518303    56.247531
4) 33.408928    58.983851
5) 41.266865    55.411839
6) 42.157490    58.148159

Pointing 8
(integration time 245 min over the period 2018-04-15 08:09 UTC -
2018-04-15 16:17 UTC)

1) 39.119146    62.670484
2) 40.170071    65.406804
3) 33.432096    61.720170
4) 34.483021    64.456490
5) 43.755272    60.884478
6) 44.806196    63.620798