LIGO/Virgo S190828j

The LIGO Scientific Collaboration and the Virgo Collaboration report:

We identified the compact binary merger candidate S190828j during
real-time processing of data from LIGO Hanford Observatory (H1), LIGO
Livingston Observatory (L1), and Virgo Observatory (V1) at 2019-08-28
06:34:05.756 UTC (GPS time: 1251009263.756). The candidate was found
by the GstLAL [1], CWB [2], PyCBC Live [3], MBTAOnline [4], and SPIIR
[5] analysis pipelines.

S190828j is an event of interest because its false alarm rate, as
estimated by the online analysis, is 8.5e-22 Hz, or about one in 1e14
years. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S190828j

The classification of the GW signal, in order of descending
probability, is BBH (>99%), Terrestrial (<1%), BNS (<1%), MassGap
(<1%), or NSBH (<1%).

Assuming the candidate is astrophysical in origin, there is strong
evidence against the lighter compact object having a mass < 3 solar
masses (HasNS: <1%). Using the masses and spins inferred from the
signal, there is strong evidence against matter outside the final
compact object (HasRemnant: <1%).

One sky map is available at this time and can be retrieved from the
GraceDB event page:
 * bayestar.fits.gz, an updated localization generated by BAYESTAR
[6], distributed via GCN notice about 16 minutes after the candidate

For the bayestar.fits.gz sky map, the 90% credible region is 603 deg2.
Marginalized over the whole sky, the a posteriori luminosity distance
estimate is 2276 +/- 538 Mpc (a posteriori mean +/- standard
deviation).

For further information about analysis methodology and the contents of
this alert, refer to the LIGO/Virgo Public Alerts User Guide
<https://emfollow.docs.ligo.org/userguide/>.

 [1] Messick et al. PRD 95, 042001 (2017)
 [2] Klimenko et al. PRD 93, 042004 (2016)
 [3] Nitz et al. PRD 98, 024050 (2018)
 [4] Adams et al. CQG 33, 175012 (2016)
 [5] Qi Chu, PhD Thesis, The University of Western Australia (2017)
 [6] Singer & Price PRD 93, 024013 (2016)

F. Longo (Univ. Trieste, and INFN Trieste), C. Pittori, F. Verrecchia
(SSDC, and

INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), M. Cardillo,

C. Casentini, G. Piano, A. Ursi (INAF/IAPS), F. Lucarelli (SSDC, and
INAF/OAR),

A. Bulgarelli, V. Fioretti, N. Parmiggiani (INAF/OAS-Bologna), M. Pilia

(INAF/OA-Cagliari), report on behalf of the AGILE Team:


In response to the LIGO/Virgo GW event S190828j at T0 = 2019-08-28
06:34:05.756 (UT),

a preliminary analysis of the AGILE minicalorimeter (MCAL) triggered data
found

no event  candidates within a time interval covering -/+ 15 sec from the

LIGO/Virgo T0.


At the T0, about 40% of the S190828j 90 c.l. localization region was
accessible

to the AGILE MCAL.Three-sigma upper limits (ULs) are obtained for a 1 s

integration time at different celestial positions within the accessible
S190828j

localization region, from a minimum of 1.55E-06 erg cm^-2 to a maximum of

7.31E-06 erg cm^-2 (assuming as spectral model a single power law with
photon

index 1.5).


The AGILE-MCAL detector is a CsI detector with a 4 pi FoV, sensitive in the

energy range 0.4-100 MeV. Additional analysis of AGILE data is in progress.

The HAWC Collaboration (https://www.hawc-observatory.org) reports:

The HAWC Collaboration performed a follow-up of the gravitational wave
trigger S190828j (GCN #25497
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 ). At the time of the trigger the HAWC
local zenith was oriented towards (RA, Dec) = (337.2 deg, 18.9 deg).
40% of the GW candidate sky location probability fell within our
observable field of view (0-45 deg zenith angle).

We performed a search for a short timescale emission using 6 sliding
time windows (dt = 0.3s, 1s, 3s, 10s, 30s and  100s), shifted forward
in time by 20% of their width. We searched the 95% probability
containment area in a timescale-dependent time period, from t0-5dt to
t0+10dt, where t0 is the time of the GW trigger.

No significant gamma-ray detection above the background was observed.

The sensitivity of this analysis is greatly dependent on zenith angle,
ranging from 15.3 deg to 45.0 deg for the area searched in this
analysis. The 5sigma detection sensitivity to a 1s (100s) burst in the
80-800GeV energy range goes from 1.7e-06 erg/cm^2 to 1.1e-04 erg/cm^2
(9.1e-06 erg/cm^2 to 5.0e-04 erg/cm^2), depending on the zenith
angle.

HAWC is a TeV gamma ray water Cherenkov array located in the state of
Puebla, Mexico. It is sensitive to the energy range ~0.1-100TeV, and
monitors 2/3 of the sky every day with an instantaneous field-of-view
of ~2 sr.

E. Bozzo (ISDC/UniGE, Switzerland), S. Schanne (CEA, France)
V. Savchenko, C. Ferrigno (ISDC/UniGE, Switzerland)
J. Rodi (IAPS-Roma, Italy)
A. Coleiro (APC, France)
S. Mereghetti (INAF IASF-Milano, Italy)

on behalf of the INTEGRAL multi-messenger collaboration:
https://www.astro.unige.ch/cdci/integral-multimessenger-collaboration

Using INTEGRAL/SPI-ACS realtime data (following [1]) we have performed a 
search for a prompt gamma-ray counterpart of S190828j (GCN 25497
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 ).

At the time of the event (2019-08-28 06:34:05 UTC, hereafter T0), 
INTEGRAL was operating in nominal mode. The peak of the event 
localization probability was at an angle of 83 deg with respect to the 
spacecraft pointing axis. This orientation implies strongly suppressed 
(11% of optimal) response of ISGRI, strongly suppressed (31% of optimal) 
response of IBIS/Veto, and near-optimal (80% of optimal) response of 
SPI-ACS.

The background within +/-300 seconds around the event was very stable 
(excess variance 1.2).

We have performed a search for any impulsive events in INTEGRAL SPI-ACS 
(as described in [2]) data.

We do not detect any significant counterparts and estimate a 3-sigma 
upper limit on the 75-2000 keV fluence of 2e-07 erg/cm^2 (within the 50% 
probability containment region of the source localization) for a burst 
lasting less than 1 s with a characteristic short GRB spectrum (an 
exponentially cut off power law with alpha=-0.5 and Ep=600 keV) 
occurring at any time in the interval within 300 s around T0. For a 
typical long GRB spectrum (Band function with alpha=-1, beta=-2.5, and 
Ep=300 keV), the derived peak flux upper limit is ~1.7e-07 (5.6e-08) 
erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range.

For the mean reported distance 2276.0 Mpc this corresponds to the limit 
on the total isotropic equivalent energy in 1 s of 1.2e+50 erg for the 
short GRB spectrum and for a long GRB spectrum isotropic equivalent 
luminosity in 1 s (8 s) of 1.1e+50 erg/s (3.5e+49 erg/s)

We report for completeness and in order of FAP, all excesses identified 
in the search region. We find 9 background excesses:

scale | T | S/N | luminosity ( x 1e+50 erg/s) | FAP
5.2 | -276 | 3.9 | 9.22 +/- 3.03 +/- 5.34 | 0.2
0.55 | -20.1 | 3.6 | 27.9 +/- 9.38 +/- 16.2 | 0.223
0.1 | -1.25 | 3.1 | 5.75 +/- 2.22 +/- 3.33 | 0.249
0.2 | 10.7 | 3.5 | 4.58 +/- 1.56 +/- 2.65 | 0.393
1.6 | 37.3 | 3.1 | 13.9 +/- 5.48 +/- 8.05 | 0.46
1.4 | -135 | 3.6 | 17.3 +/- 5.86 +/- 10 | 0.547
0.05 | -7.63 | 3.6 | 9.67 +/- 3.17 +/- 5.6 | 0.564
0.55 | 63.4 | 3.5 | 27.3 +/- 9.38 +/- 15.8 | 0.807
0.95 | -60.6 | 3.2 | 19.3 +/- 7.12 +/- 11.2 | 0.83

Note that FAP estimates (especially at timescales above 2s) may be 
possibly further affected by enhanced non-stationary local background 
noise. This list excludes any excesses for which FAP is close to unity.



All results quoted are preliminary.

This circular is an official product of the INTEGRAL Multi-Messenger team.

[1] Savchenko et al. 2017, A&A, 603, A46

[2] Savchenko et al. 2012, A&A, 541A, 122S

The LIGO Scientific Collaboration and Virgo Collaboration report:

We have updated the skymap for the compact binary merger candidate S190828j
(GCN 25497
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 ). The event's properties can be found at this URL:

https://gracedb.ligo.org/superevents/S190828j/

bayestar.fits.gz is the preferred sky map at this time and can be retrieved
from the

GraceDB event page:

 * bayestar.fits.gz, an updated localization generated by BAYESTAR [1],
distributed via GCN update notice about 1.5 hours after the candidate

The 90% credible region is 587 deg2. Marginalized over the whole sky, the a
posteriori luminosity distance estimate is 1803 +/- 423 Mpc (a posteriori
mean +/- standard deviation).

Note that S190828j (GCN 25497
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 ) and S190828l (GCN 25503
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 ) are distinct events
that occurred 21 minutes apart.

For further information about analysis methodology and the contents of this
alert, refer to the LIGO/Virgo Public Alerts User Guide <
https://emfollow.docs.ligo.org/userguide/>.

 [1] Singer & Price PRD 93, 024013 (2016)

F. Longo (Univ. Trieste, and INFN Trieste), C. Pittori, F. Verrecchia 
(SSDC, and
INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), M. Cardillo,
C. Casentini, G. Piano, A. Ursi (INAF/IAPS), F. Lucarelli (SSDC, and 
INAF/OAR),
A. Bulgarelli, V. Fioretti, N. Parmiggiani (INAF/OAS-Bologna), M. Pilia
(INAF/OA-Cagliari), report on behalf of the AGILE Team:

In response to the LIGO-Virgo GW event S190828j at T0 = 2019-08-28 
06:34:05.756
UT a preliminary analysis of the AGILE exposure at T0 shows that the 
Gamma-Ray
Imaging Detector (GRID) exposure covered more than 15% of the 90% c.l.
localization region (LR) (32% of 90% c.l. localization region (LR) is 
occulted
by Earth).

We performed an analysis of the GRID data in the energy range 50 MeV -
10 GeV on T0, where good exposure of the S190828j 90% c.l. LR was available.

No candidate gamma-ray transient was detected.

The following preliminary GRID values of 3-sigma upper limit (UL) are 
obtained:

from 7.9e-07 to 9.74e-06 erg cm^-2 s^-1, with exposure of about 36% of 
the LR
over the time interval ( T0 -2s ; T0 + 2s );
from 6.5e-07 to 6.1e-06 erg cm^-2 s^-1, with exposure of about 34% of the LR
over the time interval ( T0s ; T0 + 5s );
from 3.39e-07 to 6e-06 erg cm^-2 s^-1, with exposure of about 34% of the LR
over the time interval ( T0s ; T0 + 10s );
from 1.3e-07 to 5.91e-06 erg cm^-2 s^-1, with exposure of about 36% of 
the LR
over the time interval ( T0s ; T0 + 100s );

A map in Galactic coordinates showing the AGILE FoV at T0 is available 
at the
site:
https://tools.ssdc.asi.it/ImgView/Agile/aitoff_MULTImap2019-08-28-4s_mod19

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

M. Ageron (CPPM/CNRS), B. Baret (APC/CNRS), A. Coleiro (APC/Universite de Paris), M. Colomer (APC/Universite de Paris), D. Dornic (CPPM/CNRS), A. Kouchner (APC/Universite de Paris), 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 S190828j event using the 90% contour of the Initial bayestar probability
map provided by the GW interferometers (GCN#25497
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  <https://gcn.gsfc.nasa.gov/gcn3/25497.gcn3
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 >). The ANTARES visibility at the time of the
alert, together with the 50% and 90% contours of the probability map are shown at http://antares.in2p3.fr/GW/S190828j_Initial.png <http://antares.in2p3.fr/GW/S190828j_Initial.png>.
Considering the location probability provided by the LIGO/Virgo collaborations, there is a
53.1% chance that the GW emitter was in the ANTARES **upgoing** field of view at the time of
the alert.

No up-going muon neutrino candidate events were recorded in the ANTARES sky during a
+/-500s time-window centered on the time 2019-08-28 06:34:05 and in the 90% contour of the S190828j
event. The expected number of atmospheric background events in the region visible by ANTARES is
1.67e-04 in the +/- 500s time window. An extended search during +/- 1 hour gives no
up-going muon neutrino coincidence. The expected number of atmospheric background events in the
region visible by ANTARES is 1.20e-03 in this larger time window.

ANTARES is the largest undersea neutrino detector, installed in the Mediterranean Sea, and it is
primarily sensitive to neutrinos in the TeV-PeV  energy range. At 10 TeV, the median angular
resolution for muon neutrinos is about 0.5 degrees. In the range 1-100 TeV ANTARES has a
competitive sensitivity to this position in the sky.

S. Sugita, M. Serino (AGU),
N. Kawai, M. Sugizaki (Tokyo Tech), H. Negoro (Nihon U.),
M. Nakajima, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.),
T. Mihara, T. Tamagawa, M. Matsuoka (RIKEN),
T. Sakamoto, H. Nishida, A. Yoshida (AGU),
Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.),
M. Shidatsu (Ehime U.), M. Oeda, K. Shiraishi (Tokyo Tech),
S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, N. Isobe,
R. Shimomukai, M. Tominaga (JAXA),
Y. Ueda, A. Tanimoto, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake
(Kyoto U.),
H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.),
M. Yamauchi, S. Iwahori, Y. Kurihara, K. Kurogi, K. Miike (Miyazaki U.),
T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU)
report on behalf of the MAXI team:

We examined MAXI/GSC all-sky X-ray images (2-20 keV)
after the LVC trigger S190828j at 2019-08-28 06:34:05.756 UTC (GCN 25497
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 ).

At the trigger time of S190828j, the high-voltage of MAXI/GSC was on.
The instantaneous field of view of GSC at the GW trigger time covered
2% of the 90% credible region
of the bayestar sky map, in which we found no significant new X-ray source.
The first one-orbit (92 min) scan observation with GSC after the event
covered 94%
of the 90% credible region of the bayestar skymap from 06:34:05 to
08:06:01 UTC (T0+0 to T0+5516 sec).

No significant new source was found in the region in the one-orbit
scan observation.
A typical 1-sigma averaged upper limit obtained in one scan observation
is 20 mCrab at 2-20 keV.

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

IceCube Collaboration (http://icecube.wisc.edu/) reports:

Searches [1,2] for track-like muon neutrino events detected by IceCube
consistent with the sky localization of gravitational-wave candidate
S190828j
 in a time range of 1000 seconds [3] centered on the alert event time
(2019-08-28 06:25:45.756 UTC to 2019-08-28 06:42:25.756 UTC) have been
performed.  During this time
period IceCube was collecting good quality data.  No significant track-like
events are found in spatial coincidence of S190828j calculated from the map
circulated in the 3-Update notice.

IceCube's sensitivity assuming an E^-2 spectrum (E^2 dN/dE) to neutrino
point sources within the locations spanned by the 90% spatial  containment
of S190828j ranges from  0.034 to 0.841 GeV cm^-2 in a 1000 second
time window.

The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector
operating at the geographic South Pole, Antarctica. The IceCube realtime
alert point of contact can be reached at roc@icecube.wisc.edu


[1] Bartos et al. arXiv:1810.11467
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  (2018) and Countryman et
al.arXiv:1901.05486
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  (2019)
[2] Braun et al., Astroparticle Physics 29, 299 (2008)
[3] Baret et al., Astroparticle Physics 35, 1 (2011)

P. Veres (UAH) reports on behalf of the Fermi-GBM Team and the
GBM-LIGO/Virgo group:

For S190828j and using the updated bayestar skymap (GCN 25504
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 ), Fermi-GBM
was observing 83% of the localization probability at event time.

There was no Fermi-GBM onboard trigger around the event time of the
LIGO/Virgo detection of GW trigger S190828j (GCN 25497
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 ). An automated,
blind search for short gamma-ray bursts below the onboard triggering
threshold in Fermi-GBM also identified no counterpart candidates. The GBM
targeted search, the most sensitive, coherent search for GRB-like signals,
was run from +/-30 s around merger time, and also identified no counterpart
candidates.

We therefore set upper limits on impulsive gamma-ray emission. Using the
representative soft, normal, and hard GRB-like templates described in
arXiv:1612.02395
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 , we set the following 3 sigma flux upper limits over
10-1000 keV (in units of erg/s/cm^2):


Timescale  Soft     Normal   Hard
--------------------------------------
0.128 s:   5.5e-07  7.5e-07  1.7e-06
1.024 s:   1.8e-07  2.8e-07  6.8e-07
8.192 s:   7.1e-08  1.3e-07  2.5e-07

Assuming the median luminosity distance of 1800 Mpc (z=0.34) from the GW
detection, we estimate the following intrinsic luminosity upper limits over
the 1 keV-10 MeV energy range (in units of 10^50 erg/s):

Timescale  Soft          Normal      Hard
------------------------------------
0.128 s:     3.4          4.1         16
1.024 s:     1.1          1.5         6.2
8.192 s:     0.44         0.71        2.3

F. Piron (CNRS/IN2P3/LUPM), N. Omodei (Stanford Univ.), F.��Longo (Univ. 
and INFN Trieste), M. Arimoto (Kanazawa Univ.), D. Kocevski (NASA/MSFC), 
M. Axelsson (KTH and Stockholm Univ.) and E. Bissaldi (Politecnico and 
INFN Bari)��report on behalf of the Fermi-LAT Collaboration:

We have searched data collected by the Fermi Large Area Telescope (LAT) 
on Aug 28, 2019, for possible high-energy (E > 100 MeV) gamma-ray 
emission in spatial/temporal coincidence with the LIGO/Virgo trigger 
S190828j��(GCN 25497
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 ).

We define "instantaneous coverage" as the integral over the region of 
the LIGO probability map that is within the LAT field of view at a given 
a time, and "cumulative coverage" as the integral of the instantaneous 
coverage over time. Fermi-LAT had a null instantaneous coverage of the 
LIGO probability region at the time of the trigger (T0 = 2019-08-28 
06:34:05.756UTC), and reached ~52%��cumulative coverage after 10 ks.

We performed a search for a transient counterpart within the observed 
region of the 90% contour of the LIGO map in a fixed time window from T0 
to T0 + 10 ks. No significant sources were found.

We also performed a search which adapted the time interval of the 
analysis to the exposure of each region of the sky, and no additional 
excesses were found.

Energy flux upper bounds for the fixed time interval between 100 MeV and 
1 GeV for this search vary between 4.3e-10 and 8.5e-8 [erg/cm^2/s].

The Fermi-LAT point of contact for this event is Frederic Piron 
(piron@in2p3.fr).

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.

Keto D. Zhang, Sergiy Vasylyev, Thomas de Jaeger, WeiKang Zheng,
Andrew Hoffman, Benjamin E. Stahl, Yukei Murakami, and Alexei V. Filippenko
(UC Berkeley) report on behalf of the Lick/KAIT GW follow-up team:

The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, observed the 90% region of the gravitational-wavei
event S190828j (GCN 25497
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 ) detected by LIGO/Virgo. More than one
thousand galaxies were selected from the Glade catalog V1.0
(Dalya et al., 2018, MNRAS, 479, 2374; http://aquarius.elte.hu/glade/)
according to their priority score. KAIT observed 84 of them based on
their priority scores and elevation visibility, with each clear-filter
exposure time being 60 s. The first image was taken at 07:10:51, Aug.
28th UT, about 37 minutes after the trigger, and the last image at
12:59:08 UT. Our typical limiting mag is 19.0. No viable counterparts
were identified and the analysis is ongoing. A full list of galaxies
observed by KAIT is given below.

GladeID   UT(Aug28)  RA_J2000   Dec_J2000
-----------------------------------------------
G1411338  07:10:51  00:00:42.1697  +62:28:27.9912
G0108194  07:12:09  00:02:34.6301  +59:10:45.9012
G1437181  07:13:18  00:04:43.1198  +60:54:53.7408
G1376191  07:14:27  00:04:50.1787  +61:08:02.7816
G0915623  07:15:37  00:06:55.8847  +60:56:16.6632
G0040914  07:16:46  00:09:18.455   +60:52:27.1164
G0023757  07:17:54  00:10:06.7973  +61:36:45.864
G0960102  07:19:03  00:10:20.1641  +60:46:39.81
G0857314  07:20:12  00:11:03.7274  +59:44:23.334
G0286480  07:21:22  00:12:01.2106  +59:41:10.5108
G1256548  07:22:31  00:13:02.2044  +59:55:55.596
G0382218  07:23:40  00:15:37.1263  +59:11:37.6332
G0178384  07:24:50  00:16:02.4991  +59:29:08.79
G0354798  07:25:59  00:16:41.8795  +61:02:41.0064
G1236761  07:27:08  00:16:55.019   +62:32:58.0488
G1104060  07:28:17  00:17:17.959   +62:50:17.9016
G0197398  07:29:27  00:19:02.5733  +63:03:57.7152
G1108946  07:30:36  00:19:38.0712  +62:25:39.9828
G0410793  07:31:47  00:21:19.2425  +63:18:59.4468
G0412316  07:32:57  00:23:11.5109  +63:14:27.8376
G1335438  07:34:06  00:24:22.8192  +63:29:54.6576
G0040683  07:35:18  00:25:05.8135  +62:09:01.3248
G1311682  07:36:27  00:28:01.1556  +61:13:34.5828
G1353194  07:37:34  00:28:32.2651  +62:25:30.162
G1411338  08:16:50  00:00:42.1697  +62:28:27.9912
G1437181  08:17:59  00:04:43.1198  +60:54:53.7408
G1376191  08:19:09  00:04:50.1787  +61:08:02.7816
G0915623  08:20:18  00:06:55.8847  +60:56:16.6632
G0040914  08:21:27  00:09:18.455   +60:52:27.1164
G0023757  08:22:37  00:10:06.7973  +61:36:45.864
G0960102  08:23:46  00:10:20.1641  +60:46:39.81
G0857314  08:25:08  00:11:03.7274  +59:44:23.334
G0286480  08:26:17  00:12:01.2106  +59:41:10.5108
G1256548  08:27:25  00:13:02.2044  +59:55:55.596
G0382218  08:28:35  00:15:37.1263  +59:11:37.6332
G0178384  08:29:44  00:16:02.4991  +59:29:08.79
G0354798  08:30:53  00:16:41.8795  +61:02:41.0064
G1236761  08:32:02  00:16:55.019   +62:32:58.0488
G1104060  08:33:12  00:17:17.959   +62:50:17.9016
G0197398  08:34:21  00:19:02.5733  +63:03:57.7152
G1108946  08:35:33  00:19:38.0712  +62:25:39.9828
G0410793  08:36:42  00:21:19.2425  +63:18:59.4468
G0412316  08:37:49  00:23:11.5109  +63:14:27.8376
G1335438  08:38:59  00:24:22.8192  +63:29:54.6576
G0040683  08:40:08  00:25:05.8135  +62:09:01.3248
G1353194  08:41:17  00:28:32.2651  +62:25:30.162
G0341361  08:42:26  00:28:34.0399  +61:37:03.1656
G0040540  08:43:38  00:32:50.7516  +64:01:35.1156
G1125714  08:44:47  00:33:18.3127  +61:27:43.344
G0195596  08:45:56  00:35:06.0497  +62:46:14.376
G0133562  08:47:08  00:35:47.389   +64:04:54.9552
G0083833  08:48:17  00:39:39.6461  +62:56:06.2232
G0304019  08:49:26  00:44:44.6424  +62:03:38.97
G0332087  08:50:48  00:45:19.158   +65:27:13.1436
G1232494  08:52:43  00:46:53.2234  +63:08:07.764
G0058140  08:53:53  00:49:35.4175  +64:51:58.608
G0026909  08:55:02  00:52:34.2317  +63:11:28.7484
G0215715  08:56:11  00:52:46.4971  +65:50:02.7564
G0211497  08:57:21  00:55:03.9209  +62:44:28.3308
G0463440  08:58:30  00:58:21.8878  +63:37:25.1796
G0107445  08:59:39  01:01:53.0525  +63:15:32.0112
G0414645  09:00:49  01:06:47.1456  +64:40:42.9204
G0297094  09:01:58  01:14:20.381   +63:43:33.4128
G0544341  09:03:07  01:15:33.0602  +63:37:00.0624
G0043239  09:04:17  01:18:36.6046  +63:48:39.78
G0858497  09:05:36  02:08:29.8543  +64:31:02.7048
G0461687  12:39:17  22:37:39.4555  +51:03:50.5224
G1468559  12:40:26  22:37:49.2626  +50:50:28.4928
G1369384  12:41:35  22:41:18.6254  +52:11:20.5224
G1286759  12:42:45  22:42:40.2319  +53:50:01.9716
G0329445  12:43:54  22:43:08.5181  +51:34:07.9464
G1187210  12:45:03  22:44:21.6871  +53:37:55.5168
G0518266  12:46:19  23:16:30.0146  +57:53:27.7872
G0464426  12:47:26  23:18:14.2603  +58:32:36.6108
G0417225  12:48:38  23:20:05.3686  +58:21:10.7064
G0894934  12:49:47  23:21:59.502   +57:00:07.4448
G0322333  12:50:56  23:27:15.4762  +58:45:09.7236
G0312471  12:52:08  23:30:53.401   +57:16:46.7184
G1042257  12:53:17  23:32:23.0126  +58:24:54.0576
G1074414  12:54:26  23:33:31.5746  +57:52:19.3836
G0085132  12:55:38  23:35:10.979   +59:34:58.7856
G0843567  12:56:47  23:36:16.4354  +58:41:06.7344
G0307552  12:57:56  23:37:05.4859  +59:24:34.956
G0218409  12:59:08  23:40:07.6903  +59:59:08.9016

S. D. Barthelmy (NASA/GSFC), A. Y. Lien (GSFC/UMBC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
A. P. Beardmore (U. Leicester), M. G. Bernardini (INAF-OAB),
A. A. Breeveld (MSSL-UCL), 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 (ASI-SSDC), S. Emery (UCL-MSSL),
P. A. Evans (U. Leicester), P. Giommi (ASI), C. Gronwall (PSU),
D. Hartmann (Clemson U.), J. A. Kennea (PSU), H. A. Krimm (NSF),
N. P. M. Kuin (UCL-MSSL), D. B. Malesani (DTU Space),
F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), 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. J. Page (UCL-MSSL), 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 S190828j (LIGO/VIRGO Collaboration GCN Circ. 25497
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 ),
where T0 is the LVC trigger time (2019-08-28T06:34:05.756 UTC).

The center of the BAT FOV at T0 is
RA = 214.805 deg,
DEC = -26.634 deg,
The roll angle is 299.633 deg.
The BAT Field of View (>10% partial coding) covers 34.90% of the integrated
LVC localization probability, and 34.83% of the galaxy convolved
probability (Evans et al. 2016).

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. 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 ~ 9.00 x 10^-8 erg/s/cm^2.

No event data are available within T0 +/- 100 s.

BAT retains decreased, but significant, sensitivity to rate increases for
gamma-ray events outside of its FOV. About 44.63% 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 higher than those
within the FOV.

The results of the BAT analysis are available at
https://swift.gsfc.nasa.gov/results/BATbursts/team_web/S190828j/web/source_public.html

S. Torii (Waseda U) A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU), 
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka, S. Ozawa (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U),
N. Cannady (GSFC/UMBC),  M. L. Cherry (LSU), 
S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena),
and the CALET collaboration:


The CALET Gamma-ray Burst Monitor (CGBM) was operating at the trigger 
time of S190828j T0 = 2019-08-28 06:34:05.756 UT (The LIGO
Scientific Collaboration and Virgo Collaboration, GCN Circ. 25497
Loading...
 
 ).

No CGBM on-board trigger occurred around the event time.  Based
on the LIGO-Virgo localization sky map, the summed LIGO probabilities 
inside the CGBM HXM (7 - 3000 keV) and SGM (40 keV - 28 MeV) fields 
of view are both 42 % (and 42 % credible region of the updated localization 
map was above the horizon).  The HXM and SGM fields of view were 
centered at RA = 5.4 deg, Dec = 18.4 deg and RA = 13.9 deg, 
Dec = 12.7 deg at T0, respectively.

Based on the analysis of the light curve data with 0.125 sec
time resolution from T0-60 sec to T0+60 sec, we found no
significant excess (signal-to-noise ratio >= 7) around the trigger
time in either the HXM or the SGM data.

The CALET Calorimeter (CAL) was operating in the high energy
trigger mode at the trigger time of S190828j, but the CAL FOV 
does not have any overlap with the high probability localization region.
The CAL FOV was centered at RA= 13.9 deg, DEC= 12.6 deg at T0.

Margarita Pereyra <mpereyra@astro.unam.mx> (UNAM), Simone Dichiara
(GSFC/UMD), Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra
(UNAM), Diego Gonzalez (UNAM), Alexander Kutyrev (GSFC/UMD), William H. Lee
(UNAM), Eleonora Troja (GSFC/UMD), Gabriele Minervini (INAF/IAPS-Rome)  and
Tanner Wolfram (ASU) report:

We observed LIGO/Virgo S190828j event (Minazzoli et al., GCN #25497
Loading...
 
 ) with
the DDOTI/OAN wide-field imager at the Observatorio Astronomico Nacional on
Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) from 2019-08-28
08:00 to 2019-08-28 11:57 UTC (1.4 to 5.4 hours after the event).

We observed approximately 231 square degrees of the sky, with four
pointings centered on 22:10:13.126 +45:18:17.26, 21:45:30.680 +39:42:01.13,
21:25:37.437 +32:53:21.57 and 21:07:43.518 +24:13:55.90. We obtained about
21, 16, 18 and 86 minutes total exposure on each pointing, respectively.
These regions include about 35% of the 2D probability in the current
BAYESTAR map.

We calibrated our images against the APASS catalog. Our 10-sigma limiting
magnitude are typically between w = 19.2 and w = 19.8.

Comparing our 10-sigma detections against the USNO-B1 catalog, we detect no
uncataloged sources with significant fading.

We thank the staff of the Observatorio Astronomico Nacional in San Pedro
Martir.

-- 
*Dr. Margarita Pereyra *

*FFTF, Schlumberger Foundation Alumnae*
----------------------------------------------------------------------------------------------------------------

*Catedr��tico Conacyt*

*Instituto de Astronom��a de la UNAM,*

*Km. 107 Carretera Tijua**na-Ensenada, *

*Ensenada Baja California, M��xico. C.P. 22860*

Oficina: 405

Skype: margarita-pereyra

S. Antier (APC), C. Lachaud (APC), N. Christensen (Artemis), B. Gendre 
(OzGrav-UWA), N. Ismayilov (SHAO), M. Boer (Artemis), L. Eymar 
(Artemis), A. Klotz (IRAP), K. Noysen (Artemis, IRAP), S. Basa (LAM), D. 
Corre (LAL), M. Coughlin (Caltech), D. Coward (OzGrav-UWA), J.G. Ducoin 
(LAL), P. Hello (LAL), N. Leroy (LAL), D. Turpin (NAOC), X. Wang (THU)
report on behalf of the TAROT network and GRANDMA collaborations.

We performed tiled observations of the LIGO/Virgo event S190828j with 
the TAROT-Chili (TCH), TAROT-Calern (TCA) and TAROT-Reunion (TRE) 
telescopes  operating in the visible located respectively at La Silla 
ESO observatory (LaS/ESO), the Calern site at the Cote d'Azur 
Observatory and Les Makes astronomical observatory.

The observation started for TCH on 08/28/19 07:05:39 UTC which 
corresponds approximately to 32 minutes after the GW trigger time.

We performed the following tiled observations :

+-------+------------+------------+---------+---------+---------+
| Tele  | TStart     | TEnd       | RA      | DEC     |   Proba |
| scope | [UTC]      | [UTC]      | [deg]   | [deg]   |     [%] |
|-------+------------+------------+---------+---------+---------|
|  TCH  | 2019-08-28 | 2019-08-30 | 312.95  | 12.768  |     0.1 |
|       | 07:05:39   | 03:48:14   |         |         |         |
|  TCH  | 2019-08-28 | 2019-08-30 | 309.933 | 9.05    |     0.1 |
|       | 07:34:47   | 03:55:02   |         |         |         |
|  TCH  | 2019-08-29 | 2019-08-30 | 314.525 | 27.707  |     0.1 |
|       | 00:24:53   | 01:31:01   |         |         |         |
|  TCH  | 2019-08-29 | 2019-08-30 | 319.388 | 21.777  |    <0.1 |
|       | 03:00:41   | 06:37:09   |         |         |         |
|  TCH  | 2019-08-29 | 2019-08-30 | 314.558 | 13.161  |    <0.1 |
|       | 03:07:29   | 06:43:58   |         |         |         |
|  TCH  | 2019-08-30 | 2019-08-30 | 213.626 | -61.777 |     0.2 |
|       | 03:34:54   | 03:41:24   |         |         |         |
|-------+------------+------------+---------+---------+---------|
|  TCA  | 2019-08-28 | 2019-08-28 | 330.312 | 44.558  |     1.1 |
|       | 19:04:46   | 19:11:17   |         |         |         |
|  TCA  | 2019-08-28 | 2019-08-29 | 331.832 | 46.414  |     0.9 |
|       | 19:11:36   | 20:17:45   |         |         |         |
|  TCA  | 2019-08-28 | 2019-08-30 | 328.674 | 42.703  |     0.8 |
|       | 19:18:25   | 01:24:18   |         |         |         |
|  TCA  | 2019-08-28 | 2019-08-28 | 8.45    | 61.259  |     0.7 |
|       | 19:50:08   | 19:56:38   |         |         |         |
|  TCA  | 2019-08-28 | 2019-08-29 | 334.479 | 46.414  |     0.7 |
|       | 19:56:57   | 01:03:10   |         |         |         |
|  TCA  | 2019-08-28 | 2019-08-29 | 343.245 | 51.981  |     0.6 |
|       | 20:03:48   | 21:09:42   |         |         |         |
|  TCA  | 2019-08-28 | 2019-08-29 | 324.708 | 39.897  |     0.5 |
|       | 20:54:56   | 19:32:34   |         |         |         |
|  TCA  | 2019-08-28 | 2019-08-29 | 12.818  | 63.115  |     0.5 |
|       | 21:01:45   | 02:08:44   |         |         |         |
|  TCA  | 2019-08-28 | 2019-08-28 | 342.488 | 53.837  |     0.4 |
|       | 21:08:35   | 21:15:05   |         |         |         |
|  TCA  | 2019-08-28 | 2019-08-30 | 12.2    | 61.259  |     0.8 |
|       | 22:00:42   | 01:37:59   |         |         |         |
|  TCA  | 2019-08-28 | 2019-08-29 | 327.125 | 40.372  |     0.8 |
|       | 22:07:32   | 23:14:25   |         |         |         |
|  TCA  | 2019-08-28 | 2019-08-28 | 331.157 | 42.703  |     0.7 |
|       | 22:14:21   | 22:20:50   |         |         |         |
|  TCA  | 2019-08-28 | 2019-08-28 | 336.404 | 48.27   |     0.5 |
|       | 22:59:06   | 23:05:36   |         |         |         |
|  TCA  | 2019-08-28 | 2019-08-29 | 333.677 | 48.27   |     0.5 |
|       | 23:05:56   | 19:12:05   |         |         |         |
|  TCA  | 2019-08-28 | 2019-08-29 | 329.541 | 40.847  |     0.5 |
|       | 23:12:46   | 19:18:54   |         |         |         |
|  TCA  | 2019-08-28 | 2019-08-29 | 341.108 | 50.125  |     0.5 |
|       | 23:19:36   | 19:25:44   |         |         |         |
|  TCA  | 2019-08-29 | 2019-08-30 | 332.865 | 44.558  |     0.8 |
|       | 00:24:58   | 01:31:08   |         |         |         |
|  TCA  | 2019-08-29 | 2019-08-30 | 345.565 | 53.837  |     0.6 |
|       | 01:10:19   | 02:16:27   |         |         |         |
|  TCA  | 2019-08-29 | 2019-08-30 | 338.273 | 50.125  |     0.6 |
|       | 01:17:10   | 02:23:17   |         |         |         |
|-------+------------+------------+---------+---------+---------|
|  TRE  | 2019-08-28 | 2019-08-28 | 324     | 36.818  |     3.6 |
|       | 21:35:08   | 21:41:42   |         |         |         |
|  TRE  | 2019-08-28 | 2019-08-28 | 317.922 | 28.636  |     2.7 |
|       | 21:48:24   | 21:54:58   |         |         |         |
|  TRE  | 2019-08-29 | 2019-08-29 | 312.857 | 16.364  |     1.3 |
|       | 15:43:28   | 15:49:56   |         |         |         |
|  TRE  | 2019-08-29 | 2019-08-29 | 309.767 | 12.273  |     0.6 |
|       | 16:15:23   | 16:21:51   |         |         |         |
|  TRE  | 2019-08-29 | 2019-08-29 | 321.081 | 32.727  |     3.3 |
|       | 20:11:45   | 20:18:19   |         |         |         |
|  TRE  | 2019-08-29 | 2019-08-29 | 315     | 24.545  |     1.8 |
|       | 20:24:55   | 20:31:29   |         |         |         |
|  TRE  | 2019-08-29 | 2019-08-29 | 325.946 | 32.727  |     0.7 |
|       | 20:56:14   | 21:02:42   |         |         |         |
+-------+------------+------------+---------+---------+---------+

TStart and TEnd refer respectively to the time of the first and last 
exposure for a given tile. Observations are not necessarily continuous 
in this interval. The Probability refers to the 2D spatial probability 
of the GW skymap enclosed in a given tile. Each tile is 1.9x1.9 degrees 
for TCA and TCH and 4.2x4.2 degrees for TRE. The coordinating 
observations cover about 26% of the cumulative probability of the 
bayestar skymap available on Aug 28, 2019 07:36:47 UTC. The typical 
limiting magnitude is 18.0 for a 60.0 s exposure for TCH and TCA and 
17.0 for a 60.0 s exposure for TRE.

The coverage map is available at:
https://grandma-owncloud.lal.in2p3.fr/index.php/s/tG92ASJWw5C1tWV

No significant transient candidates were found during our low latency 
analysis.

GRANDMA (Global Rapid Advanced Network Devoted to the Multi-messenger 
Addicts) is a network of robotic telescopes connected all over the 
world with both photometry and spectrometry capabilities for Time-domain 
Astronomy (https://grandma.lal.in2p3.fr/). Details on the TAROT 
telescopes  are available on the GRANDMA web pages or on
http://tarot.obs-hp.fr/.

J. Y. Wei (NAOC), X. H. Han (NAOC), N. Dagoneau (CEA/AIM), J. Wang (GXU),
N. Leroy (CNRS/LAL)

on behalf of the SVOM Multi Messenger Astronomy and GWAC teams:
http://www.svom.fr/en/svom-mma-and-gwac-team

We observed 9 sky regions (total: 1350 square degrees with overlaps)
to cover the skymap of the advanced LIGO/Virgo trigger S190828j,
with SVOM/GWAC, at Xinglong Observatory equipped with a set of two
types of wide angle cameras: FFOV cameras (FOV~900 square degrees/camera,
aperture = 3.5 cm) and JFOV cameras (FOV~150 square degrees/camera,
aperture = 18 cm). SVOM/GWAC currently comprises 4 FFOV cameras and
16 JFOV cameras, working with unfiltered band. The observations are
operated in time-series mode, taking one exposure every 25 seconds
(20s exposure + 5s readout). We estimate a 19.6% prior probability
that the 9 observed and processed regions contain the true location of
the source. The images were taken between ~5.5 hours and ~13 hours after
the event trigger time.

The coordinates of the 9 sky regions and observation times are listed
below:

No. Ra �Dec start-obs(UTC) �end-obs(UTC) ���Camera_TYPE

1 01:43:32.26 64:07:03.00 2019-08-28 13:53:25 2019-08-28 16:51:08 JFOV
2 00:07:40.03 51:45:14.40 2019-08-28 16:41:24 2019-08-28 16:44:15 JFOV
3 00:13:04.03 64:02:39.84 2019-08-28 17:05:25 2019-08-28 17:22:48 JFOV
4 21:27:48.00 47:17:53.52 2019-08-28 13:03:27 2019-08-28 13:05:53 JFOV
5 20:43:28.32 -1:13:58.98 2019-08-28 13:20:46 2019-08-28 13:35:19 JFOV
6 21:18:27.60 13:20:15.00 2019-08-28 16:08:33 2019-08-28 16:19:54 JFOV
7 20:50:18.72 63:41:09.96 2019-08-28 13:30:52 2019-08-28 13:35:43 JFOV
8 21:59:13.44 48:02:44.52 2019-08-28 13:40:52 2019-08-28 14:06:20 JFOV
9 22:05:10.08 34:10:09.48 2019-08-28 12:08:19 2019-08-28 19:00:58 JFOV

The sky coverage map is available at: 
http://cmm.svom.cn/gwpub/O3/S190828j/S190828j.png 
(user:svomo3 pwd:gwo3)

The weather conditions were hazy during the observations. A 3 sigma 
limiting magnitude of about 16.3 mag in R band was obtained in the single 
frames. No credible new source is detected by our online pipeline during 
follow-up observations. A more detailed image analysis including
co-addition is ongoing with our offline pipeline to search for transient
candidates.

The LIGO Scientific Collaboration and the Virgo Collaboration report:

We have conducted further analysis of the data from LIGO Hanford
Observatory (H1), LIGO Livingston Observatory (L1) and Virgo Observatory
(V1) around the time of the compact binary merger (CBC) candidate S190828j
(GCN Circular 25497
Loading...
 
 ). Parameter estimation has been performed using
LALInference [1] and a new sky map, LALInference.fits.gz, distributed via
GCN Notice, is available for retrieval from the GraceDB event page:

https://gracedb.ligo.org/superevents/S190828j

The preferred sky map at this time is LALInference.fits.gz. The 90%
credible region is 228 deg2. Marginalized over the whole sky, the a
posteriori luminosity distance estimate is 1946 +/- 388 Mpc (a posteriori
mean +/- standard deviation).

For further information about analysis methodology and the contents of this
alert, refer to the LIGO/Virgo Public Alerts User Guide <
https://emfollow.docs.ligo.org/userguide/>.

 [1] Veitch et al. PRD 91, 042003 (2015)