LIGO/Virgo S190923y

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
S190923y
 in a time range of 1000 seconds [3] centered on the alert event time
(2019-09-23 12:47:39.646 UTC to 2019-09-23 13:04:19.646 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 S190923y calculated from the map
circulated in the 2-Initial 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 S190923y ranges from  0.029 to 1.120 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)

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov 
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

H.Levato 
(Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

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




MASTER-Tunka robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the LIGO/Virgo S190923y errorbox  374 sec after notice time and 798 sec after trigger time at 2019-09-23 13:09:17 UT, with upper limit up to  18.5 mag. The observations began at zenit distance = 75 deg. The sun  altitude  is -19.7 deg. 

The galactic latitude b = -60 deg., longitude l = 98 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/ligo_1.php?id=10825

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

     889 | 2019-09-23 13:09:17 |        MASTER-Tunka | (10h 15m 27.073s , +50d 15m 33.84s) |   C |   180 | 18.5 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.

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

The HAWC Collaboration performed a follow-up of the gravitational wave
trigger S190923y. At the time of the trigger the HAWC
local zenith was oriented towards (RA, Dec) = (98.5deg, 19.0deg).
52% 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 0.0deg to 45.0deg for the area searched in this
analysis. The 5sigma detection sensitivity to a 1s (100s) burst in the
80-800GeV energy range goes from 1.2e-06 erg/cm^2 to 1.1e-04 erg/cm^2
(6.4e-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.

The LIGO Scientific Collaboration and the Virgo Collaboration report:

We identified the compact binary merger candidate S190923y during real-time
processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston
Observatory (L1) at 2019-09-23 12:55:59.646 UTC (GPS time: 1253278577.646).
The candidate was found by the PyCBC Live [1], MBTAOnline [2], and GstLAL
[3] analysis pipelines.

S190923y is an event of interest because its false alarm rate, as estimated
by the online analysis, is 4.8e-08 Hz, or about one in 7 months. The
event's properties can be found at this URL:

https://gracedb.ligo.org/superevents/S190923y

The classification of the GW signal, in order of descending probability, is
NSBH (68%), Terrestrial (32%), BNS (<1%), BBH (<1%), or MassGap (<1%).

Assuming the candidate is astrophysical in origin, there is strong evidence
for the lighter compact object having a mass < 3 solar masses (HasNS:
>99%). 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 [4],
distributed via GCN notice about 6 minutes after the candidate

For the bayestar.fits.gz sky map, the 90% credible region is 2107 deg2.
Marginalized over the whole sky, the a posteriori luminosity distance
estimate is 438 +/- 133 Mpc (a posteriori mean +/- standard deviation).

The Virgo (V1) detector was not in observing mode at the time of the
candidate but was collecting low-noise data during a tuning of the
interferometer working point.  We are investigating whether the V1 data can
be used in parameter estimation analyses.

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] Nitz et al. PRD 98, 024050 (2018)

 [2] Adams et al. CQG 33, 175012 (2016)

 [3] Messick et al. PRD 95, 042001 (2017)

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

Francesca Onori, Antonio Martin-Carrillo
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 S190923y (GCN 25814
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 ).

At the time of the event (2019-09-23 12:55:59 UTC, hereafter T0),
INTEGRAL was operating in nominal mode. The peak of the event
localization probability was at an angle of 157 deg with respect to
the spacecraft pointing axis. This orientation implies strongly
suppressed (3% of optimal) response of ISGRI, somewhat suppressed (62%
of optimal) response of IBIS/Veto, and somewhat suppresse d (43% of
optimal) response of SPI-ACS.

The background within +/-300 seconds around the event was very stable
(excess variance 1.1).

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 3.4e-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 ~3.4e-07 (6.7e-08)
erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range.

For the mean reported distance 438.0 Mpc this corresponds to the limit
on the tot al isotropic equivalent energy in 1 s of 7.9e+48 erg for
the short GRB spectrum and for a long GRB spectrum isotropic
equivalent luminosity in 1 s (8 s) of 4e+48 erg/s (1.5e+48 erg/s)

We report for completeness and in order of FAP, all excesses
identified in the search region. We find: 6 likely background
excesses:

scale | T | S/N | luminosity ( x 1e+49 erg/s) | FAP
1.7 | -41.9 | 4.4 | 8.61 +/- 2.55 +/- 5.68 | 0.0534
1.6 | -60.1 | 4.1 | 8.38 +/- 2.63 +/- 5.53 | 0.109
2.55 | 131 | 3.4 | 5.54 +/- 2.08 +/- 3.66 | 0.424
1 | 92 | 3.7 | 9.32 +/- 3.32 +/- 6.15 | 0.456
3.75 | -93.8 | 3 | 3.9 +/- 1.71 +/- 2.58 | 0.581
0.05 | -2.35 | 3.2 | 3.73 +/- 1.51 +/- 2.46 | 0.635

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.

Part of the probability region was serendipitously observed
by INTEGRAL FoV instruments (IBIS, JEM-X), analysis is ongoing.
There was not ISGRI / IBIS detection at the time of the event, indicating
absence
of strong counterpart in IBIS.

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
-- 
Dr. Francesca Onori
Postdoctoral Researcher
IAPS, via Fosso del Cavaliere, 100, 00133 - Rome, Italy
e-mail: francesca.onori@inaf.it
Tel: +39 06 45488128

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 S190923y event using the 90% contour of the Initial bayestar probability
map provided by the GW interferometers (GCN#25814
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  <https://gcn.gsfc.nasa.gov/gcn3/25814.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/S190923y_Initial.png <http://antares.in2p3.fr/GW/S190923y_Initial.png>.
Considering the location probability provided by the LIGO/Virgo collaborations, there is a
41.7% 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 2019-09-23 12:55:59 and in the 90% contour of the S190923y
event. The expected number of atmospheric background events in the region visible by ANTARES is
6.99e-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 5.03e-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.

H. Negoro (Nihon U.), S. Sugita, M. Serino (AGU), N. Kawai (Tokyo Tech), 
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), M. Sugizaki (NAOC) 
report on behalf of the MAXI team: 

We examined MAXI/GSC all-sky X-ray images (2-20 keV) 
after the LVC trigger S190923y at 2019-09-23 12:55:59.645 UTC (GCN 25814
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 ). 

At the trigger time of S190923y, the high-voltage of MAXI/GSC was on. 
The instantaneous field of view of GSC at the GW trigger time covered 3% 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 90% 
of the 90% credible region of the bayestar skymap from 12:55:59 to 14:27:58 UTC (T0+0 to T0+5519 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.

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

In response to the LIGO/Virgo GW event S190923y at T0 = 2019-09-23
12:55:59.646 (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 60% of the S190923y 90% c.l. localization region (LR) 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 S190923y LR, from a minimum of 1.08E-06 erg cm^-2 to a maximum
of 7.70E-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.

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

In response to the LIGO-Virgo GW event S190923y at T0 = 2019-09-23
12:55:59.646 UTC a preliminary analysis of the AGILE exposure at T0
shows that the Gamma-Ray Imaging Detector (GRID) exposure covered the 10%
of the 90% c.l. localization region (LR) (40% of 90% c.l. localization
region (LR) is occulted by Earth) at an off-axis angle of about 5
degrees.

We performed an analysis of the GRID data in the energy range 50 MeV -
10 GeV on T0, where good exposure of the S190923y 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 7.0e-07 to 9.3e-07 erg cm^-2 s^-1, with exposure of about 10% of
the LR over the time interval ( T0 - 2s ; T0 + 2s );
- from 2.9e-07 to 4.2e-07 erg cm^-2 s^-1, with exposure of about 10% of
the LR over the time interval ( T0 ; T0 + 10s );
- from 6.5e-08 to 6.6e-06 erg cm^-2 s^-1, with exposure of about 11% of
the LR over the time interval ( T0 ; 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/AGILE_FOV_LIGO-VirgoS190923y_1909232521

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



==========================================================================
Francesco Verrecchia
ASDC - ASI Science Data Center -
INAF/OAR - Istituto Nazionale di Astrofisica/
           Osservatorio Astronomico di Roma -

c/o ASI - Agenzia Spaziale Italiana -
via del Politecnico snc, I-00133, Roma  - Italy
==========================================================================
e-mail:francesco.verrecchia@ssdc.asi.it
phone:+39 068567 882
e-mail OAR:francesco.verrecchia@oa-roma.inaf.it
==========================================================================

B. Mailyan (UAH) and J. Wood (NASA) report on behalf of the Fermi-GBM Team
and the GBM-LIGO/Virgo group

For S190923y and using the initial bayestar skymap, Fermi-GBM was observing
42.3% 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 S190923y (GCN 25814
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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 for the LVC
localization region visible to Fermi at merger time.
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, weighted by GW localization probability
(in units of 10^-7 erg/s/cm^2):

Timescale  soft     norm     hard
--------------------------------------
0.128 s:     2.2       4.1       8.8
1.024 s:     0.74     1.3       2.4
8.192 s:     0.26     0.4       0.79

Assuming the median luminosity distance of 438 Mpc from the GW detection,
we estimate the following intrinsic luminosity upper limits over
the 1 keV-10 MeV energy range (in units of 10^48 erg/s):

Timescale  Soft     Normal   Hard
------------------------------------
0.128s:      9.4         16.2     57.4
1.024s:      3.2          5.1      15.6
8.192s:      1.1         1.6       5.2

Antonio Martin-Carrillo (UCD), Francesca Onori, 
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

At the time of the event S190923y (2019-09-23 12:55:59 UTC, GCN 25814
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 ) and based on the initial localization map, 8% of the LIGO/Virgo GW localization was within the field of view of IBIS. The background within +/-300 seconds around the event was very stable (excess variance 1.1).

Initial analysis of the pointed observations of IBIS do not reveal any relevant counterparts at this point. 3-sigma upper limits of about 5e-10erg/cm2/s (28-40 keV energy range) in single pointings of about 30 min at ~T0+5.5h have been found in areas at the edge of the 90% LIGO/Virgo contour. 

INTEGRAL will continue to serendipitously observe the localization area
of S190923y over the nex few hours. Any relevant candidates will be reported separately.

We have included this new data to the initial results presented in Onori et al (GCN 25815
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 ) to search for any impulsive events in INTEGRAL SPI-
ACS (as described in [1]), IBIS, and IBIS/Veto data.

We do not detect any significant counterparts and estimate a 3-sigma
upper limit on the 75-2000 keV fluence of 3.4e-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 ~3.4e-07 (3.7e-08)
erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range.

For the mean reported distance 438.0 Mpc this corresponds to the limit
on the total isotropic equivalent energy in 1 s of 7.8e+48 erg for
the short GRB spectrum and for a long GRB spectrum isotropic
equivalent luminosity in 1 s (8 s) of 2.6e+48 erg/s (8.6e+47 erg/s)

These upper limits take into account that the peak of the event
localization probability was at an angle of 158 deg with respect to
the spacecraft pointing axis at the time of the trigger. 
This orientation implies strongly
suppressed (3.2% of optimal) response of ISGRI, somewhat suppressed
(62% of optimal) response of IBIS/Veto, and somewhat suppressed (43%
of optimal) response of SPI-ACS.


All results quoted are preliminary.
This circular is an official product of the INTEGRAL Multi-Messenger
team.

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

A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU), 
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka, S. Torii (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 S190923y T0 = 2019-09-23 12:55:59.646 UT (The
LIGO Scientific Collaboration and Virgo Collaboration, GCN Circ.
25814
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 ).

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 40 % and 55 %, respectively (and 68 % credible region 
of the initial sky map was above the horizon).  The HXM and  SGM 
fields of view were centered at RA = 62.7 deg, Dec = 4.2 deg and 
RA = 55.3 deg, Dec = -2.5 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 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 S190923y. Using the 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 in the 
overwrap region with the LIGO-Virgo high probability localization
region.  The 90% upper limit of CAL is 1.2x10^-5 erg/cm^2/s 
(10-100 GeV) when the summed LIGO-Virgo probability reaches 10%.
The CAL FOV was centered at RA= 55.3 deg, DEC= -2.5 deg at T0.

F. Longo (Univ. and INFN Trieste), E. Bissaldi (Politecnico and INFN Bari), E. Moretti (IFAE, Barcelona), M. Moss (George Washington Univ.), N. Omodei (Stanford Univ.), D. Kocevski (NASA/MSFC) and M. Axelsson (KTH and Stockholm Univ.) report on behalf of the Fermi-LAT Collaboration:

We have searched data collected by the Fermi Large Area Telescope (LAT) on Sep 23, 2019, for possible high-energy (E > 100 MeV) gamma-ray emission in spatial/temporal coincidence with the LIGO/Virgo trigger S190923y (GCN 25814
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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 time, and "cumulative coverage" as the integral of the instantaneous coverage over time. Fermi-LAT had an instantaneous coverage of ~40% of the LIGO probability region at the time of the trigger (T0 = 2019-09-23 12:55:59.646 UTC) and reached 100% cumulative coverage at approximately T0 + 8.8 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 1.3e-10 and 1.4e-9 [erg/cm^2/s].

The Fermi-LAT point of contact for this event is Elena Moretti (emoretti@ifae.es). 

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.

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

In response to:
LIGO/Virgo GW trigger S190923y
T0=2019-09-23 12:55:59 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 S190923y as well as in a 24 hr time
interval following the event.

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 PARTIALLY COINCIDENT (68.2%) with
the LIGO/Virgo 90% localization region (bayestar.fits.gz,0)
at the time T0 of the merger alert, achieving TOTAL OVERLAP
at approximately T0+1.36 hours.

-------
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
https://arxiv.org/abs/1906.07422
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T. Sakamoto (AGU), S. D. Barthelmy (NASA/GSFC),
A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL),
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),
N. Klingler (PSU), H. A. Krimm (NSF),
N. P. M. Kuin (UCL-MSSL), 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 (Toronto),
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 S190923y (LIGO/VIRGO Collaboration GCN Circ. 25814
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 ),
where T0 is the LVC trigger time (2019-09-23T12:55:59.645 UTC).

The center of the BAT field of view (FOV) at T0 is
RA = 5.951 deg,
DEC = -1.780 deg,
and the roll angle is 107.879 deg.
The BAT FOV (>10% partial coding) covers 0.00% of the integrated
LVC localization probability, and 0.00% of the galaxy convolved
probability (Evans et al. 2016). Note that the sensitivity in the BAT FOV
changes with the partial coding fraction. Please see the BAT FOV figure
in the summary page (link below) for the specific location of the LVC
region relative to the BAT FOV.

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 ~ 7.56 x 10^-8 erg/s/cm^2.
Assuming a luminosity of ~ 2 x 10^47 erg/s (similar to GW170817)
and an average Epeak of ~ 400 keV for short GRBs (Bhat et al. 2016),
this flux upper limit corresponds to a distance of ~ 82.64 Mpc.

Event data are available from T0-101.32 to T+98.757. No significant
detections are found in the 15-350 keV images created using intervals of
T0 to T0+0.1 s, T0-2 s to T0+8 s, and the whole event data range.

BAT retains decreased, but significant, sensitivity to rate increases for
gamma-ray events outside of its FOV. About 99.92% 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/S190923y/web/source_public.html

D. Turpin (NAOC), P. Hello (LAL), K. Noysena (Artemis, IRAP), 
C. Thoene (HETH/IAA-CSIC), M. Boer (Artemis), N. Christensen (Artemis), 
L. Eymar (Artemis), A. Klotz (IRAP), S. Antier (APC), S. Basa (LAM), 
D. Corre (LAL), M. Coughlin (Caltech), D. Coward (OzGrav-UWA), J.G. 
Ducoin (LAL), B. Gendre (OzGrav-UWA), D. A. Kann (HETH/IAA-CSIC), 
C. Lachaud (APC), N. Leroy (LAL) report on behalf of the TAROT 
network and GRANDMA collaborations:

We performed tiled observations of the LIGO/Virgo S190923y event with the 
TAROT-Reunion (TRE), TAROT-Calern (TCA) and TAROT-Chili (TCH) telescopes
operating in the visible located respectively at 
Les Makes astronomical observatory, the Cote d'Azur
observatory and La Silla ESO observatory (LaS/ESO).

The observation started on 09/23/19 16:30:12 UTC for TRE which 
corresponds approximately to 215 minutes after the 
GW trigger time. 

For TCA it started on 09/23/19 18:22:31 UTC which corresponds 
approximately to 327 minutes after the GW trigger time.

For TCH it started on 09/23/19 23:42:17 UTC which corresponds 
approximately to 647 minutes after the GW trigger time.

We performed the following tiled observations :
+-------+------------+------------+---------+---------+---------+
| Tele �| TStart � � | TEnd � � � | RA � � �| DEC � � | � Proba |
| scope | [UTC] � � �| [UTC] � � �| [deg] � | [deg] � | � � [%] |
|-------|------------+------------+---------+---------+---------|
| �TRE �| 2019-09-23 | 2019-09-25 | 250.909 | -40.909 | � � 1.2 |
| � � � | 16:30:12 � | 18:18:14 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-23 | 2019-09-25 | 243.243 | -32.727 | � � 1.1 |
| � � � | 16:43:24 � | 16:01:15 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-23 | 2019-09-25 | 243.117 | -28.636 | � � 1.1 |
| � � � | 16:55:50 � | 16:13:27 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-23 | 2019-09-25 | 245.455 | -40.909 | � � 1 � |
| � � � | 17:08:55 � | 16:26:45 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-23 | 2019-09-25 | 285 � � | -73.636 | � � 0.8 |
| � � � | 17:21:15 � | 19:09:01 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-23 | 2019-09-25 | 243 � � | -24.545 | � � 0.8 |
| � � � | 17:40:29 � | 16:58:26 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-23 | 2019-09-25 | 256.154 | -53.182 | � � 1.6 |
| � � � | 17:56:56 � | 17:33:16 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-23 | 2019-09-25 | 249.677 | -45 � � | � � 1.5 |
| � � � | 18:16:07 � | 17:52:26 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-23 | 2019-09-25 | 246.857 | -36.818 | � � 1.4 |
| � � � | 18:29:19 � | 18:05:44 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-23 | 2019-09-25 | 276 � � | -69.545 | � � 1 � |
| � � � | 19:13:36 � | 21:19:48 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-23 | 2019-09-25 | 265.714 | -61.364 | � � 1.2 |
| � � � | 21:05:15 � | 20:41:36 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-23 | 2019-09-25 | 270 � � | -65.455 | � � 1.2 |
| � � � | 21:17:59 � | 20:54:39 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-23 | 2019-09-25 | 90 � � �| 4.091 � | � � 1.1 |
| � � � | 21:35:17 � | 23:37:06 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-23 | 2019-09-26 | 85.909 �| 0 � � � | � � 1 � |
| � � � | 21:56:18 � | 00:02:43 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-23 | 2019-09-25 | 85.909 �| 4.091 � | � � 0.8 |
| � � � | 22:15:29 � | 21:51:45 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-23 | 2019-09-25 | 91.034 �| 8.182 � | � � 1.5 |
| � � � | 23:09:44 � | 22:46:17 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-24 | 2019-09-24 | 248.108 | -32.727 | � � 0.7 |
| � � � | 18:28:15 � | 18:34:32 � | � � � � | � � � � | � � � � |
| �TRE �| 2019-09-24 | 2019-09-25 | 260.425 | -57.273 | � � 1.4 |
| � � � | 19:22:29 � | 20:24:29 � | � � � � | � � � � | � � � � |
|-------|------------+------------+---------+---------+---------|
| �TCA �| 2019-09-23 | 2019-09-25 | 150.95 �| 48.27 � | � � 0.1 |
| � � � | 18:22:31 � | 02:58:48 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-23 | 2019-09-25 | 89.075 �| 11.156 �| � � 0.1 |
| � � � | 23:41:57 � | 03:19:06 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-24 | 2019-09-24 | 81.575 �| -9.256 �| � � 0.1 |
| � � � | 00:27:20 � | 03:03:58 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-24 | 2019-09-24 | 80.112 �| -11.112 | � � 0.1 |
| � � � | 00:40:21 � | 00:46:41 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-24 | 2019-09-26 | 79.7 � �| -9.256 �| � � 0.1 |
| � � � | 00:47:07 � | 00:23:08 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-24 | 2019-09-26 | 92.783 �| 3.733 � | � � 0.1 |
| � � � | 00:53:52 � | 00:29:56 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-24 | 2019-09-25 | 146.538 | 46.414 �| � � 0.2 |
| � � � | 01:26:35 � | 02:32:55 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-24 | 2019-09-25 | 149.185 | 46.414 �| � � 0.2 |
| � � � | 01:33:22 � | 02:35:21 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-24 | 2019-09-25 | 151.832 | 46.414 �| � � 0.2 |
| � � � | 01:40:06 � | 02:46:24 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-24 | 2019-09-25 | 148.223 | 48.27 � | � � 0.1 |
| � � � | 01:59:17 � | 03:05:36 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-24 | 2019-09-25 | 145.495 | 48.27 � | � � 0.1 |
| � � � | 02:06:01 � | 03:12:21 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-24 | 2019-09-24 | 142.768 | 48.27 � | � � 0.1 |
| � � � | 02:18:25 � | 02:24:45 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-24 | 2019-09-25 | 153.677 | 48.27 � | � � 0.1 |
| � � � | 02:25:12 � | 18:31:12 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-24 | 2019-09-25 | 156.405 | 48.27 � | � � 0.1 |
| � � � | 02:31:57 � | 18:38:00 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-24 | 2019-09-25 | 83.022 �| -7.401 �| � � 0.1 |
| � � � | 02:38:42 � | 01:14:45 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-24 | 2019-09-25 | 159.132 | 48.27 � | � � 0.1 |
| � � � | 02:50:52 � | 18:57:10 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-24 | 2019-09-25 | 147.433 | 42.703 �| � � 0.1 |
| � � � | 03:04:26 � | 04:08:35 � | � � � � | � � � � | � � � � |
| �TCA �| 2019-09-24 | 2019-09-25 | 161.859 | 48.27 � | � � 0.1 |
| � � � | 03:30:18 � | 02:06:41 � | � � � � | � � � � | � � � � |
|-------+------------+------------+---------+---------+---------+
| �TCH �| 2019-09-23 | 2019-09-25 | 261.239 | -54.505 | � � 0.2 |
| � � � | 23:42:17 � | 03:18:23 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-24 | 2019-09-25 | 251.119 | -52.686 | � � 0.2 |
| � � � | 00:03:52 � | 23:38:03 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-24 | 2019-09-25 | 243.214 | -36.323 | � � 0.2 |
| � � � | 00:08:26 � | 23:44:47 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-24 | 2019-09-26 | 265.656 | -69.05 �| � � 0.1 |
| � � � | 00:34:28 � | 00:10:43 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-24 | 2019-09-25 | 239.646 | -21.777 | � � 0.2 |
| � � � | 02:05:45 � | 00:41:50 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-24 | 2019-09-25 | 239.014 | -19.959 | � � 0.2 |
| � � � | 02:24:51 � | 01:01:21 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-24 | 2019-09-25 | 285.466 | -70.868 | � � 0.2 |
| � � � | 02:50:54 � | 23:57:11 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-24 | 2019-09-26 | 296.15 �| -74.505 | � � 0.1 |
| � � � | 03:29:45 � | 00:36:07 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-24 | 2019-09-25 | 265.656 | -58.141 | � � 0.2 |
| � � � | 05:14:24 � | 06:20:43 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-24 | 2019-09-25 | 93.211 �| 5.495 � | � � 0.2 |
| � � � | 05:53:19 � | 06:59:50 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-24 | 2019-09-25 | 92.787 �| 10.95 � | � � 0.4 |
| � � � | 06:26:33 � | 07:32:51 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-24 | 2019-09-25 | 94.624 �| 10.95 � | � � 0.4 |
| � � � | 06:33:19 � | 07:39:36 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-24 | 2019-09-25 | 90.95 � | 10.95 � | � � 0.3 |
| � � � | 06:40:04 � | 07:46:20 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-24 | 2019-09-25 | 94.148 �| 9.132 � | � � 0.3 |
| � � � | 06:46:48 � | 07:53:05 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-24 | 2019-09-25 | 96.46 � | 10.95 � | � � 0.2 |
| � � � | 07:01:09 � | 08:05:28 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-24 | 2019-09-25 | 94.07 � | 7.314 � | � � 0.2 |
| � � � | 07:18:38 � | 08:24:58 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-25 | 2019-09-26 | 239.793 | -27.707 | � � 0.2 |
| � � � | 01:27:40 � | 00:03:57 � | � � � � | � � � � | � � � � |
| �TCH �| 2019-09-25 | 2019-09-25 | 242.134 | -21.777 | � � 0.1 |
| � � � | 01:46:49 � | 01:53:08 � | � � � � | � � � � | � � � � |
|-------+------------+------------+---------+---------+---------+
TStart and TEnd refers 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 TRE tile is 4.2x4.2 degrees and 1.9x1.9 degrees for TCA and TCH. 
These observations cover about 25.5% the cumulative probability of the
Bayestar skymap available on Sep 23, 2019 13:01:56 UTC.
The typical limiting magnitude is 17.0 and 18.0 for a 60.0 s exposure
for TRE and TCA/TCH, respectively.

The coverage map is available at: 
https://grandma-owncloud.lal.in2p3.fr/index.php/s/Y2sXYjRmkubuRrw

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 spectroscopy capabilities for Time-
domain Astronomy (https://grandma.lal.in2p3.fr/).
Details on the TRE, TCA and TCH telescopes are available on the GRANDMA 
web pages or on �http://tarot.obs-hp.fr/.

This circular is citable.

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tiurina, P.Balanutsa,A.Kuznetsov, V.Vladimirov, D. Vlasenko, I.Gorbunov,D.Zimnukhov,
V.Senik, T.Pogrosheva, K.Pozdnyakov, A.Chasovnikov, V.Topolev, F.Balakin, D.Kuvshinov(Lomonosov Moscow State University, SAI,Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile(Observatorio Astronomico Felix Aguilar OAFA),
H.Levato(Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE),
R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias),
D. Buckley(South African Astronomical Observatory),
O.A. Gres, N.M. Budnev, O.Ershova(Irkutsk State University, API),
A. Tlatov, D. Dormidontov(Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko(Blagoveschensk Educational State University)


MASTER Global Robotic Net started LIGO/Virgo S190923y (Minazzoli et al. LVC GCN 25814
Loading...
 
 , Ttrig = 2019-09-23 12:55:59.646 UT)
inspection 374 sec after notice time (798 sec after trigger time) at 2019-09-23 13:09:17 UT
(Lipunov et al. GCN 25812
Loading...
 
 ) https://master.sai.msu.ru/site/master2/ligo_1.php?id=10825 .


MASTER OT J162250.41-482250.3 discovery

MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L )
discovered OT source at (RA, Dec) = 16h 22m 50.41s -48d 22m 50.3s on 2019-09-26.80632 UT   (AT 2019rfj
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 ).

The OT unfiltered magnitude is 17.0m (mlim=18.6).

The OT is seen on 2 images on 2019-09-26 19:33:10,  19:21:06UT in MASTER-SAAO
and on 4 images on 2019-09-27 00:12:12-00:30:55 in MASTER-OAFA.
  There is no minor planet at this place.

We have reference images on 2019-09-23.89472 UT (nearest in time) with unfiltered mlim=18.2m.

Spectral observations are required.

The discovery and reference images are available at:

http://master.sai.msu.ru/static/OT/162250.41-482250.3.png



The observation and reduction will be continued.
The message may be cited.

David Buckley (South African Astronomical Observatory), Stefano Ciroi (Padova University), Marina Orio (Istituto Nazionale di Astrofisica-Padova, and University of Wisconsin), Saurabh Jah  (Rutgers University) and Joanna Mikolajewska (Nicolaus Copernicus Center of the PAS) report:

 On 2019/9/27 at UT 17:48:22 we obtained an optical spectrum of the transient source MASTER OT J162250.41-482250.3  discovered by the MASTER Global Robotic Net  in the field of the gravitational wave event S190923y (see GCN 25855
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 ) , with the Robert Stobie spectrograph on the SALT telescope and the PG 300 grating, in the 3300-9800 Angstrom range and with a 22 Angstrom spectral resolution.
 The spectrum has a blue continuum and various emission lines, of which the most prominent is H-alpha. Several other emission lines of He I and He at 4686 Angstrom are also detected, and all spectral lines do not show significant red shift. We measured the following equivalent widths:

He II 4686 Angstrom:      0.71 Angstrom
Hbeta                                 0.79  Angstrom
He I 5876  Angstrom      1.02 Angstrom
Halpha                              10.12 Angstrom
He I 6678   Angstrom     1.93 Angstrom
He I 7065   Angstrom     1.73 Angstrom

 The spectrum is consistent with a Galactic source, likely to be a cataclysmic variable or  another low mass binary in outburst. This result rules out that  this transient as the optical counterpart of the gravitational wave event.