LIGO/Virgo S191215w

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
S191215w
 in a time range of 1000 seconds [3] centered on the alert event time
(2019-12-15 22:22:32.333 UTC to 2019-12-15 22:39:12.333 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
S191215w calculated from the map circulated in the 1-Preliminary 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 S191215w ranges from 0.031 to 1.080 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] PoS(ICRC2019)918 and 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-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) started inspect of the LIGO/Virgo S191215w errorbox  145 sec after trigger time at 2019-12-15 22:33:17 UT, with upper limit up to  18.3 mag. The observations began at zenith distance = 35 deg. The sun  altitude  is -34.7 deg. 

MASTER-IAC robotic telescope  located in Spain (IAC Teide Observatory) started inspect of the LIGO/Virgo S191215w errorbox  217 sec after trigger time at 2019-12-15 22:34:29 UT, with upper limit up to  17.8 mag. The observations began at zenith distance = 64 deg. The sun  altitude  is -57.4 deg. 

MASTER-Kislovodsk robotic telescope  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the LIGO/Virgo S191215w errorbox  535 sec after trigger time at 2019-12-15 22:39:47 UT, with upper limit up to  16.9 mag. The observations began at zenith distance = 80 deg. The sun  altitude  is -62.4 deg. 

The galactic latitude b = -23 deg., longitude l = 81 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/ligo_1.php?id=11055

We obtain a following upper limits.  

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

     236 | 2019-12-15 22:33:17 |         MASTER-SAAO | (06h 43m 57.53s , -01d 50m 41.4s) |   C |   180 | 18.3 |        
     307 | 2019-12-15 22:34:29 |          MASTER-IAC | (06h 46m 39.84s , -07d 56m 55.9s) |   C |   180 | 17.5 |        
     307 | 2019-12-15 22:34:29 |          MASTER-IAC | (06h 38m 28.61s , -07d 53m 21.7s) |   C |   180 | 17.4 |        
     454 | 2019-12-15 22:36:56 |         MASTER-SAAO | (06h 37m 52.59s , -05d 49m 28.9s) |   C |   180 | 18.1 |        
     572 | 2019-12-15 22:38:53 |          MASTER-IAC | (06h 46m 47.24s , -07d 58m 00.9s) |   C |   180 | 15.1 |        
     572 | 2019-12-15 22:38:53 |          MASTER-IAC | (06h 38m 35.78s , -07d 54m 24.1s) |   C |   180 | 14.5 |        
     591 | 2019-12-15 22:39:47 |   MASTER-Kislovodsk | (07h 09m 49.75s , -37d 13m 51.5s) |   C |   110 | 16.8 |        
     591 | 2019-12-15 22:39:47 |   MASTER-Kislovodsk | (07h 20m 00.97s , -37d 41m 14.4s) |   C |   110 | 16.6 |        
     619 | 2019-12-15 22:40:16 |         MASTER-SAAO | (07h 47m 32.27s , -43d 41m 11.5s) |   C |   110 | 18.2 |        
     699 | 2019-12-15 22:41:26 |          MASTER-IAC | (21h 57m 03.70s , +24d 59m 33.6s) |  P| |   130 | 17.5 |        
     699 | 2019-12-15 22:41:26 |          MASTER-IAC | (21h 56m 21.60s , +25d 03m 16.3s) |  P- |   130 | 17.0 |        
     731 | 2019-12-15 22:41:58 |   MASTER-Kislovodsk | (07h 09m 46.15s , -37d 13m 58.0s) |   C |   130 | 16.9 |        
     731 | 2019-12-15 22:41:58 |   MASTER-Kislovodsk | (07h 19m 57.20s , -37d 41m 21.8s) |   C |   130 | 16.9 |        
     765 | 2019-12-15 22:42:27 |         MASTER-SAAO | (07h 47m 35.71s , -43d 40m 37.5s) |   C |   140 | 18.3 |        
     904 | 2019-12-15 22:44:36 |          MASTER-IAC | (21h 56m 26.72s , +25d 02m 14.6s) |  P- |   160 | 17.2 |        
     904 | 2019-12-15 22:44:36 |          MASTER-IAC | (21h 57m 08.87s , +24d 58m 34.9s) |  P| |   160 | 17.8 |        
     942 | 2019-12-15 22:45:08 |         MASTER-SAAO | (07h 47m 30.18s , -43d 41m 19.5s) |   C |   170 | 18.2 |        
Filter C is a clear (unfiltred) band. 


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

The LIGO Scientific Collaboration and the Virgo Collaboration report:

We identified the compact binary merger candidate S191215w during
real-time processing of data from LIGO Hanford Observatory (H1), LIGO
Livingston Observatory (L1), and Virgo Observatory (V1) at 2019-12-15
22:30:52.333 UTC (GPS time: 1260484270.333). The candidate was found
by the GstLAL [1], CWB [2], MBTAOnline [3], and PyCBC Live [4]
analysis pipelines.

S191215w is an event of interest because its false alarm rate, as
estimated by the online analysis, is 1e-09 Hz, or about one in 31
years. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S191215w

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, the probability
that the lighter compact object has a mass < 3 solar masses (HasNS) is
<1%. Using the masses and spins inferred from the signal, the
probability of matter outside the final compact object (HasRemnant) is
<1%.

Two sky maps are available at this time and can be retrieved from the
GraceDB event page:
  * bayestar.fits.gz,0, an initial localization generated by BAYESTAR
[5], distributed via GCN notice about 7 minutes after the candidate
event time.
  * bayestar.fits.gz,1, an initial localization generated by BAYESTAR
[5], distributed via GCN notice about 15 minutes after the candidate
event time.

The preferred sky map at this time is bayestar.fits.gz,1. For the
bayestar.fits.gz,1 sky map, the 90% credible region is 923 deg2.
Marginalized over the whole sky, the a posteriori luminosity distance
estimate is 2216 +/- 590 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] Adams et al. CQG 33, 175012 (2016)
  [4] Nitz et al. PRD 98, 024050 (2018)
  [5] Singer & Price PRD 93, 024013 (2016)

Diego Gotz (AIM/DAp CEA Saclay, France), Alexander Lutovinov (IKI, Russia)
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 S191215w (GCN 26441
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 ).

At the time of the event (2019-12-15 22:30:52 UTC, hereafter T0),
INTEGRAL was operating in nominal mode. The peak of the event
localization probability was at an angle of 37 deg with respect to the
spacecraft pointing axis. This orientation implies strongly suppressed
(14% of optimal) response of ISGRI, strongly suppressed (30% of
optimal) response of IBIS/Veto, and near-optimal (74% of optimal)
response of SPI-ACS.

The background within +/-300 seconds around the event was rather
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 3.3e-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 ~2.9e-07 (7.2e-08)
erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range.

For the mean reported distance 2216.0 Mpc this corresponds to the
limit on the total isotropic equivalent energy in 1 s of 1.9e+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 (4.2e+49 erg/s)

We report for completeness and in order of FAP, all excesses
identified in the search region. We find: 8 likely background
excesses:

T-T0 | scale | S/N | luminosity ( x 1e+50 erg/s) | FAP
172 | 0.1 | 12 | 35.9 +/- 4.25 +/- 31 | 0.271
20.6 | 0.15 | 3.9 | 9.44 +/- 3.33 +/- 8.14 | 0.492
-23.3 | 0.15 | 3.9 | 9.47 +/- 3.33 +/- 8.16 | 0.58
-55.7 | 0.35 | 3.9 | 6.08 +/- 2.17 +/- 5.24 | 0.608
-18 | 0.4 | 3.2 | 4.76 +/- 2.02 +/- 4.1 | 0.617
236 | 3.55 | 3.3 | 17.1 +/- 6.75 +/- 14.8 | 0.666
120 | 1.1 | 3.5 | 3.16 +/- 1.22 +/- 2.73 | 0.719
175 | 0.95 | 3.8 | 3.62 +/- 1.31 +/- 3.12 | 0.725

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.

We note that despite a quite high S/N ratio the excess at T-T0=172 s is not considered as associated with the GW event.

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

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 S191215w event using the 90% contour of the Initial bayestar probability
map provided by the GW interferometers (GCN#26441
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  <https://gcn.gsfc.nasa.gov/gcn3/26441.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/S191215w_Initial.png <http://antares.in2p3.fr/GW/S191215w_Initial.png>.
Considering the location probability provided by the LIGO/Virgo collaborations, there is a
42.3% 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 2019-12-15 22:30:52 and in the 90% contour of the S191215w
event. The expected number of atmospheric background events in the region visible by ANTARES is
4.28e-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 3.08e-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.

M. Serino, S. Sugita (AGU),
N. Kawai (Tokyo Tech), H. Negoro (Nihon U.),
M. Nakajima, W. Maruyama, M. Aoki, K. Kobayashi, R. Takagi (Nihon U.),
T. Mihara, C. Guo, Y. Zhou, 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, 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 S191215w at 2019-12-15 22:30:52.333 UTC (GCN 26441
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 ).

At the trigger time of S191215w, the high-voltage of MAXI/GSC was on.
The instantaneous field of view of GSC at the GW trigger time covered 9% 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 42%
of the 90% credible region of the bayestar skymap from 22:30:52 to 22:55:17 UTC (T0+0 to T0+1465 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.

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

The HAWC Collaboration performed a follow-up of the gravitational wave
trigger S191215w (GCN #26441
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 ). At the time of the trigger the HAWC
local zenith was oriented towards (RA, Dec) = (324.5 deg, 18.9 deg).
50% 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 deg to 45 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 1.2e-6 erg/cm^2 to 1.1e-4 erg/cm^2
(6.4e-6 erg/cm^2 to 5.0e-4 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.

C. Fletcher (USRA) reports on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group

For S191215w and using the initial BAYESTAR skymap, Fermi-GBM was observing 49.2% 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 S191215w (GCN Circ. 26441
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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.

Part of the LVC localization region is behind the Earth for Fermi, located at RA=322.6, Dec=18.9 with a radius of 67.1 degrees. 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     Normal   Hard
------------------------------------
0.128 s:      2.6        3.5         9.1
1.024 s:      1.1        1.5         3.0
8.192 s:      0.15      0.29       0.76

Assuming the median luminosity distance of 2215.5 Mpc from the GW detection, we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^50 erg/s):
Timescale  Soft     Normal   Hard
------------------------------------
0.128s:       2.4       2.8          12.0
1.024s:       1.0       1.2          4.1
8.192s:       0.14      0.24       1.0

M. Pilia (INAF/OA-Cagliari), 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, C. Pittori (SSDC, and INAF/OAR),
A. Bulgarelli, V. Fioretti, N. Parmiggiani (INAF/OAS-Bologna), F. Longo
(Univ. Trieste, and INFN Trieste), report on behalf of the AGILE Team:

In response to the LIGO/Virgo GW event S191215w at T0 = 2019-12-15
22:30:52.333 (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 S191215w 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 S191215w localization region, from a minimum of 1.2E-06 erg
cm^-2 to a maximum of 1.6E-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), M. Pilia (INAF/OA-Cagliari),
M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), M. Cardillo,
C. Casentini, G. Piano, A. Ursi (INAF/IAPS), F. Lucarelli, C. Pittori
(SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, N. Parmiggiani
(INAF/OAS-Bologna), F. Longo (Univ. Trieste, and INFN Trieste), report
on behalf of the AGILE Team:

In response to the LIGO-Virgo GW event S191215w at T0 = 2019-12-15
22:30:52.333 UTC a preliminary analysis of the AGILE exposure at T0
shows that the Gamma-Ray Imaging Detector (GRID) exposure covered less
than 10% of the 90% c.l. localization region (LR) (35% of 90% c.l. LR
is occulted by Earth).

We performed an analysis of the GRID data in the energy range 50 MeV -
10 GeV over time intervals before and after T0, where good exposure of
the S191215w 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 2.0e-07 to 9.4e-07 erg cm^-2 s^-1, with exposure of about 45% of
the LR over the time interval ( T0 + 100s ; T0 + 200s );

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

V. Shenoy (IITB), Aarthy E. (PRL), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (TIFR), S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

We have carried a search for X-ray candidates in Astrosat CZTI data in a 100 sec window around the trigger time of the BBH merger event S191215w (UTC 2019-12-15 22:30:52.000, GraceDB event). CZTI is a coded aperture mask instrument that has considerable effective area for about 29% of the entire sky, but is also sensitive to brighter transients from the entire sky. At the time of merger, Astrosat's nominal pointing is RA,DEC = 2:08:55.5,-74:26:45.0 (32.2313,-74.4458), which is 107 deg away from the maximum probability location. At the time of merger event, the Earth-satellite-transient angle corresponding to maximum probability location is ~ 82.46 deg and hence is not occulted by Earth in satellite's frame. In a time interval of 100 sec around the event, the region of the localisation map which is not occulted by Earth in the satellite's frame has a cumulative probability of 0.83 (83%).

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 background count rates were estimated by using data from 10 (+-5) neighbouring orbits. We selected confidence levels such that the probability of a false trigger in a 1000 sec window is 10^-4. We do not find any evidence for any hard X-ray transient in this window, in the CZTI energy range of 20-200 keV.

We use a detailed mass model of the satellite to calculate the direction-dependent instrument response for points in the visible sky. We then assume the source is modelled as a power law with photon index alpha = -1, and convert our count rate upper limits to direction-dependent flux limits. We obtain the following upper limits for source flux in the 20-200 keV band by taking a probability weighted mean over the visible sky:

0.1 s: flux limit= 6.00e-06 ergs/cm^2/s; fluence limit = 6.00e-07 ergs/cm^2
1.0 s: flux limit= 1.98e-06 ergs/cm^2/s; fluence limit = 1.98e-06 ergs/cm^2
10.0 s: flux limit= 2.82e-07 ergs/cm^2/s; fluence limit = 2.82e-06 ergs/cm^2

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.

N. Omodei (Stanford Univ.), M. Arimoto (Kanazawa Univ.), M. Axelsson (KTH & Stockholm Univ.),  F. Longo (University and INFNN, Trieste), D. Kocevski (NASA/MSFC), and M. Crnogorcevic (Univ. of Maryland & NASA/GSFC)

report on behalf of the Fermi-LAT Collaboration:

We have searched data collected by the Fermi Large Area Telescope (LAT) on December 15th, 2019, for possible high-energy (E > 100 MeV) gamma-ray emission in spatial/temporal coincidence with the LIGO/Virgo trigger S191215w (GCN 26441
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 ). 

We define "instantaneous coverage" as the integral over the region of the LIGO/Virgo 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 ~56% of the LIGO probability at the time of the trigger (T0 = 2019-12-15 22:30:52 UTC), and reached 100% cumulative coverage after ~2.5 ks. 

We performed a search for a transient counterpart within the observed region of the 90% contour of LIGO/Virgo map in a fixed time window from T0 to T0 + 10 ks.

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, 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 3E-10 and 4E-9 [erg/cm^2/s].  

The Fermi-LAT point of contact for this event is  N. Omodei (nicola.omodei@stanford.edu).

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.

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (NASA/GSFC),
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-ASDC), 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 S191215w (LIGO/VIRGO Collaboration GCN Circ. 26441
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 ),
where T0 is the LVC trigger time (2019-12-15T22:30:52.333 UTC).

The center of the BAT field of view (FOV) at T0 is
RA = 79.194 deg,
DEC = -7.503 deg,
and the roll angle is 167.963 deg.
The BAT FOV (>10% partial coding) covers 18.28% of the integrated
LVC localization probability, and 17.80% 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 ~ 7.70 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 ~ 81.91 Mpc.

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

BAT retains decreased, but significant, sensitivity to rate increases for
gamma-ray events outside of its FOV. About 77.71% 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/S191215w/web/source_public.html

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 S191215w T0 = 2019-12-15 22:30:52.333 UT (The LIGO Scientific 
Collaboration and Virgo Collaboration, GCN Circ. 26441
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 ).

No CGBM on-board trigger occurred around the event time.  Based on the
LVC high probability localization region, the summed LIGO probabilities
inside the CGBM HXM (7 - 3000 keV) and SGM (40 keV - 28 MeV) fields
of view are 0 % and 45 %, respectively (and 51 % credible region of the
initial localization map was above the horizon).  The HXM and SGM fields
of view were centered at RA = 214.4 deg, Dec = 48.5 deg and 
RA = 222.3 deg, Dec = 40.2 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 S191215w. 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. There 
is no significant overlap with the LVC high probability localization 
region at T0+-60 sec. The CAL FOV was centered at RA=222.3 deg,
Dec=40.3 deg at T0.

P.A. Duverne (LAL), M. Blazek (HETH/IAA-CSIC), S. Agayeva (SHAO), M.
Masek (FZU), M. Boer (Artemis), N. Christensen (Artemis), L. Eymar
(Artemis), S. Karpov (FZU), A. Klotz (IRAP), K. Noysena (Artemis,
IRAP), S. Antier (APC), A. Coleiro (APC), D. Corre (LAL), M. Coughlin
(Caltech), D. Coward (OzGrav-UWA), J.G. Ducoin (LAL), B. Gendre
(OzGrav-UWA), P. Hello (LAL), D. A. Kann (HETH/IAA-CSIC), N.
Kochiashvili (Iliauni), C. Lachaud (APC), N. Leroy (LAL), C. Thoene
(HETH/IAA-CSIC), D. Turpin (AIM-CEA), X. Wang (THU)

report on behalf of the FRAM, TAROT and GRANDMA collaborations.

We performed tiled observations of LIGO/Virgo S191215w event with the
FRAM-Auger, TAROT-Chili (TCH), TAROT-Reunion (TRE) telescopes.

FRAM-Auger is located at Pierre Auger Observatory. TCH is located at
La Silla ESO observatory (LaS/ESO). TRE is located at Les Makes
astronomical observatory.

The following table shows for each telescope: the delay in minutes
from the trigger, which filter is used, the field of view of the
telescope in degrees and the typical limiting magnitude (AB mag) for a
  given exposure in seconds (s).

+-------------+---------+----------+-----------+------------+
| Telescope   | Delay   | Filter   | f.o.v.    | Limiting   |
|             | [min]   |          | [deg]     | Mag.       |
|-------------+---------+----------+-----------+------------|
| FRAM-Auger  | 300     | R        | 1.0 x 1.0 | 18.0 (60s) |
| TCH         | 134     | Clear    | 1.9 x 1.9 | 18.0 (60s) |
| TRE         | 37      | Clear    | 4.2 x 4.2 | 17.0 (60s) |
+-------------+---------+----------+-----------+------------+

We performed the following joint tiled observations [1] :

+-------------+------------+------------+---------+---------+---------+
| Telescope   | TStart     | TEnd       | RA      | DEC     | Proba   |
|             | [UTC]      | [UTC]      | [deg]   | [deg]   | [%]     |
|-------------+------------+------------+---------+---------+---------|
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 118.125 | -46.216 | 0.2     |
|             | 03:30:25   | 03:34:51   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 118.571 | -47.189 | 0.2     |
|             | 03:35:25   | 03:39:52   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 117.241 | -45.243 | 0.2     |
|             | 03:40:27   | 03:44:53   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 115.252 | -41.351 | 0.2     |
|             | 03:45:28   | 03:49:55   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 119.008 | -49.135 | 0.2     |
|             | 03:50:32   | 03:54:58   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 116.000 | -43.297 | 0.2     |
|             | 03:55:34   | 04:00:01   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 119.514 | -48.162 | 0.2     |
|             | 04:00:37   | 04:05:04   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 116.830 | -44.270 | 0.2     |
|             | 04:05:39   | 04:10:06   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 120.496 | -49.135 | 0.2     |
|             | 04:10:41   | 04:15:08   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 114.894 | -40.378 | 0.2     |
|             | 04:15:45   | 04:20:12   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 118.189 | -44.270 | 0.2     |
|             | 04:20:47   | 04:25:14   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 121.008 | -50.108 | 0.2     |
|             | 04:25:50   | 04:30:17   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 114.545 | -39.405 | 0.2     |
|             | 04:30:54   | 04:35:21   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 118.057 | -48.162 | 0.2     |
|             | 04:35:57   | 04:40:24   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 117.333 | -43.297 | 0.2     |
|             | 04:41:00   | 04:45:26   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 119.496 | -50.108 | 0.2     |
|             | 04:46:03   | 04:50:30   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 113.878 | -37.459 | 0.2     |
|             | 04:51:07   | 04:55:34   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 116.547 | -41.351 | 0.2     |
|             | 04:56:10   | 05:00:37   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 118.621 | -45.243 | 0.2     |
|             | 05:01:12   | 05:05:39   |         |         |         |
| FRAM-Auger  | 2019-12-16 | 2019-12-16 | 116.719 | -46.216 | 0.2     |
|             | 05:06:13   | 05:10:40   |         |         |         |
| -----       | -----      | -----      | -----   | -----   | -----   |
| TCH         | 2019-12-16 | 2019-12-17 | 110.619 | -39.959 | 0.2     |
|             | 00:44:40   | 01:40:58   |         |         |         |
| TCH         | 2019-12-16 | 2019-12-17 | 109.629 | -36.323 | 0.3     |
|             | 02:25:46   | 08:32:03   |         |         |         |
| TCH         | 2019-12-16 | 2019-12-17 | 115.312 | -49.050 | 0.3     |
|             | 02:51:58   | 06:28:19   |         |         |         |
| TCH         | 2019-12-16 | 2019-12-16 | 124.700 | -50.000 | 0.3     |
|             | 02:58:46   | 08:04:37   |         |         |         |
| TCH         | 2019-12-16 | 2019-12-17 | 155.824 | -70.868 | 0.3     |
|             | 05:15:13   | 08:51:32   |         |         |         |
| TCH         | 2019-12-16 | 2019-12-17 | 117.079 | -38.141 | 0.3     |
|             | 07:32:14   | 08:38:48   |         |         |         |
| TCH         | 2019-12-17 | 2019-12-17 | 324.176 | 21.859  | 0.7     |
|             | 00:49:12   | 00:55:31   |         |         |         |
| -----       | -----      | -----      | -----   | -----   | -----   |
| TRE         | 2019-12-15 | 2019-12-17 | 120.000 | -49.091 | 3.1     |
|             | 23:07:23   | 00:03:44   |         |         |         |
| TRE         | 2019-12-15 | 2019-12-15 | 111.892 | -32.727 | 2.4     |
|             | 23:39:31   | 23:45:54   |         |         |         |
| TRE         | 2019-12-15 | 2019-12-16 | 107.532 | -28.636 | 1.7     |
|             | 23:58:29   | 00:04:52   |         |         |         |
| TRE         | 2019-12-16 | 2019-12-16 | 112.208 | -28.636 | 1.3     |
|             | 20:39:33   | 20:45:49   |         |         |         |
| TRE         | 2019-12-16 | 2019-12-16 | 150.000 | -73.636 | 1.2     |
|             | 20:59:02   | 21:05:18   |         |         |         |
| TRE         | 2019-12-16 | 2019-12-16 | 105.366 | -20.455 | 1.0     |
|             | 21:17:47   | 21:24:09   |         |         |         |
| TRE         | 2019-12-16 | 2019-12-16 | 120.000 | -40.909 | 1.0     |
|             | 21:31:00   | 21:37:22   |         |         |         |
| TRE         | 2019-12-17 | 2019-12-17 | 113.143 | -36.818 | 2.9     |
|             | 00:23:00   | 00:29:18   |         |         |         |
+-------------+------------+------------+---------+---------+---------+

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.

These observations cover about 19.2% of the cumulative probability of
the BAYESTAR skymap created on 2019-12-15 22:31:49 (UTC).

The coverage map is available at:
https://grandma-
owncloud.lal.in2p3.fr/index.php/s/XgtMhPRxcyL09gR/download?path=%2F&files=GRANDMA_S191215w_1576581828.png

No significant transient candidates were found during our low latency
analysis [2,3].

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 [2](https://grandma.lal.in2p3.fr/).

Details on the different telescopes are available on the GRANDMA web
pages.

[1] M. W Coughlin et al., MNRAS 2019, https://doi.org/10.1093/mnras/stz2485
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[2] S. Antier et al., MNRAS 2019, https://doi.org/10.1093/mnras/stz3142
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[3] K. Noysena et al., ApJ 2019, arXiv:1910.02770
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The LIGO Scientific Collaboration and the Virgo Collaboration report:

We have conducted further analysis of the LIGO Hanford Observatory
(H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1)
data around the time of the compact binary merger (CBC) candidate
S191215w (GCN Circular 26441
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 ).
Parameter estimation has been performed using LALInference [1] and a
new sky map, LALInference.fits.gz,0, distributed via GCN Notice, is
available for retrieval from the GraceDB event page:

https://gracedb.ligo.org/superevents/S191215w

The preferred sky map at this time is LALInference.fits.gz,0. For the
LALInference.fits.gz,0 sky map, the 90% credible region is 361 deg2.
Marginalized over the whole sky, the a posteriori luminosity distance
estimate is 1770 +/- 455 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)

A. Ridnaia, S. Golenetskii, R.Aptekar, D. Frederiks,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, 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 S191215w (2019-12-15 22:30:52.333 UTC, hereafter T0;
LIGO/Virgo Collaboration GCN Circ. 26441
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 ).

No triggered KW GRBs happened ~13 days before and ~2 days
after T0. The closest waiting-mode GRB was observed ~23 hours before 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 20 - 1500 keV fluence
to 8.5x10^-7 erg/cm^2 for a burst lasting less than 2.944 s and having a
typical KW short GRB spectrum (an exponentially cut off power law with
alpha =-0.5 and Ep=500 keV). For a typical long GRB spectrum (the Band
function with alpha=-1, beta=-2.5, and Ep=300 keV), the corresponding
limiting peak flux is 2.6x10^-7 erg/cm^2/s (20 - 1500 keV, 2.944 s scale).

All the quoted values are preliminary.