LIGO/Virgo S190924h

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
S190924h
 in a time range of 1000 seconds [3] centered on the alert event time
(2019-09-24 02:10:26.847 UTC to 2019-09-24 02:27:06.847 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 S190924h 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 S190924h ranges from  0.029 to 0.303 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
Loading...
 
  (2018) and Countryman et
al.arXiv:1901.05486
Loading...
 
  (2019)
[2] Braun et al., Astroparticle Physics 29, 299 (2008)
[3] Baret et al., Astroparticle Physics 35, 1 (2011)

The LIGO Scientific Collaboration and the Virgo Collaboration report:

We identified the compact binary merger candidate S190924h during
real-time processing of data from LIGO Hanford Observatory (H1), LIGO
Livingston Observatory (L1), and Virgo Observatory (V1) at 2019-09-24
02:18:46.847 UTC (GPS time: 1253326744.847). The candidate was found
by the GstLAL [1], PyCBC Live [2], MBTAOnline [3], and SPIIR [4]
analysis pipelines.

S190924h is an event of interest because its false alarm rate, as
estimated by the online analysis, is 8.9e-19 Hz, or about one in 1e11
years. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S190924h

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

Assuming the candidate is astrophysical in origin, there is
indeterminate evidence for the lighter compact object having a mass <
3 solar masses (HasNS: 30%). 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,0, an updated localization generated by BAYESTAR
[5], distributed via GCN notice about 6 minutes after the candidate

For the bayestar.fits.gz,0 sky map, the 90% credible region is 515
deg2. Marginalized over the whole sky, the a posteriori luminosity
distance estimate is 514 +/- 132 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] Nitz et al. PRD 98, 024050 (2018)
 [3] Adams et al. CQG 33, 175012 (2016)
 [4] Qi Chu, PhD Thesis, The University of Western Australia (2017)
 [5] Singer & Price PRD 93, 024013 (2016)

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 S190924h errorbox  1759 sec after notice time and 2222 sec after trigger time at 2019-09-24 02:55:48 UT, with upper limit up to  18.9 mag. The observations began at zenit distance = 73 deg. The sun  altitude  is -19.9 deg. 

MASTER-IAC robotic telescope  located in Spain (IAC Teide Observatory) started inspect of the LIGO/Virgo S190924h errorbox  2641 sec after notice time and 3104 sec after trigger time at 2019-09-24 03:10:30 UT, with upper limit up to  15.2 mag. The observations began at zenit distance = 85 deg. The sun  altitude  is -47.3 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=10835

We obtain a following upper limits.  

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

    2312 | 2019-09-24 02:55:48 |         MASTER-SAAO | (09h 19m 04.417s , -05d 52m 26.63s) |   C |   180 | 17.3 |        
    2531 | 2019-09-24 02:59:27 |         MASTER-SAAO | (09h 05m 19.012s , -07d 52m 15.64s) |   C |   180 | 18.9 |        
    2914 | 2019-09-24 03:05:49 |         MASTER-SAAO | (08h 33m 39.336s , +15d 54m 26.45s) |   C |   180 | 16.7 |        
    3194 | 2019-09-24 03:10:30 |          MASTER-IAC | (08h 27m 34.435s , +15d 53m 04.11s) |  P| |   180 | 15.2 |        
Filter C is a clear (unfiltred) band. 


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

N. Kawai (Tokyo Tech), H. Negoro (Nihon U.),
S. Sugita, M. Serino (AGU),
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 S190924h at 2019-09-24 02:18:46.846 UTC (GCN 25829
Loading...
 
 ).

At the trigger time of S190924h, the high-voltage of MAXI/GSC was off,
and it was turned on at T0+1113 sec (+18.6 min).
The first one-orbit (92 min) scan observation with GSC after the event
covered 34%
of the 90% credible region of the bayestar skymap from 02:50:13 to
02:59:43 UTC (T0+1887 to T0+2457 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.

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 S190924h event using the 90% contour of the Initial bayestar probability
map provided by the GW interferometers (GCN#25829
Loading...
 
  <https://gcn.gsfc.nasa.gov/gcn3/25829.gcn3
Loading...
 
 >). 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/S190924h_Initial.png <http://antares.in2p3.fr/GW/S190924h_Initial.png>.
Considering the location probability provided by the LIGO/Virgo collaborations, there is a
39.6% 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 2019-09-24 02:18:46 and in the 90% contour of the S190924h
event. The expected number of atmospheric background events in the region visible by ANTARES is
1.90e-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 1.37e-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.

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

Using combination of INTEGRAL all-sky detectors (following [1]):
SPI/ACS, IBIS/Veto, and IBIS we have performed a search for a prompt
gamma-ray counterpart of S190924h (GCN 25829
Loading...
 
 ).

At the time of the event (2019-09-24 02:18:46 UTC, hereafter T0),
INTEGRAL was operating in nominal mode. The peak of the event
localization probability was at an angle of 124 deg with respect to
the spacecraft pointing axis. This orientation implies strongly
suppressed (4.3% of optimal) response of ISGRI, somewhat suppressed
(57% of optimal) response of IBIS/Veto, and strongly suppressed (31%
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]), 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 4.2e-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 ~3.8e-07 (7.5e-08)
erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range.

For the mean reported distance 514.0 Mpc this corresponds to the limit
on the total isotropic equivalent energy in 1 s of 1.3e+49 erg for
the short GRB spectrum and for a long GRB spectrum isotropic
equivalent luminosity in 1 s (8 s) of 6.5e+48 erg/s (2.4e+48 erg/s)

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

scale | T | S/N | luminosity ( x 1e+49 erg/s) | FAP 
0.05 | -0.312 | 3 | 5.68 +/- 2.41 +/- 3.89 | 0.115 
0.35 | -13.1 | 3.9 | 27.8 +/- 8.99 +/- 19 | 0.133 
0.1 | -2.39 | 3.4 | 4.49 +/- 1.69 +/- 3.08 | 0.209 
1 | -42.4 | 3.6 | 15.1 +/- 5.29 +/- 10.3 | 0.253 
0.7 | 90.3 | 4 | 19.9 +/- 6.33 +/- 13.7 | 0.402 
0.15 | -4.71 | 3.1 | 3.35 +/- 1.38 +/- 2.29 | 0.514 
1 | 292 | 4.4 | 18.2 +/- 5.3 +/- 12.5 | 0.64 
0.55 | -95.5 | 3.6 | 20.1 +/- 7.15 +/- 13.7 | 0.939 

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

M. Cardillo, G. Piano (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma
Tor Vergata), C. Casentini, A. Ursi (INAF/IAPS), F. Lucarelli, C.
Pittori, F. Verrecchia (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 S190924h at T0 = 2019-09-24
02:18:46 (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 10% of the S190924h 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 S190924h localization region, from a minimum of
1.60E-06 erg cm^-2 to a maximum of 7.42E-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.

G. Piano, M. Cardillo (INAF/IAPS), F. Verrecchia (SSDC, and INAF/OAR), M.
Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), C. Casentini, 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 S190924h at T0 =  2019-09-24
02:18:46.847 UTC, a preliminary analysis of the AGILE data at T0 shows that
the Gamma-Ray Imaging Detector (GRID) has no exposure of the 90% c.l.
localization region (LR).

The closest exposure in time occurred at T0 - 400 s, covering about 40% of
the LR. We performed an analysis of the GRID data in the energy range 50
MeV - 10 GeV. The following preliminary GRID 3-sigma upper limit (UL) value
is obtained over the exposed region of the LR:

from 7.7e-08 to 3.0e-07 erg cm^-2 s^-1, over the time interval (T0 - 400 s;
T0 - 300 s).

This measurement was obtained with AGILE observing a large portion of the
sky in spinning mode. Additional analysis of AGILE data is in progress.

E. Burns (NASA/GSFC) reports on behalf of the Fermi-GBM Team and the
GBM-LIGO/Virgo group

For S190924h and using the initial bayestar skymap, Fermi-GBM was observing
100% 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 S190924h (GCN 25829
Loading...
 
 ). 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 set upper limits on impulsive gamma-ray emission for the LVC
localization region. Using the representative soft, normal, and hard
GRB-like templates described in arXiv:1612.02395
Loading...
 
 , 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:     5.9     8.9     15.
1.024 s:     1.6     3.0     5.4
8.192 s:     0.3     0.6     1.1

Assuming the median luminosity distance of 514 Mpc from the GW detection,
we estimate the following intrinsic luminosity upper limits over the 1
keV-10 MeV energy range (in units of 10^49 erg/s):

Timescale  Soft     Normal   Hard
------------------------------------
0.128 s:     2.7          3.8         11.
1.024 s:     0.7          1.3         3.8
8.192 s:     0.1          0.3         1.1

D. M. Palmer (LANL), S. D. Barthelmy (NASA/GSFC),
A. Y. Lien (GSFC/UMBC), 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),
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 S190924h (LIGO/VIRGO Collaboration GCN Circ. 25829
Loading...
 
 ),
where T0 is the LVC trigger time (2019-09-24T02:18:46.846 UTC).

The center of the BAT field of view (FOV) at T0 is
RA = 159.491 deg,
DEC = 44.352 deg,
and the roll angle is 157.702 deg.
The BAT FOV (>10% partial coding) covers 70.30% of the integrated
LVC localization probability, and 71.67% of the galaxy convolved
probability (Evans et al. 2016). Note that Swift was slewing
from ~T0-10 s to ~T0+160 s. Also, 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 ~ 2.57 x 10^-7 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 ~ 44.79 Mpc.

No event data are available at this time.

BAT retains decreased, but significant, sensitivity to rate increases for
gamma-ray events outside of its FOV. About 29.70% 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/S190924h/web/source_public.html

T. Sakamoto, A. Yoshida, 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:

At the trigger time of the compact binary merger candidate S190924h,
T0 = 2019-09-24 02:18:46.847 UT (The LIGO Scientific Collaboration 
and Virgo Collaboration, GCN Circ. 25829
Loading...
 
 ), the CALET Gamma-ray 
Burst Monitor (CGBM) high voltages were off (from T0-1 min to 
T0+16 min).

The CALET Calorimeter (CAL) was operating in the high energy
trigger mode at the trigger time of S190924h. 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 high probability 
localization region.  The CAL FOV was centered at RA=273.4 deg,
Dec=40.2 deg at T0.

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

We have searched data collected by the Fermi Large Area Telescope (LAT) on Sep 24, 2019, for possible high-energy (E > 100 MeV) gamma-ray emission in spatial/temporal coincidence with the LIGO/Virgo trigger S190924h (GCN 25829
Loading...
 
 ).

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 ~65% of the LIGO probability region at the time of the trigger (T0 = 2019-09-24 02:18:46.847 UTC) and reached 100% cumulative coverage at approximately T0 + 5.2 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 between 100 MeV and 1 GeV for the fixed time interval of this search vary between 2.3e-10 and 3.2e-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.

What follows is the exact content of GCN 25905
Loading...
 
 , which is being re-sent with
a corrected subject. The original subject stated that this was an updated sky
localization for S190828j, which was in error. Instead, this is the updated sky
localization for S190924h.

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 S190924h
(GCN Circular 25829
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/S190924h

The preferred sky map at this time is LALInference.fits.gz. The 90%
credible region is 303 deg2. Marginalized over the whole sky, the a
posteriori luminosity distance estimate is 548 +/- 112 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)