LIGO/Virgo S190924h
GCN Circular 25909
Subject
LIGO/Virgo S190924h: Correction to GCN 25905, updated sky localization for S190924h
Date
2019-10-01T19:32:24Z (6 years ago)
From
Geoffrey Mo at LIGO <geoffrey.mo@ligo.org>
What follows is the exact content of GCN 25905, 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). 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)
GCN Circular 25845
Subject
LIGO/Virgo S190924h: No counterpart candidates in Fermi-LAT observations
Date
2019-09-25T04:54:53Z (6 years ago)
From
Magnus Axelsson at Stockholm U. <magaxe@kth.se>
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).
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.
GCN Circular 25844
Subject
LIGO/Virgo S190924h: Not observable by CALET
Date
2019-09-25T04:15:11Z (6 years ago)
From
Yuta Kawakubo at Louisiana State U./CALET <kawakubo1@lsu.edu>
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), 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.
GCN Circular 25843
Subject
LIGO/Virgo S190924h: no counterpart candidates in the Swift/BAT observations
Date
2019-09-25T01:21:33Z (6 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
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),
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
GCN Circular 25841
Subject
LIGO/Virgo S190924h: Upper limits from Fermi-GBM Observations
Date
2019-09-24T12:05:42Z (6 years ago)
From
Eric Burns at GSFC <erickayserburns@gmail.com>
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