TITLE: GCN CIRCULAR
NUMBER: 35211
SUBJECT: LIGO/Virgo/KAGRA S231129ac: Identification of a GW compact binary merger candidate
DATE: 23/11/29 09:48:01 GMT
FROM: Pablo García Abia at CIEMAT <pablo.garcia(a)ciemat.es>
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We identified the compact binary merger candidate S231129ac during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2023-11-29 08:17:45.643 UTC (GPS time: 1385281083.643). The candidate was found by the CWB [1], GstLAL [2], and SPIIR [3] analysis pipelines.
S231129ac is an event of interest because its false alarm rate, as estimated by the online analysis, is 1.8e-08 Hz, or about one in 1 year, 9 months. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S231129ac
The classification of the GW signal, in order of descending probability, is BBH (99%), Terrestrial (1%), NSBH (<1%), or BNS (<1%).
There was a high rate of noise transients (glitches) in the LIGO Hanford detector which may affect the parameters or the significance of the candidate.
Assuming the candidate is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [4] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [4] Both HasNS and HasRemnant consider the support of several neutron star equations of state. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassgap) is <1%.
Two sky maps are available at this time and can be retrieved from the GraceDB event page:
* bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [5], distributed via GCN notice about a minute after the candidate event time.
* bayestar.multiorder.fits,2, an initial localization generated by BAYESTAR [5], distributed via GCN notice about 5 minutes after the candidate event time.
The preferred sky map at this time is bayestar.multiorder.fits,2. For the bayestar.multiorder.fits,2 sky map, the 90% credible region is 3175 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 5958 +/- 1935 Mpc (a posteriori mean +/- standard deviation).
For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/userguide/.
[1] Klimenko et al. PRD 93, 042004 (2016)
[2] Tsukada et al. PRD 108, 043004 (2023) and Ewing et al. arXiv:2305.05625 (2023)
[3] Chu et al. PRD 105, 024023 (2022)
[4] Chatterjee et al. ApJ 896, 54 (2020)
[5] Singer & Price PRD 93, 024013 (2016)
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TITLE: GCN CIRCULAR
NUMBER: 35210
SUBJECT: GRB 231129A: GECAM-C detection of a long burst
DATE: 23/11/29 09:29:57 GMT
FROM: wenlongzhang2018(a)163.com
Wen-Long Zhang, Shao-Lin Xiong report on behalf of the GECAM team:
GECAM-C was triggered in-flight by a long burst, GRB 231129A, at 2023-11-29T05:06:01.850 UTC (T0), which was also observed by Swift/BAT (GCN #35208) and INTEGRAL (GCN #35209).
According to the realtime alert data, the GECAM-C light curve shows roughly two peaks with a total duration of ~80 sec (15-1050 keV).
The time-averaged spectrum of GECAM-C realtime data from about T0 to T0+4 s could be
adequately fit by a cut-off power-law with a fluence about 1.84E-6 erg/cm^2 in 20-1000 keV.
GECAM location is consistent with that of Swift/BAT and INTEGRAL within the error.
We note that these results are based on realtime alert data and thus very preliminary. Refined analysis will be reported later.
Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).
View this GCN Circular online at https://gcn.nasa.gov/circulars/35210.
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TITLE: GCN CIRCULAR
NUMBER: 35209
SUBJECT: GRB 231129A: INTEGRAL detection of a long GRB
DATE: 23/11/29 08:37:29 GMT
FROM: Sandro Mereghetti at IASF-Milano/INAF <sandro.mereghetti(a)inaf.it>
S.Mereghetti (INAF, IASF-Milano), D.Gotz (CEA, Saclay), C.Ferrigno, E.Bozzo, V.Savchenko (ISDC, Versoix), L.Ducci (IAAT, Germany and ISDC, Versoix) and J.Borkowski (CAMK, Torun) report:
a gamma ray burst lasting about 150 s has been detected by IBAS in the IBIS/ISGRI data at 05:05:59 UT of November 25, 2023. The burst has also been detected by Swift (Gropp et al. GCN 35208)
The refined coordinates (J2000) are:
R.A.= 317.53411 deg
DEC.= +41.51942 deg
with an uncertainty of 1.5 arcmin (90% c.l.).
The burst had a peak flux of about 0.5 ph/cm2/s (20-200 keV, 1-s integration time) and a fluence in the same energy range of about 6e-7 erg/cmq.
A plot of the light curve will be posted at
http://ibas.iasf-milano.inaf.it/IBAS_Results.html
View this GCN Circular online at https://gcn.nasa.gov/circulars/35209.
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TITLE: GCN CIRCULAR
NUMBER: 35208
SUBJECT: GRB 231129A: Swift detection of a burst
DATE: 23/11/29 05:19:12 GMT
FROM: Aaron Tohuvavohu at University of Toronto <aaron.tohu(a)gmail.com>
J.D. Gropp (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII),
D. M. Palmer (LANL), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto)
report on behalf of the Neil Gehrels Swift Observatory Team:
At 05:05:59 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 231129A (trigger=1199764). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 317.536, +41.544 which is
RA(J2000) = 21h 10m 09s
Dec(J2000) = +41d 32' 37"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a complex
structure with a duration of about 120 sec. The peak count rate
was ~3700 counts/sec (15-350 keV), at ~90 sec after the trigger.
The XRT began observing the field at 05:07:51.1 UT, 112.0 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 317.54581, 41.52062 which
is equivalent to:
RA(J2000) = 21h 10m 10.99s
Dec(J2000) = +41d 31' 14.2"
with an uncertainty of 4.0 arcseconds (radius, 90% containment). This
location is 88 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at https://www.swift.ac.uk/sper. We
cannot determine whether the source is fading at the present time. No
spectrum from the promptly downlinked event data is yet available to
determine the column density.
The initial flux in the 0.1 s image was 3.05e-08 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 120 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
Results from the list of sources generated on-board are not available at this
time. No correction has been made for the large, but uncertain, extinction
expected.
Burst Advocate for this burst is J.D. Gropp (jdg44 AT psu.edu).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)
View this GCN Circular online at https://gcn.nasa.gov/circulars/35208.
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TITLE: GCN CIRCULAR
NUMBER: 35207
SUBJECT: LIGO/Virgo/KAGRA S231127cg: Updated Sky localization
DATE: 23/11/28 21:44:47 GMT
FROM: mpuerrer(a)uri.edu
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We have conducted further analysis of the LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) data around the time of the compact binary merger (CBC) candidate S231127cg (GCN Circular 35202). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page:
https://gracedb.ligo.org/superevents/S231127cg
For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 3450 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 4425 +/- 1718 Mpc (a posteriori mean +/- standard deviation).
For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/userguide/.
[1] Ashton et al. ApJS 241, 27 (2019) and Morisaki et al. arXiv:2307.13380 (2023)
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TITLE: GCN CIRCULAR
NUMBER: 35205
SUBJECT: GRB 231123C: Fermi GBM Observation
DATE: 23/11/28 00:38:45 GMT
FROM: Sarah Dalessi at UAH <sd0104(a)uah.edu>
S. Dalessi (UAH), S. Lesage (UAH) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 19:58:25.38 UT on 23 November 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 231123C (trigger 722462310/231123832).
which was also detected by Swift/BAT-GUANO (J. DeLaunay et al. 2023, GCN 35179).
The Fermi Final Localization was reported in GCN 35171.
The angle from the Fermi LAT boresight is 90 degrees.
The GBM light curve single peak with a duration (T90)
of about 0.4 s (50-300 keV). The time-averaged spectrum
from T0-0.1 to T0+0.4 s is best fit by
a Power law function with alpha = -1.29 +/- 0.06.
The event fluence (10-1000 keV) in this time interval is
(3.3 +/- 0.4)E-07 erg/cm^2. The 64-ms peak photon flux measured
starting from T0-0.064 s in the 10-1000 keV band is 5 +/- 1 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
View this GCN Circular online at https://gcn.nasa.gov/circulars/35205.
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TITLE: GCN CIRCULAR
NUMBER: 35204
SUBJECT: GRB 231123B: Fermi GBM Observation
DATE: 23/11/27 23:30:13 GMT
FROM: Sarah Dalessi at UAH <sd0104(a)uah.edu>
S. Dalessi (UAH), S. Lesage (UAH) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 19:25:21.51 UT on 23 November 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 231123B (trigger 722460326/231123809).
which was also detected by Swift/BAT-GUANO (J. DeLaunay et al. 2023, GCN 35195).
The Fermi Final Localization was reported in GCN 35170.
The angle from the Fermi LAT boresight is 104 degrees.
The GBM light curve single peak with a duration (T90)
of about 77 s (50-300 keV). The time-averaged spectrum
from T0+0.003 to T0+76.802 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.2 +/- 0.2 and the cutoff energy,
parameterized as Epeak, is 160 +/- 38 keV.
The event fluence (10-1000 keV) in this time interval is
(5.9 +/- 0.7)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.5 s in the 10-1000 keV band is 1.9 +/- 0.3 ph/s/cm^2.
The spectrum is also well fit a Band function with Epeak = 115 +/- 44 keV,
alpha = -1.05 +/- 0.28, and beta = -2.16 +/- 0.31.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
View this GCN Circular online at https://gcn.nasa.gov/circulars/35204.
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TITLE: GCN CIRCULAR
NUMBER: 35203
SUBJECT: IceCube-231125A: Upper limits from a search for additional neutrino events in IceCube
DATE: 23/11/27 20:34:35 GMT
FROM: Jessie Thwaites at IceCube/U Wisc-Madison <thwaites(a)wisc.edu>
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-231125A (https://gcn.nasa.gov/circulars/35194) in a time range of 1000 seconds centered on the alert event time (2023-11-25 22:26:36.640 UTC to 2023-11-25 22:43:16.640 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-231125A. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-231125A ranges from 1.5e-01 to 1.7e-01 GeV cm^-2 in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 2e+02 GeV and 5e+04 GeV.
A subsequent search was performed including 2 days of data centered on the alert event time (2023-11-24 22:34:56.640 UTC to 2023-11-26 22:34:56.640 UTC). In this case, we report a p-value of 0.81, consistent with no significant excess of track events. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-231125A ranges from 1.8e-01 to 2.1e-01 GeV cm^-2 in a 2 day 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(a)icecube.wisc.edu.
[1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021)
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TITLE: GCN CIRCULAR
NUMBER: 35202
SUBJECT: LIGO/Virgo/KAGRA S231127cg: Identification of a GW compact binary merger candidate
DATE: 23/11/27 17:28:50 GMT
FROM: Evan Goetz at The University of British Columbia <evan.goetz(a)ligo.org>
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We identified the compact binary merger candidate S231127cg during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2023-11-27 16:53:00.882 UTC (GPS time: 1385139198.882). The candidate was found by the CWB [1], GstLAL [2], MBTA [3], PyCBC Live [4], and SPIIR [5] analysis pipelines.
S231127cg is an event of interest because its false alarm rate, as estimated by the online analysis, is 5.8e-09 Hz, or about one in 5 years. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S231127cg
The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%).
Noise transients (glitches) present in the LIGO Livingston detector and LIGO Hanford detector data identified at the time of this candidate may affect the parameters or the significance of the candidate.
Assuming the candidate is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [6] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [6] Both HasNS and HasRemnant consider the support of several neutron star equations of state. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassgap) is <1%.
Two sky maps are available at this time and can be retrieved from the GraceDB event page:
* bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [7], distributed via GCN notice about 26 seconds after the candidate event time.
* bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [7], distributed via GCN notice about 5 minutes after the candidate event time.
The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 3284 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 4796 +/- 1589 Mpc (a posteriori mean +/- standard deviation).
For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/userguide/.
[1] Klimenko et al. PRD 93, 042004 (2016)
[2] Tsukada et al. PRD 108, 043004 (2023) and Ewing et al. arXiv:2305.05625 (2023)
[3] Aubin et al. CQG 38, 095004 (2021)
[4] Dal Canton et al. ApJ 923, 254 (2021)
[5] Chu et al. PRD 105, 024023 (2022)
[6] Chatterjee et al. ApJ 896, 54 (2020)
[7] Singer & Price PRD 93, 024013 (2016)
View this GCN Circular online at https://gcn.nasa.gov/circulars/35202.
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