TITLE: GCN CIRCULAR
NUMBER: 36476
SUBJECT: LIGO/Virgo/KAGRA S240514x: Identification of a GW compact binary merger candidate
DATE: 24/05/14 12:59:12 GMT
FROM: Michele Valentini at VU Amsterdam - Nikhef <mvalenti(a)nikhef.nl>
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We identified the compact binary merger candidate S240514x during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2024-05-14 12:17:13.721 UTC (GPS time: 1399724251.721). The candidate was found by the CWB [1], GstLAL [2], MBTA [3], and PyCBC Live [4] analysis pipelines.
S240514x is an event of interest because its false alarm rate, as estimated by the online analysis, is 3.2e-10 Hz, or about one in 1e2 years. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S240514x
After parameter estimation by RapidPE-RIFT [5], the classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%).
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,1, an initial localization generated by BAYESTAR [7], distributed via GCN notice about 36 seconds after the candidate event time.
* bayestar.multiorder.fits,2, 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,2. For the bayestar.multiorder.fits,2 sky map, the 90% credible region is 271 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2453 +/- 566 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/.
[1] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004
[2] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. (2023) arXiv:2305.05625
[3] Aubin et al. CQG 38, 095004 (2021) doi:10.1088/1361-6382/abe913
[4] Dal Canton et al. ApJ 923, 254 (2021) doi:10.1088/1361-6382/abe913
[5] Rose et al. (2022) arXiv:2201.05263 and Pankow et al. PRD 92, 023002 (2015) doi:10.1103/PhysRevD.92.023002
[6] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe
[7] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013
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TITLE: GCN CIRCULAR
NUMBER: 36475
SUBJECT: GRB 240514D: AstroSat CZTI detection
DATE: 24/05/14 11:00:09 GMT
FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in>
J. Joshi (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long-duration GRB 240514D. Inspection of INTEGRAL/SPI-ACS data also showed the detection of the burst.
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2024-05-14 00:43:13.50 UTC. The measured peak count rate associated with the burst is 146 (+35, -35) counts/s above the background in the combined data of all quadrants, with a total of 507 (+127, -137) counts. The local mean background count rate was 312 (+3, -4) counts/s. Using cumulative rates, we measure a T90 of 5.8 (+1.5, -2.1) s.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2024-05-14 00:43:11.64 UTC. The measured peak count rate associated with the burst is 980 (+79, -82) counts/s above the background in the combined data of all quadrants, with a total of 3424 (+256, -276) counts. The local mean background count rate was 1302 (+6, -7) counts/s. We measure a T90 of 5.6 (+1.0, -0.4) s from the cumulative Veto light curve.
CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.
CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb
View this GCN Circular online at https://gcn.nasa.gov/circulars/36475.
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TITLE: GCN CIRCULAR
NUMBER: 36473
SUBJECT: LIGO/Virgo/KAGRA S240514c: Identification of a GW compact binary merger candidate
DATE: 24/05/14 09:25:02 GMT
FROM: mvalenti(a)nikhef.nl
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We identified the compact binary merger candidate S240514c during real-time processing of data from LIGO Livingston Observatory (L1) at 2024-05-14 08:03:21.048 UTC (GPS time: 1399709019.048). The candidate was found by the GstLAL [1] analysis pipeline.
S240514c is an event of interest because its false alarm rate, as estimated by the online analysis, is 9.6e-09 Hz, or about one in 3 years. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S240514c
After parameter estimation by RapidPE-RIFT [2], the classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%).
Low-frequency excess of noise was present in LIGO Livingston detector at the time of the event, 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%. [3] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [3] 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%.
Three 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 [4], distributed via GCN notice about 28 seconds after the candidate event time.
* bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [4], distributed via GCN notice about 47 seconds after the candidate event time.
* bayestar.multiorder.fits,2, an initial localization generated by BAYESTAR [4], 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 24219 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 3762 +/- 1324 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/.
[1] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. (2023) arXiv:2305.05625
[2] Rose et al. (2022) arXiv:2201.05263 and Pankow et al. PRD 92, 023002 (2015) doi:10.1103/PhysRevD.92.023002
[3] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe
[4] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013
View this GCN Circular online at https://gcn.nasa.gov/circulars/36473.
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TITLE: GCN CIRCULAR
NUMBER: 36471
SUBJECT: transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
DATE: 24/05/14 04:37:22 GMT
FROM: wangbc(a)bao.ac.cn
Y. M. Mao (NAOC), R. Wang (NAOC), B. C. Wang (NAOC), J. J. Jin (NAOC), L. Ge (NAOC), Z. Fan (NAOC), H. Wu (NAOC), J. Zheng (NAOC) report on behalf of Xinglong Nearby Galaxy Supernova Survey:
We observed the field of the optical transient AT2024iss that was detected by GOTO, using a 10.6cm refraction telescope located at xinglong observatory, naoc. We obtained 9 x 120 s frames in both RGB bands, with a median time of 2024-05-12T14:35:20Z frames, i.e., 7 hr before the GOTO detection. The 7σ limiting magnitude of the stacked RGB images are 17.8, 18, and 18.2 mag,
respectively. Photometry of the candidate and the field stars are obtained using SEP, and the RGB bands are calibrated using the r, V, and g band of the APASS catalog, respectively. The measured magnitudes are listed in the table below.
We performed forced photometry on the data from 24h ago, and the results of the photometry in all bands were below the detection limit and no signal was detected.
+-----------+---------------+--------+--------------------+
| ID | JD | filter | magnitude | +-----------+---------------+--------+--------------------+
| AT2024iss | 2460442.141 | g | >18.2 |
| AT2024iss | 2460442.140 | V | >18.0 |
| AT2024iss | 2460442.139 | r | >17.8 |
| AT2024iss | 2460443.147 | g | 14.37 +/- 0.01 |
| AT2024iss | 2460443.146 | V | 14.67 +/- 0.01 |
| AT2024iss | 2460443.145 | r | 14.65 +/- 0.02 |
+-----------+---------------+--------+--------------------+
Further observations are encouraged.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36471.
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TITLE: GCN CIRCULAR
NUMBER: 36470
SUBJECT: Fermi Gamma-ray Burst Monitor triggers 737345659/240514093 and GRB240514A are not GRBs
DATE: 24/05/14 04:21:40 GMT
FROM: Oliver J Roberts at USRA/NASA <oliver.roberts(a)nasa.gov>
"The Fermi Gamma-ray Burst Monitor (GBM) triggers 737345659/240514093 at 02:14:14.06 UT
and 737344032/240514074 (GRB240514A) at 01:47:07.40 UT on 14 May 2024, tentatively
classified as GRBs, are in fact not due to GRBs. These triggers are likely due to an X-class Solar Flare."
View this GCN Circular online at https://gcn.nasa.gov/circulars/36470.
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TITLE: GCN CIRCULAR
NUMBER: 36468
SUBJECT: LIGO/Virgo/KAGRA S240507p: Upper limits from Swift/BAT-GUANO
DATE: 24/05/14 03:32:34 GMT
FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu>
Samuele Ronchini (PSU), Aaron Tohuvavohu (U Toronto), Gayathri Raman (PSU), Tyler Parsotan (NASA GSFC), James DeLaunay (PSU), Jamie A. Kennea (PSU) report:
Swift/BAT was observing 100% of the GW localization probability (bayestar.multiorder.fits) at merger time. A fraction 19% of the GW localization posterior is contained inside the BAT coded FoV.
The LVK notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).
Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.
Using the NITRATES analysis (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), we searched for emission on 8 timescales from 0.128s to 16.384s in the interval [-20,+20] seconds around the merger time. We find no evidence for a signal, and derive the following upper limits.
We quote the 5-sigma flux upper limits in the 15-350 keV band, weighted over the GW localization, for four spectral templates (soft, normal, and hard GRB-like templates described in [arXiv:1612.02395], and spectral shape from GRB170817A [arXiv:1710.05446]) and for four time bins.
In units of 10^-7 erg/s/cm^2:
time_bin (s) soft normal hard GRB170817
------------------------------------
0.256 14.1 9.15 8.13 10.2
1.024 7.16 4.65 4.13 5.19
4.096 3.82 2.48 2.20 2.77
16.384 2.32 1.51 1.34 1.69
The upper limits as function of sky position are plotted here, alongside the GW localization:
https://doi.org/10.5281/zenodo.11188179
The solid and dashed lines indicate the 90% and 50% GW contour levels, respectively. The corresponding fits file is also included.
GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.
A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/
View this GCN Circular online at https://gcn.nasa.gov/circulars/36468.
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TITLE: GCN CIRCULAR
NUMBER: 36467
SUBJECT: LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
DATE: 24/05/14 03:32:22 GMT
FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu>
Samuele Ronchini (PSU), Gayathri Raman (PSU), Tyler Parsotan (NASA GSFC), Aaron Tohuvavohu (U Toronto), James DeLaunay (PSU), Jamie A. Kennea (PSU) report:
Swift/BAT was observing 59% of the GW localization probability (Bilby.multiorder.fits) at merger time. A fraction 20% of the GW localization posterior is contained inside the BAT coded FoV.
The LVK notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).
Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.
Using the NITRATES analysis (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), we searched for emission on 8 timescales from 0.128s to 16.384s in the interval [-20,+20] seconds around the merger time. We find no evidence for a signal, and derive the following upper limits.
We quote the 5-sigma flux upper limits in the 15-350 keV band, weighted over the GW localization, for four spectral templates (soft, normal, and hard GRB-like templates described in [arXiv:1612.02395], and spectral shape from GRB170817A [arXiv:1710.05446]) and for four time bins.
In units of 10^-7 erg/s/cm^2:
time_bin (s) soft normal hard GRB170817
------------------------------------
0.256 13.2 8.87 7.95 9.79
1.024 6.71 4.53 4.06 5.00
4.096 3.62 2.44 2.19 2.70
16.384 2.27 1.53 1.37 1.69
The upper limits as function of sky position are plotted here, alongside the GW localization:
https://doi.org/10.5281/zenodo.11188156
The solid and dashed lines indicate the 90% and 50% GW contour levels, respectively. The corresponding fits file is also included.
GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.
A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/
View this GCN Circular online at https://gcn.nasa.gov/circulars/36467.
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