April 2024 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 34199] X-ray transient EP240414a: Detection of associated supernova
by GCN Circulars 30 Apr '24

30 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36355 SUBJECT: X-ray transient EP240414a: Detection of associated supernova DATE: 24/04/30 21:29:28 GMT FROM: Andrew Levan at Radboud University <a.levan(a)astro.ru.nl> A.J. Levan (Radboud), J. van Dalen (Radboud), P. Jonker (Radboud), D.B. Malesani (DAWN/NBI & Radboud), J. Quirola-Vasquez (Radboud), F.E. Bauer (PUC) report for a larger collaboration: We have obtained further monitoring of the counterpart of EP240414a (Lian et al. GCN 36091, Aryan et al. GCN 36094) with the VLT, GTC, SOAR, and NOT. The optical source has decayed to an approximately constant i-band magnitude of i~22 but has declined more rapidly in the g-band, with the g-i colour changing from ~0.4 at four days to g-i~2 at 15 days post-burst. The current magnitudes and colours are consistent with a supernova component now visible in the light curve. Furthermore, an X-shooter spectrum obtained on 25 April 2024 is not the power-law spectrum expected of a GRB afterglow and shows, at low signal-to-noise, features consistent with a broad-lined type Ic supernovae at z~0.4, the redshift of the putative host galaxy (Jonker et al. GCN 36110). Based on the combined light curve and spectral evidence, we suggest that EP240414a is associated with a massive star collapse at a relatively unusual location within its host galaxy. We also note that the peak luminosity and lightcurve shape over the time frame 2-8 days after the transient onset consists of a rise and fall whose shape and luminosity are reminiscent of the fast blue optical transient AT2018cow. However, limited X-ray coverage makes tracking the afterglow behaviour challenging. We thank the staff of the NOT, GTC, SOAR and the VLT for their excellent support. View this GCN Circular online at https://gcn.nasa.gov/circulars/36355. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 34198] LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
by GCN Circulars 30 Apr '24

30 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36354 SUBJECT: LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification DATE: 24/04/30 12:31:30 GMT FROM: Divyajyoti NLN <divyajyoti.nln(a)ligo.org> 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 S240430ca (GCN Circular 36353). 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/S240430ca Based on posterior support from parameter estimation [1], under the assumption that the candidate S240430ca is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [2] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [2] 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%. For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 4045 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 5705 +/- 2109 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] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. (2023) arXiv:2307.13380 [2] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe View this GCN Circular online at https://gcn.nasa.gov/circulars/36354. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 34197] LIGO/Virgo/KAGRA S240430ca: Identification of a GW compact binary merger candidate
by GCN Circulars 30 Apr '24

30 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36353 SUBJECT: LIGO/Virgo/KAGRA S240430ca: Identification of a GW compact binary merger candidate DATE: 24/04/30 10:45:07 GMT FROM: L. Conti at INFN - Padova <livia.conti(a)pd.infn.it> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S240430ca during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2024-04-30 09:35:17.380 UTC (GPS time: 1398504935.380). The candidate was found by the CWB [1] and GstLAL [2] analysis pipelines. S240430ca is an event of interest because its false alarm rate, as estimated by the online analysis, is 7.5e-08 Hz, or about one in 5 months. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S240430ca After parameter estimation by RapidPE-RIFT [3], the classification of the GW signal, in order of descending probability, is BBH (96%), Terrestrial (4%), 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%. [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 4%. 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 [5], distributed via GCN notice about 25 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [5], distributed via GCN notice about 34 seconds 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 5092 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 8573 +/- 2920 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] Rose et al. (2022) arXiv:2201.05263 and Pankow et al. PRD 92, 023002 (2015) doi:10.1103/PhysRevD.92.023002 [4] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [5] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/36353. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 34196] LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
by GCN Circulars 30 Apr '24

30 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36352 SUBJECT: LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations DATE: 24/04/30 03:56:19 GMT FROM: Hyeonho Choi at Seoul National University <hhchoi1022(a)gmail.com> Hyeonho Choi, Myungshin Im , Gregory S.-H. Paek, Seo-Won Chang, Ji Hoon Kim and Hongjae Moon (SNU/SNU ARC), on behalf of the GECKO team We report optical observations conducted with the 7-Dimensional Telescope (7DT) in the ~170 sq. degrees localization area of the LIGO/Virgo/KAGRA gravitational-wave event, S240422ed (The LVK Collaboration, GCN 36236). The 7DT observation started at 01:19:40 UT on 2024-04-23, approximately 3.7 hours after the GW alert. We took a series of r-band images for 3x120 sec per field. The preliminary depth of the combined image is 19.5 magnitudes for a 5-sigma detection of point sources. The coverage of our observations is detailed in TreasureMap (Wyatt et al. 2020): https://treasuremap.space/alerts?graceids=S240422ed Additionally, intensive observations were made in the most probable regions and reported transient candidates with 7DT units equipped with 18 medium-band filters with 25 nm widths from 400 nm to 825 nm at 25 nm intervals. We obtained 0.5 to 2 hours in each medium-band filter, reaching magnitudes of 19-20 for a 5-sigma limiting magnitude. Photometric flux calibration was performed using synthetic photometries derived from the Gaia DR3 XP catalog (Gaia Collaboration et al. 2022) within the AB magnitude system (Gregory S.H. Paek, in prep). Observations at low altitudes resulted in suboptimal conditions, potentially limiting our search sensitivity. Gravitational-wave EM Counterpart Korean Observatory (GECKO) is a network of 0.5m to 1m class telescopes worldwide (Im et al. 2023, Proceedings of IAU Symp. Vol. 363, pp. 207, Paek et al. 2024, ApJ 960 113) including 7DT. 7-Dimensional Telescope (7DT) is a multiple telescope system in Chile to be made of 20 wide-field telescopes equipped with 40 medium-bandwidth (~25nm) filters as well as a suite of broad-band filters when completed. Currently, a partially constructed 7DT made of 10 telescopes with 20 medium-band filters and u, g, r, i, z filters is operational. Further information about the 7DT is available at http://gwuniverse.snu.ac.kr/ . We thank the staff of the ObsTech at the El Sauce observatory for their support of the observation. View this GCN Circular online at https://gcn.nasa.gov/circulars/36352. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 34195] Additional DECam GW-MMADS Candidates from three nights of observations
by GCN Circulars 30 Apr '24

30 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36351 SUBJECT: Additional DECam GW-MMADS Candidates from three nights of observations DATE: 24/04/30 03:04:39 GMT FROM: Igor Andreoni at JSI/UMD/NASA <igor.andreoni(a)gmail.com> Lei Hu (CMU), Tomás Cabrera (CMU), Antonella Palmese (CMU), Igor Andreoni (UMD), Brendan O'Connor (CMU), Keerthi Kunnumkai (CMU) report on behalf of the GW-MMADS team: We report additional candidates from the DECam GW-MMADS survey program (GCN 36245, GCN 36273, GCN 36298, GCN 36317) follow-up of the LIGO/Virgo/KAGRA event S240422ed (GCN 36236, GCN 36240). We ran the SFFT difference imaging (Hu et al. 2022) on the available images from the first three nights of observations (between 2023-04-22 23:37 and 2024-04-25 02:50 UTC), filtered out likely stars and moving objects, and visually inspected the remaining transients. We reported on TNS new transients within the LVK 95% CI area, and report here the additional candidate counterparts with at least two detections and possibly associated with a galaxy. +-------------------------+------------+------------+-----------+-----------+ | id | tns | ra | dec | comment | |-------------------------+------------+------------+-----------+-----------| | T202404240826256m240205 | AT 2024hiw | 126.60656 | -24.03458 | [1] | | T202404240824462m330712 | AT 2024hiu | 126.19269 | -33.12002 | [2] | +-------------------------+------------+------------+-----------+-----------+ [1] ~2.3 arcsec from a galaxy [2] ~3.8 arcsec from a galaxy (possibly from a star on top of a galaxy based on Gaia DR3 and visual inspection) We thank the CTIO and NOIRLab staff for supporting these observations and the data calibrations. View this GCN Circular online at https://gcn.nasa.gov/circulars/36351. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 34194] GRB 240425A: GRBAlpha detection
by GCN Circulars 29 Apr '24

29 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36350 SUBJECT: GRB 240425A: GRBAlpha detection DATE: 24/04/29 20:23:19 GMT FROM: Marianna Dafčíková at Masaryk University <500025(a)mail.muni.cz> M. Dafcikova, J. Ripa, M. Kolar (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Duriskova, L. Szakszonova, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration. The long-duration GRB 240425A (Fermi/GBM detection: GCN 36295; INTEGRAL/SPI-ACS peak detection at 2024-04-25 ~00:21:36 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; https://ui.adsabs.harvard.edu/abs/2023A%26A...677A..40P/abstract) The detection was confirmed at the peak time 2024-04-25 00:21:16.5 UTC. The T90 duration measured by GRBAlpha is 27.5 s and the overall significance during T90 reaches 7.9 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB240425A_GCN.pdf All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. View this GCN Circular online at https://gcn.nasa.gov/circulars/36350. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 34193] Fermi-LAT gamma-ray observations of IceCube-240424A
by GCN Circulars 29 Apr '24

29 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36349 SUBJECT: Fermi-LAT gamma-ray observations of IceCube-240424A DATE: 24/04/29 19:18:19 GMT FROM: Sara Buson at DESY, Univ. of Wurzburg <sara.buson(a)gmail.com> S. Garrappa (Weizmann Institute of Science), C. Bartolini (INFN Bari), S. Buson (Univ. of Wuerzburg), L. Pfeiffer (Univ. of Wuerzburg) and J. Sinapius (DESY) on behalf of the Fermi-LAT collaboration: We report an analysis of observations of the vicinity of the IC240424A high-energy neutrino event (GCN 36283) with all-sky survey data from the Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope. The IceCube event was detected on 2024-04-24 at 01:49:26 UT (T0) with J2000 position RA = 327.08 (+2.06, -1.70) deg, Decl. = +3.06 (+1.37, -1.33) deg (90% PSF containment). Two catalogued gamma-ray (>100 MeV; 4FGL, The Fermi-LAT collaboration 2022, ApJS, 260, 53) sources are located within the 90% IC240204A localization region. These are 4FGL J2149.6+0323 (associated with the FSRQ PKS B2147+031) and 4FGL J2146.8+0425 (associated with the FSRQ MG1 J214653+0427). Based on a preliminary analysis of the LAT data over the timescales of 1-month and 1-day prior to T0, these objects are not significantly detected (> 5 sigma). We searched for intermediate (days to years) timescale emission from a new gamma-ray transient source. Preliminary analysis indicates no significant (> 5 sigma) new excess emission (> 100 MeV) at the IC240424A best-fit position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC240424A best-fit position, the >100 MeV flux upper limit (95% confidence) is < 1.2e-10 ph cm^-2 s^-1 for ~15-years (2008-08-04 to 2024-04-24 UTC), and < 2.2e-8 (<3.2e-8) ph cm^-2 s^-1 for a 1-month (1-day) integration time before T0. In the analysis of the ~15-years integrated LAT data (100 MeV - 1 TeV), a 4.5 sigma new excess of gamma rays, Fermi J2151.3+0220 was detected 1 deg offset from the best-fit IC240424A position and within the 90% confidence localization of the direction of the neutrino. Assuming a power-law spectrum, the best-fit localization is (J2000) RA: 327.83 deg, Dec: 2.34 deg (10 arcmin 99% containment, 5 arcmin 68% containment). The gamma-ray best-fit spectral parameters are flux = (2.5 +/- 1.9)e-9 ph cm^-2 s^-1 and index = 1.7+/-0.2. In a preliminary analysis of the LAT data over 1-day and 1-month prior T0, Fermi J2151.3+0220 is not significantly detected in the LAT data. All values include the statistical uncertainty only. The statistical significance is calculated following the prescription adopted in the 4FGL. Since Fermi normally operates in an all-sky scanning mode, regular monitoring of this region will continue. For these observations the Fermi-LAT contact persons is S. Garrappa (simone.garrappa at weizmann.ac.il). 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/36349. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 34192] LIGO/Virgo/KAGRA S240426s: Updated Sky localization
by GCN Circulars 29 Apr '24

29 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36348 SUBJECT: LIGO/Virgo/KAGRA S240426s: Updated Sky localization DATE: 24/04/29 18:28:27 GMT FROM: Sylvia Biscoveanu at Northwestern CIERA <sylvia.biscoveanu(a)ligo.org> 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 S240426s (GCN Circular 36312). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.offline0.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S240426s For the Bilby.offline0.multiorder.fits,0 sky map, the 90% credible region is 3050 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 3452 +/- 1295 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] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. (2023) arXiv:2307.13380 View this GCN Circular online at https://gcn.nasa.gov/circulars/36348. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 34191] LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
by GCN Circulars 29 Apr '24

29 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36347 SUBJECT: LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a DATE: 24/04/29 18:03:12 GMT FROM: Arne Rau at MPE <arau(a)mpe.mpg.de> Zhu Liu, Arne Rau, Chandreyee Maitra, Pietro Baldini, Andrea Merloni (all MPE), Lorenzo Ducci (IAAT), Mirko Krumpe, Axel Schwope (both AIP): We report constraints on the historical X-ray emission based on archival X-ray observations from the eROSITA X-ray telescope (Predehl et al. A&A 647, A1, 2021) on board the SRG mission for the potential electromagnetic counterpart of the LIGO/Virgo/KAGRA candidate NSBH event S240422ed (GCN 36236) detected by EP/FXT (EP240426a, GCN 36313, GCN 36332). EP240426a was within the Field-of-View of eROSITA during each of the first four eROSITA all-sky surveys (eRASS) conducted between 2019 December and 2021 December. It was not detected in the combined eRASS data (hereafter referred to as eRASS:4). Assuming a power-law model with a photon index of 2.0 and a Galactic column density of 4.33E21 cm^-2 (HI4PI map, N. Ben Bekhti et al., 2016, A&A 594, A116), we derived a 3-sigma X-ray flux upper limit of 1.2E-13 (8.4e-14) erg/s/cm^2 in the 0.5-10.0 (0.2-5.0)keV band, using the eRASS:4 data (total exposure uncorrected for vignetting is approximately 894s). EP240426a was not detected in all individual eRASS scans except for eRASS2, during which a faint source was detected (albeit with a low detection likelihood, e.g. ML_DET = 6.3) with an estimated 0.5-10.0 keV absorbed flux comparable to the derived upper limits. The 3-sigma 0.5-10.0keV flux upper limit derived from eROSITA data is much lower than the flux measured from EP/FXT (absorption-corrected 0.5-10 keV flux of around 9.2E-13 erg/s/cm2, corresponding to an absorbed 0.5-10keV flux of around 6.3E-13 erg/s/cm^2), suggesting that EP240426a showed significant X-ray flux increase. View this GCN Circular online at https://gcn.nasa.gov/circulars/36347. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 34190] LIGO/Virgo/KAGRA S240426dl: Updated Sky localization
by GCN Circulars 29 Apr '24

29 Apr '24

TITLE: GCN CIRCULAR NUMBER: 36346 SUBJECT: LIGO/Virgo/KAGRA S240426dl: Updated Sky localization DATE: 24/04/29 17:52:44 GMT FROM: Sylvia Biscoveanu at Northwestern CIERA <sylvia.biscoveanu(a)ligo.org> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA 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 S240426dl (GCN Circular 36321). 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/S240426dl For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 3469 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 5886 +/- 2242 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] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. (2023) arXiv:2307.13380 View this GCN Circular online at https://gcn.nasa.gov/circulars/36346. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0