February 2025 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 37146] LIGO/Virgo/KAGRA S250204ax: Identification of a GW compact binary merger candidate
by GCN Circulars 04 Feb '25

04 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39137 SUBJECT: LIGO/Virgo/KAGRA S250204ax: Identification of a GW compact binary merger candidate DATE: 25/02/04 06:47:05 GMT FROM: Allen1711449(a)gmail.com The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S250204ax during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2025-02-04 05:52:59.004 UTC (GPS time: 1422683597.004). The candidate was found by the CWB [1], CWB BBH [2], GstLAL [3], PyCBC Live [4], and SPIIR [5] analysis pipelines. S250204ax 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/S250204ax After parameter estimation by RapidPE-RIFT [6], 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%. [7] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [7] 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 [8], distributed via GCN notice about 2 minutes after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [8], distributed via GCN notice about 7 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 814 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2533 +/- 744 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] T. Mishra et al. PRD 105, 083018 (2022) doi:10.1103/PhysRevD.105.083018 [3] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. (2023) arXiv:2305.05625 [4] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [5] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023 [6] Rose et al. (2022) arXiv:2201.05263 and Pankow et al. PRD 92, 023002 (2015) doi:10.1103/PhysRevD.92.023002 [7] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [8] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/39137. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37145] GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
by GCN Circulars 03 Feb '25

03 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39136 SUBJECT: GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection DATE: 25/02/03 20:10:36 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Alan M. Watson (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Sarah Antier (OCA), Rosa L. Becerra (Università degli Studi di Roma Tor Vergata), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Jean-Grégoire Ducoin (CPPM), Francesco Magnani (CPPM), Margarita Pereyra (UNAM), Benjamin Schneider (LAM) and the DDRAGO engineering team: Luis Carlos Álvarez (UNAM), Fernando Angeles, Salvador Cuevas (UNAM), François Dolon (OHP), Alejandro Farah (UNAM), Johan Floriot (LAM), Jorge Fuentes-Fernández (UNAM), Arthur Langios (IRAP), Rosalía Langarica (UNAM), Simona Lombarda (LAM), Jaime Ruíz Díaz-Soto (UNAM), Samuel Ronayette (CEA), Silvio Tinoco (UNAM), and Hervé Valentín (IRAP) report: We imaged the field of the Swift GRB 250129A (Beardmore et al., GCN Circ. 39066) with the COLIBRÍ (SVOM/F-GFT) telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. We observed with the DDRAGO wide-field science camera (Langarica et al., 2024, Proc SPIE 13096, 130963D) in a filter that closely approximates Pan-STARRS r, from 2025-02-03 07:45 to 08:00 UTC, at a midpoint of 5.20 days after the event, and obtained 600 seconds of exposure at a median airmass of 2.25 and good weather conditions. The data were reduced using custom software and then analysed and calibrated against the PS1 catalog using STDPipe (Karpov 2021). We clearly detect the afterglow with r = 22.10 +/- 0.15 This magnitude is not corrected for Galactic extinction. Our measurement is consistent with the magnitude reported by Bochenek & Perley (GCN Circ. 39131) at 4.93 days after the event. Further observations are planned. The DDRAGO camera is still being commissioned, and these are its first science observations. We warmly thank the COLIBRÍ engineering team and the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir. View this GCN Circular online at https://gcn.nasa.gov/circulars/39136. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37144] GRB 250202B: NuSTAR detection of the prompt emission
by GCN Circulars 03 Feb '25

03 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39135 SUBJECT: GRB 250202B: NuSTAR detection of the prompt emission DATE: 25/02/03 19:37:50 GMT FROM: Brian Grefenstette at Caltech/NuSTAR <bwgref(a)srl.caltech.edu> B. Grefenstette (Caltech) reports on behalf of the NuSTAR Search for INteresting Gamma-ray Signals (SINGS) working group: The NuSTAR SINGS working group reports the detection of prompt emission from the Long GRB 250202B in both the NuSTAR CsI anti-coincidence shields. This GRB was identified through a blind search using the CsI shield rates. Details of the search algorithm will be described in a future paper. The NuSTAR SINGS algorithm triggered at 2025-02-02 03:57:12.000 (with a resolution ~5-seconds). This is consistent with the detections by Fermi (Fermi GBM Team, GCN circ. 39120, 39133) and the Astrosat CTZI detection (Waratkar et al, GCN circ. 39122). The NuSTAR CsI shield data are recorded at 1 Hz. The GRB appears to be composed of multiple, significantly-detected peaks, including a second significant set of bursts roughly 90-s after the initial trigger. The total duration for the event is at least 100-s. The largest individual burst peaks at 5,000 cps, with other bursts between 2,000 and 3,000 cps. The baseline rate is a ~1,000 cps during this time period. We do not see a clear signal in the CdZnTe detectors. Using the localization from Fermi at RA = 347.8, Dec = 16.5 implies an offset from the NuSTAR boresight of 115 deg (e.g., through the side of the instrument) and the offset from the geocenter of 114-deg Lightcurves and analysis for this GRB can be found here: https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/reports/2025/250202B/ Information on NuSTAR SINGS can be found here: https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/ NuSTAR is a NASA Small Explorer mission led by Caltech and managed by JPL for NASA’s Science Mission Directorate in Washington. View this GCN Circular online at https://gcn.nasa.gov/circulars/39135. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37143] GRB 250202C: GRBAlpha detection
by GCN Circulars 03 Feb '25

03 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39134 SUBJECT: GRB 250202C: GRBAlpha detection DATE: 25/02/03 17:34:25 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 250202C (Fermi/GBM detection: GCN 39126) 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 2025-02-02 20:10:36.5 UTC. The T90 duration measured by GRBAlpha is 6.0 s and the overall significance during T90 reaches 8.5 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB250202C_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/39134. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37142] GRB 250202B: Fermi GBM Detection
by GCN Circulars 03 Feb '25

03 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39133 SUBJECT: GRB 250202B: Fermi GBM Detection DATE: 25/02/03 17:22:25 GMT FROM: sumanbala2210(a)gmail.com S. Bala (USRA) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 03:57:17.32 UT on 02 February 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250202B (trigger 760161442/250202165). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 347.80, Dec = 16.48 (J2000 degrees, equivalent to J2000 23h 11m, +16d 29'), with a statistical uncertainty of 1.43 degrees. (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a mixture of two Gaussians, one with a radius of 1.8 degrees (52% contribution) and one with a radius of 4.1 degrees (47% contribution) [A. Goldstein et al. 2020, ApJ, 895, 1]). The angle from the Fermi LAT boresight is 128 degrees. The GBM light curve consists of many bright peaks with a duration (T90) of about 89 s (50-300 keV). The time-averaged spectrum from T0-0.1 to T0+109.4 s is best fit by a Band function with Epeak = 252 +/- 5 keV, alpha = -0.81 +/- 0.01, and beta = -2.56 +/- 0.05. The event fluence (10-1000 keV) in this time interval is (1.77 +/- 0.01)E-04 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.7 s in the 10-1000 keV band is 43.4 +/- 0.7 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/39133. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37141] IceCube-250203A - IceCube observation of a high-energy neutrino candidate track-like event
by GCN Circulars 03 Feb '25

03 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39132 SUBJECT: IceCube-250203A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 25/02/03 15:40:47 GMT FROM: A. Zegarelli at Ruhr University Bochum <azegarelli(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 2025-02-03 03:59:29.20 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_Bronze alert stream. The average astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 3.7051 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection. After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/140436_11917698.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 2025-02-03 Time: 03:59:29.20 UT RA: 253.30 (+0.49, -0.49 deg 90% PSF containment) J2000 Dec: -1.31 (+0.48, -0.44 deg 90% PSF containment) J2000 We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino. No known gamma-ray sources listed in the Fermi 4FGL-DR4 or 3FHL catalogs are located within the 90% uncertainty region of the event. 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 View this GCN Circular online at https://gcn.nasa.gov/circulars/39132. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37140] GRB 250129a: Liverpool Telescope optical follow-up
by GCN Circulars 03 Feb '25

03 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39131 SUBJECT: GRB 250129a: Liverpool Telescope optical follow-up DATE: 25/02/03 14:47:32 GMT FROM: A. Bochenek at Liverpool John Moores University <a.m.bochenek(a)2023.ljmu.ac.uk> A. Bochenek and D. A. Perley (LJMU) report: We observed the field of GRB250129a (Beardmore et al., GCN 39066) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 10x90s exposures in the SDSS r’ filter starting at 2025-02-02 02:53:56 UT, approximately 4.93 days after the trigger. We report a detection of the optical transient (Beardmore et al., GCN 39066) in the stacked images of r = 21.80 ± 0.11 mag. Our detection is consistent with other late-time observations (Schlekat et al., GCN39110, Gompertz et al., GCN 39114, Moskvitin et al., GCN39130), and suggests the afterglow is now decaying faster, with a temporal index of approx. -2.2 (fit to observations after 2.5 days post-trigger). The photometry was obtained using nearby PanSTARRS standards and was not corrected for extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/39131. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37139] GRB 240129A: further SAO RAS optical observations
by GCN Circulars 03 Feb '25

03 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39130 SUBJECT: GRB 240129A: further SAO RAS optical observations DATE: 25/02/03 14:10:39 GMT FROM: Moskvitin Alexander at SAO RAS <mosk(a)sao.ru> A. Moskvitin, R. Uklein, Yu. Sotnikova (SAO RAS), A. Ghosh, S. Razzaque (CAPP, University of Johannesburg) report on behalf of the GRB follow-up team. We observed the field of GRB 250129A (Beardmore et al., GCN 39066; Goad et al., GCN 39082; Frederiks et al., GCN 39116) with the SAO RAS 1-m telescope Zeiss-1000 equipped with the multi-mode focal reducer MAGIC on 2025 February 2, 01:23:43--01:43:23 UT (t_mid - T0 = 3.8669 days). We obtained 3 x 300 sec. images in R band. The OT (Francile et al., GCN 39065; GCN 39075, Beardmore et al., GCN 39066, Schneider et al., GCN 39071, Belkin et al., GCN 39072; Izzo et al., GCN 39073; Izzo and Malesani, GCN 39074; Ghosh et al., GCN 39077; Schneider et al., GCN 39078; Brivio et al., GCN 39079; Siegel and Beardmore, GCN 39085; Zheng and Filippenko, GCN 39090; GCN 39102; Schlekat et al., GCN 39091; Antier et al., GCN 39096; Odeh et al., GCN 39097; Ferro et al., GCN 39098; Bochenek and Perley, GCN 39099; Malesani et al., GCN 39100; Romanov, GCN 39101; Watson et al., GCN 39104; Vinko et al., GCN 39105; Akl et al., GCN 39106; Moskvitin et al., GCN 39107; Calapai GCN 39109; Schlekat et al., GCN 39110; Gompertz et al., GCN 39114; Ror et al., GCN 39115; Lipunov et al., GCN 39119; Wu et al., GCN 39124; Paek et al., GCN 39129) is clearly detected in our stacked image with the brightness of R = 21.06 +/- 0.14 (calibrated against R2 magnitudes of nearby UNSO-B1 stars and not corrected for the MW extinction). View this GCN Circular online at https://gcn.nasa.gov/circulars/39130. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37138] GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
by GCN Circulars 03 Feb '25

03 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39129 SUBJECT: GRB 250129A: 7DT Detection and Medium-band SED of Afterglow DATE: 25/02/03 06:14:53 GMT FROM: Gregory Paek at Seoul National University <gregorypaek94(a)gmail.com> Gregory S.H. Paek (IfA, SNU ARC/SNU), Myungshin Im (SNU ARC/SNU), Hyeonho Choi (SNU ARC/SNU), Donggeun Tak (SNU ARC/SNU), Seo-Won Chang (SNU ARC/SNU), and Ji Hoon Kim (SNU ARC/SNU) report on behalf of the 7-Dimensional Telescope collaboration We detected the optical counterpart of GRB 250129A using the 7-Dimensional Telescopes (7DT). Approximately 1 hour and 14 minutes following the initial detection by Swift (Swift team, Beardmore et al., GCN #39066), we targeted the localization center provided by Swift/UVOT at RA, Dec = 198.67673 deg, +5.03063 deg with an uncertainty of 1.10 arcseconds. Observations were made with eleven 7DT units in r-band and nineteen medium-band filters, denoted as m400, m425, then through m875, in which the numeric values indicate their central wavelengths in nanometers. Each medium-band filter has a bandwidth of 25nm. Photometric flux calibration was performed using synthetic photometry based on the Gaia DR3 XP catalog (Gaia Collaboration et al. 2022) within the AB magnitude system. The optical counterpart was detected in most filters. However, only marginal detection was observed in m800, m825, m850, and m875. This is based on preliminary photometry, and no extinction correction has been applied. The 5-sigma upper limits (AB) and detections in relevant filters are summarized below. ------ Filter Mag Mag_err Date-obs[UT] Exp.time[s] Depth(5sigma) Note m425 17.3 0.0 2025-01-29T05:59:21 300 19.9 m450 17.2 0.0 2025-01-29T05:53:51 300 19.2 m475 17.2 0.0 2025-01-29T05:59:21 300 19.5 m500 17.2 0.0 2025-01-29T05:53:51 300 20.0 m525 17.2 0.0 2025-01-29T05:59:20 300 20.1 m550 17.0 0.1 2025-01-29T05:53:52 300 18.6 m575 17.0 0.0 2025-01-29T05:59:19 300 18.8 m600 16.9 0.0 2025-01-29T05:53:58 300 19.7 m625 16.9 0.0 2025-01-29T05:59:36 300 19.4 m650 16.9 0.0 2025-01-29T05:53:56 300 19.4 m675 17.1 0.1 2025-01-29T05:59:22 300 19.4 m700 16.9 0.0 2025-01-29T05:53:49 300 19.2 m725 17.0 0.0 2025-01-29T05:59:17 300 18.9 m750 17.0 0.1 2025-01-29T05:53:54 300 18.8 m775 17.0 0.1 2025-01-29T05:59:22 300 18.3 m800 2025-01-29T05:53:59 300 17.8 n/d m825 2025-01-29T05:59:32 300 17.6 n/d m850 2025-01-29T05:53:54 300 17.2 n/d m875 2025-01-29T05:59:15 300 17.1 n/d r 17.0 0.0 2025-01-29T05:59:07 600 20.9 The 7-Dimensional Telescope (7DT), located in Chile and comprising 20 wide-field telescopes equipped with 40 medium-bandwidth (~25nm) filters, aims to detect optical counterparts of GW sources and conduct the 7-Dimensional Sky Survey (7DS) of the Southern Hemisphere. Further information about the 7DT is available at http://gwuniverse.snu.ac.kr/. View this GCN Circular online at https://gcn.nasa.gov/circulars/39129. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37137] LIGO/Virgo/KAGRA S250202cu: Updated Sky localization
by GCN Circulars 03 Feb '25

03 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39128 SUBJECT: LIGO/Virgo/KAGRA S250202cu: Updated Sky localization DATE: 25/02/03 03:45:53 GMT FROM: lucy.thomas(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 S250202cu (GCN Circular 39125). 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/S250202cu For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 4768 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 5196 +/- 2273 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/39128. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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