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

[vsnet-grb-info 37918] LIGO/Virgo/KAGRA S250328ae: Updated Sky localization
by GCN Circulars 28 Mar '25

28 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39900 SUBJECT: LIGO/Virgo/KAGRA S250328ae: Updated Sky localization DATE: 25/03/28 08:07:05 GMT FROM: Aaron Zimmerman at U. of Texas at Austin <aaron.zimmerman(a)utexas.edu> 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 (… [View More]

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[vsnet-grb-info 37917] GRB 250327A: SVOM/VT upper limits on the XRT position
by GCN Circulars 28 Mar '25

28 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39899 SUBJECT: GRB 250327A: SVOM/VT upper limits on the XRT position DATE: 25/03/28 06:44:48 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> H.L. Li(NAOC), L. Zhang (IHEP), Y.D. Hu (GXU), X.L. Chen (YNU), Y. L. Qiu, L.P. Xin, C. Wu, Z.H. Yao, Y. Xu, P.P. Zhang, J. Wang, Y.N. Ma, X.H. Han, H.B. Cai, W. J. Xie, J.Y. Wei (NAOC), J. T. Palmerio (CEA)report on behalf of the SVOM/VT team: SVOM performed a Target of Opportunity observation of GRB 250327A (… [View More]

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[vsnet-grb-info 37916] LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
by GCN Circulars 28 Mar '25

28 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39898 SUBJECT: LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate DATE: 25/03/28 06:27:04 GMT FROM: Sayantan Ghosh at Indian Institute of Technology Bombay <stanghosh(a)iitb.ac.in> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S250328ae during real-time processing of data from LIGO Hanford Observatory (H1), LIGO … [View More]Livingston Observatory (L1), and Virgo Observatory (V1) at 2025-03-28 05:40:27.419 UTC (GPS time: 1427175645.419). The candidate was found by the cWB [1], cWB BBH [2], GstLAL [3], MBTA [4], MLy [5], PyCBC Live [6], and SPIIR [7] analysis pipelines. S250328ae 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/S250328ae After parameter estimation by RapidPE-RIFT [8], 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 at least one of the compact objects is consistent with a neutron star mass (HasNS) is <1%. [9] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [9] Both HasNS and HasRemnant consider the support of several neutron star equations of state for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is 7%. 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 [10], distributed via GCN notice about 32 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [10], 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 well fit by an ellipse with an area of 22 deg2 described by the following DS9 region (right ascension, declination, semi-major axis, semi-minor axis, position angle of the semi-minor axis): icrs; ellipse(09h39m, +10d34m, 7.42d, 0.95d, 115.70d) Marginalized over the whole sky, the a posteriori luminosity distance estimate is 492 +/- 91 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. PRD 109, 042008 (2024) doi:10.1103/PhysRevD.109.042008 [4] Aubin et al. CQG 38, 095004 (2021) doi:10.1088/1361-6382/abe913 [5] Skliris et al. (2020) arXiv:2009.14611 [6] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [7] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023 [8] Rose et al. (2022) arXiv:2201.05263 and Pankow et al. PRD 92, 023002 (2015) doi:10.1103/PhysRevD.92.023002 [9] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [10] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/39898. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37915] GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
by GCN Circulars 28 Mar '25

28 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39897 SUBJECT: GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations DATE: 25/03/28 06:11:29 GMT FROM: J.-G. Ducoin at CPPM <ducoin(a)cppm.in2p3.fr> Jean-Grégoire Ducoin (CPPM), Enrique Moreno Méndez (UNAM), Stéphane Basa (LAM), William H. Lee (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Sarah Antier (OCA), Jean-Luc Atteia (IRAP), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Ramandeep Gill (… [View More]

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[vsnet-grb-info 37914] GRB 250327B: Las Cumbres optical counterpart detection
by GCN Circulars 28 Mar '25

28 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39896 SUBJECT: GRB 250327B: Las Cumbres optical counterpart detection DATE: 25/03/28 04:43:23 GMT FROM: Manisha Shrestha at University of Arizona <mshrestha1(a)arizona.edu> M. Shrestha (Univ. of Arizona), D. Sand (Univ. of Arizona), K. D. Alexander (Univ. of Arizona), J. Andrews (Gemini), J. Pearson (Univ. of Arizona), N. Smith (Univ. of Arizona), K. Bostroem (Univ. of Arizona), C. Christy (Univ. of Arizona), N. Franz (Univ. of Arizona), D. A. Howell (… [View More]

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[vsnet-grb-info 37913] GRB 250327B: Swift-XRT detection of the X-ray afterglow
by GCN Circulars 28 Mar '25

28 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39895 SUBJECT: GRB 250327B: Swift-XRT detection of the X-ray afterglow DATE: 25/03/28 03:39:17 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> K.L. Page, P.A. Evans (U. Leicester) and C.A. Gronwall (PSU) report on behalf of the Swift-XRT Team On 2025 March 27 at 21:35 UT, Swift began a Target-of-Opportunity observation of the SVOM-discovered burst GRB 250327B (GCN Circ. 39888). 750 s of data were collected, starting 1.7 ks after the SVOM/… [View More]

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[vsnet-grb-info 37912] GRB 250327B: 1.6m Mephisto optical observations
by GCN Circulars 28 Mar '25

28 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39894 SUBJECT: GRB 250327B: 1.6m Mephisto optical observations DATE: 25/03/28 01:40:32 GMT FROM: Brajesh Kumar at SWIFAR, YNU <brajesh(a)ynu.edu.cn> Jianhui Lian, Brajesh Kumar, Xufeng Zhu, Fanchuan Kong, Yaosong Yu, Yu Pan, Guowang Du, Xingzhu Zou, Yuan Fang, Xinzhong Er, Jinghua Zhang, Tao Wang, Xinlei Chen, Helong Guo, Xiangkun Liu, Xiaowei Liu (all SWIFAR, YNU) report on behalf of the Mephisto Team: The field of SVOM GRB 250327B (Bouchet et al., … [View More]

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[vsnet-grb-info 37911] GRB 250327B: NOT spectroscopic redshift z = 3.035
by GCN Circulars 28 Mar '25

28 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39893 SUBJECT: GRB 250327B: NOT spectroscopic redshift z = 3.035 DATE: 25/03/28 00:17:12 GMT FROM: Daniele B. Malesani at IMAPP / Radboud University <d.malesani(a)astro.ru.nl> D. B. Malesani (DAWN/NBI and Radboud), B. Schneider (LAM), A. Martin-Carrillo (UCD), J. T. Palmerio (CEA/Irfu), G. Corcoran (UCD), B. Gompertz (Birmingham), A. de Ugarte Postigo (LAM), T. Pursimo (NOT), report on behalf of a larger collaboration: We observed the optical … [View More]

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[vsnet-grb-info 37910] GRB 250327A: Swift-XRT refined Analysis
by GCN Circulars 28 Mar '25

28 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39892 SUBJECT: GRB 250327A: Swift-XRT refined Analysis DATE: 25/03/28 00:07:39 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> D.N. Burrows (PSU), M. A. Williams (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 8.0 ks of XRT data for GRB 250327A, from … [View More]

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[vsnet-grb-info 37909] GRB 250327B: GOTO optical counterpart detection
by GCN Circulars 27 Mar '25

27 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39891 SUBJECT: GRB 250327B: GOTO optical counterpart detection DATE: 25/03/27 23:19:12 GMT FROM: d.s.oneill(a)bham.ac.uk D. O’Neill, A. Kumar, B. Godson, B. P. Gompertz, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, K. Ulaczyk, F. Jimenez-Ibarra, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien, G. Ramsay, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, E. Palle and D. Pollacco report on behalf of the GOTO collaboration: We report on observations with … [View More]the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al. 2024) in response to the SVOM/ECLAIRS sb2503270 (Bouchet et al. 39888). The observations were conducted between 2025-03-27 21:14:55 (208 sec post-trigger) and 2025-03-27 22:24:37.72 (76.42 min post-trigger). Each observation consisted of 4x90s exposures in the GOTO L-band (400-700 nm). Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations of the same pointings. We detect the optical counterpart reported by SAO RAS and SVOM/VT (Moskvitin et al., GCN 39889; Xin et al., GCN 39890) as an initially rising source that reached a peak magnitude of L=15.098 ± 0.012 at 8.43 min after trigger, before decaying at a rate of approximately t^-0.8 to a magnitude of 17.011 ± 0.004 at t0+76.42 min post-trigger. We find no evidence of the source prior to the GRB trigger time in previous GOTO observations, the ZTF observations provided by the Lasair broker (Smith et al. 2019), or the ATLAS forced photometry server (Shingles et al. 2021). Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction. Observations are ongoing. GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC). View this GCN Circular online at https://gcn.nasa.gov/circulars/39891. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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