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

[vsnet-grb-info 37798] GRB 250319A: Fermi GBM Final Localization
by GCN Circulars 19 Mar '25

19 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39782 SUBJECT: GRB 250319A: Fermi GBM Final Localization DATE: 25/03/19 15:14:51 GMT FROM: rhamburg(a)usra.edu The Fermi GBM team reports the detection of a likely LONG GRB "At 04:52:59.46 UT on 19 March 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250319A (trigger 764052784/250319203). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 335.24, Dec = -62.32 (J2000 degrees, equivalent to J2000 22h 21m, -62d 19'), with a statistical uncertainty of 6.84 degrees. The angle from the Fermi LAT boresight is 25 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250319203/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250319203/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250319203/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/39782. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37797] GRB250317D: EIRSAT-1 GMOD Detection
by GCN Circulars 19 Mar '25

19 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39781 SUBJECT: GRB250317D: EIRSAT-1 GMOD Detection DATE: 25/03/19 14:00:39 GMT FROM: Caimin McKenna at University College Dublin <caimin.mckenna(a)ucdconnect.ie> C. McKenna, D. Murphy, C. de Barra, A. Ulyanov, P. McDermott, G. Finneran, M. Doyle, R. Dunwoody, J. Mangan, G. Corcoran, L. Cotter, A. Empey, J. Fisher, F. Gibson Kiely, J. Thompson, D. McKeown, A. Martin-Carrillo, L. Hanlon, S. McBreen, on behalf of the EIRSAT-1 team: EIRSAT-1 reports the detection of the long gamma-ray burst GRB250317D by the Gamma-ray Module (GMOD) instrument, which also triggered Fermi GBM (Fermi Trigger 763933627 / bn250317824, retrieved from Fermi GBM burst catalog [von Kienlin, A. et al. 2020, Gruber, D. et al. 2014, von Kienlin, A. et al. 2014, and Bhat, P. et al. 2016]) The GMOD detection was made starting at 2025-03-17 19:47:53.5 UTC. The GMOD light-curve for GRB250317D with 1.2s binning shows a bright pulse starting at 19:47:53.5 UTC, also visible on the Fermi light-curve, followed by a less significant second pulse of one bin width. The pulses seen earlier than this time in the Fermi light-curve cannot be distinguished against the background in the GMOD light-curve. The spacecraft location at the time of detection was 17.359 N, 35.838 E, at an altitude of 414.30 km. The GMOD light curve for this event can be found here: https://grb.eirsat1.ie/250317D/250317D_LC_onboard_preliminary.png EIRSAT-1 is Ireland’s first satellite (Doyle et al. Proceedings of the 4th SSEA, 2022). It is a 2U CubeSat and carries onboard a number of experiments including the Gamma-Ray Module (GMOD), a novel, compact, gamma-ray detector (Murphy et al, Experimental Astronomy, 53, 961–990, 2022). GMOD consists of a 25 mm × 25 mm × 40 mm Cerium Bromide scintillator coupled to SiPMs and is designed to detect gamma-ray bursts in the ~ 60 keV - 1.5 MeV range. EIRSAT-1 was developed in University College Dublin with support from ESA’s Fly Your Satellite! programme and was launched on 1st December 2023. View this GCN Circular online at https://gcn.nasa.gov/circulars/39781. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37796] LIGO/Virgo/KAGRA S250319bu: Updated Sky localization
by GCN Circulars 19 Mar '25

19 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39780 SUBJECT: LIGO/Virgo/KAGRA S250319bu: Updated Sky localization DATE: 25/03/19 13:55:10 GMT FROM: Aditya Vijaykumar <aditya.vijaykumar(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 S250319bu (GCN Circular 39776). 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/S250319bu For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 989 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 4713 +/- 1546 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. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/39780. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37795] GRB 250314A: ATCA radio upper limits
by GCN Circulars 19 Mar '25

19 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39779 SUBJECT: GRB 250314A: ATCA radio upper limits DATE: 25/03/19 13:49:11 GMT FROM: Tao An at SHAO, CAS <antao(a)shao.ac.cn> Tao An, Yuanqi Liu, Kexuan Chong (SHAO), Jinjun Geng, Xuefeng Wu (PMO), report on behalf of a large collaboration: We have conducted radio observations of the high-redshift gamma-ray burst GRB 250314A (GCN 39719, 39729; redshift z ~ 7.3, GCN 39732, 39743) using the Australia Telescope Compact Array (ATCA). Our observations were performed on 2025 March 15, from UT 13:00 to 19:00, simultaneously at central frequencies of 5.5 GHz and 9 GHz. The achieved 1-sigma image rms noise levels are approximately 13 microJy/beam at 5.5 GHz and 9 microJy/beam at 9 GHz. At the position of the potential optical counterpart reported in GCN 39727, we find no significant radio emission above a 3-sigma threshold at either frequency. We thank Jamie Stevens for his rapid response in scheduling these observations. We thank the CSIRO Space and Astronomy staff for supporting these observations. The Australia Telescope Compact Array is part of the Australia Telescope National Facility which is funded by the Australian Government for operation as a National Facility managed by CSIRO. View this GCN Circular online at https://gcn.nasa.gov/circulars/39779. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37794] EP250302a: VLA observations
by GCN Circulars 19 Mar '25

19 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39778 SUBJECT: EP250302a: VLA observations DATE: 25/03/19 11:45:41 GMT FROM: Tao An at SHAO, CAS <antao(a)shao.ac.cn> Ailing Wang (IHEP), Tao An (SHAO), Cuiyuan Dai and Xiangyu Wang (NJU), report on behalf of a larger collaboration: We report radio observations of EP250302a (GCN 39556) conducted with the Karl G. Jansky Very Large Array (VLA) on 2025 March 15, UT02:17-03:38 (approximately T0+13 days after the initial trigger). Observations were carried out across three frequency bands (Ku/X/C bands). The preliminary results show 4-4.5 sigma detection at the position reported by X-ray and optical observations (e.g., GCN 39550, 39557). The image noise ranges from 6.4 to 10 microJy/beam. The source exhibits a relatively flat spectrum between 4 and 18 GHz. Follow-up VLA observations are planned to verify the detection and trace the flux density evolution. View this GCN Circular online at https://gcn.nasa.gov/circulars/39778. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37793] GRB 250317B: OHP/T193 continued follow-up
by GCN Circulars 19 Mar '25

19 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39777 SUBJECT: GRB 250317B: OHP/T193 continued follow-up DATE: 25/03/19 08:16:18 GMT FROM: Emeric Le Floc'h at CEA-Saclay <emeric.lefloch(a)cea.fr> B. Schneider (LAM), C. Adami (LAM/Pytheas/AMU), E. Le Floc'h (CEA/Irfu), A. Ugarte Postigo (LAM), M. Dennefeld (IAP/CNRS/Sorbonne U.) and D. Turpin (CEA/Irfu) report on behalf of the MISTRAL-GRB collaboration: We performed additional observations of the optical counterpart of GRB 250317B (Zhao et al., GCN 39753; Watson et al., GCN 39754; Palmerio et al., GCN 39755; Pérez-Fournon et al., GCN 39757; Ghosh et al., GCN 39759, Ferro et al., GCN 39764, Schneider et al., GCN 39767; Thöne et al., GCN 39769; Zhu et al., GCN 39770; Pankov et al., GCN 39772; Moretti et al., GCN 39774) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. We obtained 1 exposure of 600s and 5 exposures of 720s in the r-band starting at 19:22 UT on 2025-03-18 (1.84 days after the trigger). In the final stacked image, the afterglow is marginally detected, at a level much fainter than the phase of rebrightening reported earlier by Thöne et al. (GCN 39769) and Zhu et al. (GCN 39770). The preliminary magnitude derived for the source is : r = 23.5 +/- 0.4 mag (AB) The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitudes are not corrected for Galactic extinction. We acknowledge the excellent support from the Observatoire de Haute-Provence and in particular Jean Balcaen et Andres Carmona for the MISTRAL observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/39777. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37792] LIGO/Virgo/KAGRA S250319bu: Identification of a GW compact binary merger candidate
by GCN Circulars 19 Mar '25

19 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39776 SUBJECT: LIGO/Virgo/KAGRA S250319bu: Identification of a GW compact binary merger candidate DATE: 25/03/19 07:43:35 GMT FROM: sreedevi_p230198ph(a)nitc.ac.in The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S250319bu during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2025-03-19 06:25:36.479 UTC (GPS time: 1426400754.479). The candidate was found by the GstLAL [1], MBTA [2], and SPIIR [3] analysis pipelines. S250319bu is an event of interest because its false alarm rate, as estimated by the online analysis, is 4.7e-10 Hz, or about one in 67 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S250319bu The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%). The LIGO Hanford detector lost its working point about two seconds after the merger time. That has been carefully investigated by the LVK rapid response team and should have no impact on the significance of the signal nor on its classification or skymap. 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%. [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 for maximum neutron star mass. 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 [5], distributed via GCN notice about 23 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [5], distributed via GCN notice about 28 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 2057 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 4372 +/- 1308 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. PRD 109, 042008 (2024) doi:10.1103/PhysRevD.109.042008 [2] Aubin et al. CQG 38, 095004 (2021) doi:10.1088/1361-6382/abe913 [3] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023 [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/39776. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37791] GRB 250317C: SVOM/GRM observation of a long burst
by GCN Circulars 19 Mar '25

19 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39775 SUBJECT: GRB 250317C: SVOM/GRM observation of a long burst DATE: 25/03/19 02:11:00 GMT FROM: Yue Wang <m18509381757(a)163.com> SVOM/GRM team: Yue Wang, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Tais Maiolino, Frédéric Piron (LUPM), Stéphane Schanne (CEA), Jean-Luc Atteia (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by GRB 250317C (SVOM trigger reference: sb25031702) at 2025-03-17T17:31:28.000 (T0). This burst was also detected by GECAM-B and AstroSat CZTI (Wang et al., GCN 39768; S. Salunke et al., GCN 39771). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of single main pulse with a T90 of 23.4 +3.7/-2.0 s in the 15-5000 keV band. In addition, ECLAlRs was taking data and did not trigger, since the position of this burst, as determined by GECAM-B (GCN 39768, RA: 320.42 deg, DEC: -16.07 deg, Error: 8.59 deg), is located at about 108.3 degrees from the SVOM optical axis, and outside the ECLAIRs field of view. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250317C.png The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM/GRM point of contact for this burst is: Yue Wang (IHEP) (yuewang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/39775. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37790] GRB 250317B: Leavitt Observatory optical upper limit
by GCN Circulars 18 Mar '25

18 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39774 SUBJECT: GRB 250317B: Leavitt Observatory optical upper limit DATE: 25/03/18 20:04:16 GMT FROM: leavittob(a)gmail.com L. Moretti, E. Pavoni (Leavitt Observatory, Italy) Members of: GRB/UAI - Gamma Ray Burst Section of Unione Astrofili Italiani ATA - Associazione Tuscolana di Astronomia In a large collaboration with: M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy), K. Kalinowski (Aarhus University, Department of Physics and Astronomy), report: We observed the field of the GRB 250317B triggered by SVOM/ECLAIRs (Zhao et al., GCN 39752 and GCN 39753) and SVOM/MXT (Zhao et al., GCN 39752 and GCN 39753; and Götz et al., GCN 39756) with our RC telescope (D=250 mm, F/D=8) of Leavitt Observatory, Manciano, Italy. The observations started approximately 19 hours after the SVOM/ECLAIRs trigger time, with good weather conditions, stacking a set of unfiltered FITS frames. Images were processed using the astropy package (Astropy Collaboration et al., 2022ApJ...935..167A). In the stacked frame, we did not found any optical uncatalogued object within the SVOM error circle. Mid-Time (UTC) Limit (clear filter) Error 2025-03-17T21:18:03 >20.0 +/- 0.1 Magnitudes were estimated with the BP-band of Gaia DR3 catalogue (*) and are not corrected for galactic dust extinction. The message may be cited. Reference: https://leavittobservatory.altervista.org (*) https://gea.esac.esa.int/archive/documentation/GEDR3/Data_processing/chap_c… View this GCN Circular online at https://gcn.nasa.gov/circulars/39774. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37789] GRB 250309B/AT2025dws: further ATCA observations
by GCN Circulars 18 Mar '25

18 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39773 SUBJECT: GRB 250309B/AT2025dws: further ATCA observations DATE: 25/03/18 17:15:37 GMT FROM: James Leung at U. Toronto / HUJI <jamesk.leung(a)utoronto.ca> J. K. Leung (U. Toronto/HUJI), G. E. Anderson (Curtin University), A. J. van der Horst (GWU), L. Rhodes (TSI/McGill), Maria Drout (U. Toronto), Andrew Hughes (U. Oxford) report on behalf of a larger collaboration: We report a second epoch of Australia Telescope Compact Array (ATCA) radio observations centred in the direction of the candidate optical counterpart AT2025dws (Stein et al., GCN 29639; Pérez-Fournon et al., GCN 29643; Alexander et al., GCN39645; Stein et al, GCN 39644; Perley et al. GCN 39646; Wang et al., GCN 39648; Ducoin et al., GCN 39650; Shin et al., GCN 39654) to GRB 250309B (Preis and Greiner, GCN 39629; McDermott et al., GCN 39642; Page and Evans, GCN 39649; Kozyrev et al., GCN 29652; and Frederiks et al., GCN 39655). These observations follow an earlier detection of the radio counterpart by the ATCA (An et al., GCN 39699). The observations were taken at a mean epoch of UT12:57 on 2025-03-13T12:57 at central frequencies 5.5, 9, and 16.7 GHz. In our preliminary analysis, we detect a clear radio source at the position of the candidate optical and radio counterparts in both the 5.5 and 9 GHz images (0.24+/-0.04 mJy and 0.30+/-0.03 mJy, respectively) and attain a 5-sigma non-detection limit of <0.45 mJy/beam at 16.7 GHz. We thank the CSIRO Space and Astronomy staff for supporting these observations. We acknowledge the Gomeroi people as the traditional owners of the Observatory site. The Australia Telescope Compact Array is part of the Australia Telescope National Facility (https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO. View this GCN Circular online at https://gcn.nasa.gov/circulars/39773. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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