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

[vsnet-grb-info 38450] GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
by GCN Circulars 10 May '25

10 May '25

TITLE: GCN CIRCULAR NUMBER: 40419 SUBJECT: GRB 250510B: Swift/BAT-GUANO localization skymap of a burst DATE: 25/05/10 13:48:28 GMT FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu> Samuele Ronchini (PSU), James DeLaunay (PSU), Aaron Tohuvavohu (Caltech), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: Swift/BAT did not localize GRB 250510B onboard (T0: 2025-05-10T06:41:54.06 UTC, Fermi GCN 40418) The Fermi 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. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 11.67 in a 8.192 s analysis time bin, starting at T0 - 2.051 s. Using the NITRATES analysis, parameter estimation was performed to obtain the localization of this burst in the form of a HEALPIX Multi-Order Coverage (MOC) skymap. This localization accounts for both statistical and systematic errors. More details in the creation and calibration of these maps will soon be published (DeLaunay et al. 2025. in prep) The 90% credible area is 9,213 deg2 and the 50% credible area is 2,424 deg2. The integrated probability inside the coded field of view is 4%. The NITRATES skymap is consistent with the Fermi localization (GCN 40418). The combined Fermi/GBM+NITRATES 90% credible area is 550 deg2 and the 50% credible area is 116 deg2. A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=768552149/#:~:te… The probability skymap and joint skymap files can be downloaded from the links here [skymap_fits_file](https://guano.swift.psu.edu/files/768552149/0_n_PROBMAP) [joint_skymap_fits_file](https://guano.swift.psu.edu/files/768552149/0_n_JOI… Instructions on how to read and manipulate this map can be found here: https://guano.swift.psu.edu/documentation More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=768552149 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/40419. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38449] GRB 250510B: Fermi GBM Final Localization
by GCN Circulars 10 May '25

10 May '25

TITLE: GCN CIRCULAR NUMBER: 40418 SUBJECT: GRB 250510B: Fermi GBM Final Localization DATE: 25/05/10 09:49:01 GMT FROM: A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca(a)unitn.it> The Fermi GBM team reports the detection of a likely LONG GRB "At 06:41:54.06 UT on 10 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250510B (trigger 768552119/250510279). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 128.93, Dec = -24.76 (J2000 degrees, equivalent to J2000 08h 35m, -24d 45'), with a statistical uncertainty of 2.39 degrees. The angle from the Fermi LAT boresight is 103 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250510279/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250510279/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250510279/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/40418. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38448] GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
by GCN Circulars 10 May '25

10 May '25

TITLE: GCN CIRCULAR NUMBER: 40417 SUBJECT: GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit DATE: 25/05/10 09:43:41 GMT FROM: Sarah Antier at OCA <sarah.antier(a)oca.eu> Sarah Antier (OCA), Noémie Globus (UNAM), Benjamin Schneider (LAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Fredd Alvarez (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (AUS), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Antonio de Ugarte Postigo (LAM), Y.H. Cheng (SWIFAR,YNU) and B.-T. Wang (YNAO, CAS): We imaged the field of the SVOM GRB 250510A (Cheng et al., GCN Circ. 40415) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2025-05-10 06:02:26 to 06:20:28 UTC (from 1.4 to 1.7 hours after the trigger) and obtained 16 minutes of exposure in the i filter under regular weather conditions. The data were reduced and coadded with the COLIBRÍ pipeline and analyzed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS catalog, is in the AB system, and is not corrected for Galactic extinction. In the stacked image, we do not detect any new source at the ECLAIRs source position (Cheng et al., GCN Circ. 40415) down to the following 5-sigma limit: i > 20.84 Further observations and analysis are ongoing. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/40417. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38447] GRB 250509A: Swift-XRT refined Analysis
by GCN Circulars 10 May '25

10 May '25

TITLE: GCN CIRCULAR NUMBER: 40416 SUBJECT: GRB 250509A: Swift-XRT refined Analysis DATE: 25/05/10 09:02:56 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), S. Dichiara (PSU), J.A. Kennea (PSU), D.N. Burrows (PSU) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 6.8 ks of XRT data for GRB 250509A, from 63 s to 28.3 ks after the trigger. The data comprise 156 s in Windowed Timing (WT) mode (the first 6 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=3.20 (+/-0.09). At T+349 s the decay flattens to an alpha of -1.1 (+0.7, -0.4) before breaking again at T+1377 s to a final decay with index alpha=1.44 (+0.10, -0.09). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.02 (+0.11, -0.10). The best-fitting absorption column is 6.6 (+/-0.7) x 10^21 cm^-2, in excess of the Galactic value of 2.0 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.13 (+/-0.15) and a best-fitting absorption column of 6.0 (+1.0, -0.9) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.1 x 10^-11 (7.5 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 6.0 (+1.0, -0.9) x 10^21 cm^-2 Galactic foreground: 2.0 x 10^20 cm^-2 Excess significance: 10.7 sigma Photon index: 2.13 (+/-0.15) If the light curve continues to decay with a power-law decay index of 1.44, the count rate at T+24 hours will be 9.5 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.9 x 10^-13 (7.1 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01311764. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40416. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38446] GRB 250510A: SVOM possible detection of a burst
by GCN Circulars 10 May '25

10 May '25

TITLE: GCN CIRCULAR NUMBER: 40415 SUBJECT: GRB 250510A: SVOM possible detection of a burst DATE: 25/05/10 05:51:17 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Y.H. Cheng (SWIFAR,YNU), B.-T. Wang (YNAO, CAS), W. J. Xie, D. H. ZHAO (NAO, CAS) on behalf of the SVOM mission team. SVOM/ECLAIRs triggered and located GRB 250510A (SVOM burst-id sb25051002) at 2025-05-10T04:38:52.34 UTC (Tb). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was only detected by the Count-Rate Trigger (CRT), which produced a sequence of 1 alert. CRT provided the alert with the best signal-to-noise-ratio (SNR) of 7.16 in the [20-120] keV energy band over a time window of 10.20 seconds starting at Tb. The localization of the best alert is R.A., Dec. 284.17, 18.37 degrees: R.A. (J2000) = 18h56m41.69s Dec. (J2000) = 18d22m20.68s with a 90% confidence level (C.L.) radius of 10.94 arcmin (including systematic error of 2 arcmin added in quadrature). Due to the trigger SNR less than the slew threshold, no immediate slew was performed on this burst. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. The Burst Advocate (BA) on shift for this burst is Yehao Cheng: yhcheng(a)mail.ynu.edu.cn. Please contact the BA by email if you require additional information regarding the SVOM follow-up of this burst. View this GCN Circular online at https://gcn.nasa.gov/circulars/40415. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38445] GRB 250507A: J-band observations with WINTER
by GCN Circulars 10 May '25

10 May '25

TITLE: GCN CIRCULAR NUMBER: 40414 SUBJECT: GRB 250507A: J-band observations with WINTER DATE: 25/05/10 03:13:29 GMT FROM: Geoffrey Mo at MIT <gmo(a)mit.edu> Geoffrey Mo (MIT), Tomas Ahumada (Caltech), Benjamin Schneider (LAM), Viraj Karambelkar (Caltech), Robert Stein (UMD), Danielle Frostig (CfA), Nathan Lourie (MIT), Robert Simcoe (MIT), and Mansi Kasliwal (Caltech) report: We observed the field of GRB 250507A (Wang et al., GCN 40374) in the near-infrared J-band with the Palomar 1-m telescope, equipped with the 1-square degree WINTER camera (Lourie et al. 2020, Frostig et al. 2024). Observations were triggered automatically and began at 2025-05-09T05:54:11 UTC (1.97 days after the GRB), consisting of 15 x 120 s exposures. The images were processed using the WINTER data reduction pipeline implemented with mirar (https://github.com/winter-telescope/mirar, https://doi.org/10.5281/zenodo.13352565). We do not detect any uncataloged sources in the SVOM/MXT (Wang et al., GCN 40374; Maggi et al., GCN 40381), EP-FXT (Zhang et al., GCN 40385), or Swift-XRT (Osborne et al., GCN 40389) localizations after visual comparison to archival PanSTARRS-1 (Chambers et al. 2016) y-band imaging. This is consistent with observations by Ducoin et al., GCN 40376; Xin et al., GCN 40379; Brivio et al., GCN 40380; and Zheng et al., GCN 40400. We obtain the following 5-sigma upper limit: J ~ 19.5 mag (AB). WINTER (Wide-field INfrared Transient ExploreR) is a partnership between MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AAG, the David and Lucile Packard Foundation, and the MIT Kavli Institute for Astrophysics and Space Research. View this GCN Circular online at https://gcn.nasa.gov/circulars/40414. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38444] GRB 250507A: J-band observations with WINTER
by GCN Circulars 10 May '25

10 May '25

TITLE: GCN CIRCULAR NUMBER: 40413 SUBJECT: GRB 250507A: J-band observations with WINTER DATE: 25/05/10 03:12:44 GMT FROM: Geoffrey Mo at MIT <gmo(a)mit.edu> Geoffrey Mo (MIT), Tomas Ahumada (Caltech), Benjamin Schneider (LAM), Viraj Karambelkar (Caltech), Robert Stein (UMD), Danielle Frostig (CfA), Nathan Lourie (MIT), Robert Simcoe (MIT), and Mansi Kasliwal (Caltech) report: We observed the field of GRB 250507A (Wang et al., GCN 40374) in the near-infrared J-band with the Palomar 1-m telescope, equipped with the 1-square degree WINTER camera (Lourie et al. 2020, Frostig et al. 2024). Observations were triggered automatically and began at 2025-05-09T05:54:11 UTC (1.97 days after the GRB), consisting of 15 x 120 s exposures. The images were processed using the WINTER data reduction pipeline implemented with mirar (https://github.com/winter-telescope/mirar, https://doi.org/10.5281/zenodo.13352565). We do not detect any uncataloged sources in the SVOM/MXT (Wang et al., GCN 40374; Maggi et al., GCN 40381), EP-FXT (Zhang et al., GCN 40385), or Swift-XRT (Osborne et al., GCN 40389) localizations after visual comparison to archival PanSTARRS-1 (Chambers et al. 2016) y-band imaging. This is consistent with observations by Ducoin et al., GCN 40376; Xin et al., GCN 40379; Brivio et al., GCN 40380; and Zheng et al., GCN 40400. We obtain the following 5-sigma upper limit: J ~ 19.5 mag (AB). WINTER (Wide-field INfrared Transient ExploreR) is a partnership between MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AAG, the David and Lucile Packard Foundation, and the MIT Kavli Institute for Astrophysics and Space Research. View this GCN Circular online at https://gcn.nasa.gov/circulars/40413. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38443] GRB 250507A: J-band observations with WINTER
by GCN Circulars 10 May '25

10 May '25

TITLE: GCN CIRCULAR NUMBER: 40413 SUBJECT: GRB 250507A: J-band observations with WINTER DATE: 25/05/10 03:12:44 GMT FROM: Geoffrey Mo at MIT <gmo(a)mit.edu> Geoffrey Mo (MIT), Tomas Ahumada (Caltech), Benjamin Schneider (LAM), Viraj Karambelkar (Caltech), Robert Stein (UMD), Danielle Frostig (CfA), Nathan Lourie (MIT), Robert Simcoe (MIT), and Mansi Kasliwal (Caltech) report: We observed the field of GRB 250507A (Wang et al., GCN 40374) in the near-infrared J-band with the Palomar 1-m telescope, equipped with the 1-square degree WINTER camera (Lourie et al. 2020, Frostig et al. 2024). Observations were triggered automatically and began at 2025-05-09T05:54:11 UTC (1.97 days after the GRB), consisting of 15 x 120 s exposures. The images were processed using the WINTER data reduction pipeline implemented with mirar (https://github.com/winter-telescope/mirar, https://doi.org/10.5281/zenodo.13352565). We do not detect any uncataloged sources in the SVOM/MXT (Wang et al., GCN 40374; Maggi et al., GCN 40381), EP-FXT (Zhang et al., GCN 40385), or Swift-XRT (Osborne et al., GCN 40389) localizations after visual comparison to archival PanSTARRS-1 (Chambers et al. 2016) y-band imaging. This is consistent with observations by Ducoin et al., GCN 40376; Xin et al., GCN 40379; Brivio et al., GCN 40380; and Zheng et al., GCN 40400. We obtain the following 5-sigma upper limit: J ~ 19.5 mag (AB). WINTER (Wide-field INfrared Transient ExploreR) is a partnership between MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AAG, the David and Lucile Packard Foundation, and the MIT Kavli Institute for Astrophysics and Space Research. View this GCN Circular online at https://gcn.nasa.gov/circulars/40413. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38442] EP250508a: SVOM/VT optical candidate fading
by GCN Circulars 10 May '25

10 May '25

TITLE: GCN CIRCULAR NUMBER: 40412 SUBJECT: EP250508a: SVOM/VT optical candidate fading DATE: 25/05/10 01:53:50 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Z. H. Yao, Y. N. Ma, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei, T. Zhao, R. D. Liang, H. Q. Cheng, W. D. Zhang (NAOC, CAS), Y. D. Hu (GXU), L. Zhang (IHEP), X. L. Chen(YNU) report on behalf of the SVOM and EP Teams: SVOM/VT made a second ToO observation for EP250508a (Liang et al., GCN 40390，Zhao et al., GCN 40399) at about 29.44 hour after trigger. The observation was performed in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. The brightness of the candidate reported by Xin et al. (GCN 40402) was VT_R=23.9+/-0.3 mag and VT_B>24.0 with the exposure time of 52*100 seconds. Our photometry was derived in AB magnitude and not corrected for Galactic extinction. Considering the fading behavior of the candidate, we suggest that it is the optical counterpart of the transient. 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. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC),CAS. View this GCN Circular online at https://gcn.nasa.gov/circulars/40412. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38441] GRB 250509A: Enhanced Swift-XRT position
by GCN Circulars 10 May '25

10 May '25

TITLE: GCN CIRCULAR NUMBER: 40411 SUBJECT: GRB 250509A: Enhanced Swift-XRT position DATE: 25/05/10 01:51:55 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 877 s of XRT Photon Counting mode data and 2 UVOT images for GRB 250509A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 46.44965, -38.84201 which is equivalent to: RA (J2000): 03h 05m 47.92s Dec (J2000): -38d 50' 31.2" with an uncertainty of 2.3 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40411. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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