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

[vsnet-grb-info 40344] GRB 251014A: VLT/FORS2 Optical Observation
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42270 SUBJECT: GRB 251014A: VLT/FORS2 Optical Observation DATE: 25/10/14 21:28:42 GMT FROM: Roberto Ricci at INAF-IRA <ricci(a)ira.inaf.it> Muskan Yadav (U Rome), Roberto Ricci (U Rome), Yu-Han Yang (U Rome), Rosa L. Becerra (U Rome) and Eleonora Troja (U Rome) report on behalf of the ERC BHianca team: We observed the field of GRB 251014A detected by Fermi (Fermi Team et al., GCN 42237) and Swift/BAT (Ambrosi et al., GCN 42238) with the FORS2 imager on the ESO VLT UT1 (Antu). Observations began 7.55 hours after the trigger and were carried out in the R filter with an average airmass of ~1.5. Having no reference image deep enough to compare with our science image, at this stage we are not able to determine whether there are new sources down to the limiting magnitude probed by FORS2. Further observations or an arcsec X-ray counterpart are required to make such a claim. We thank the staff at the VLT for the rapid execution of these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42270. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40343] GRB 251014C: Fermi GBM Final Localization
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42272 SUBJECT: GRB 251014C: Fermi GBM Final Localization DATE: 25/10/14 21:48:07 GMT FROM: Suman Bala at USRA <sumanbala2210(a)gmail.com> The Fermi GBM team reports the detection of a likely LONG GRB "At 20:45:58.96 UT on 14 October 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251014C (trigger 782167563/251014865). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 133.36, Dec = 14.24 (J2000 degrees, equivalent to J2000 8h 53m, +14d 14'), with a statistical uncertainty of 5.09 degrees. The angle from the Fermi LAT boresight is 84 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251014865/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251014865/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251014865/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/42272. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40342] GRB 251014A: Glowbug gamma-ray detection of a likely short burst
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42271 SUBJECT: GRB 251014A: Glowbug gamma-ray detection of a likely short burst DATE: 25/10/14 21:37:02 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil> R. Woolf, C.C. Cheung, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 251014A, which was also detected by Fermi/GBM (GCN 42237, 42249) and Swift/BAT (GCN 42238). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-10-14 00:28:30.032 with a duration of 1.02 s and a total significance of about 9.9 sigma. The light curve is dominated by a single peak. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS, and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42271. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40341] GRB 250821A: VLT/FORS2 Optical Observation
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42270 SUBJECT: GRB 250821A: VLT/FORS2 Optical Observation DATE: 25/10/14 21:28:42 GMT FROM: Roberto Ricci at INAF-IRA <ricci(a)ira.inaf.it> Muskan Yadav (U Rome), Roberto Ricci (U Rome), Yu-Han Yang (U Rome), Rosa L. Becerra (U Rome) and Eleonora Troja (U Rome) report on behalf of the ERC BHianca team: We observed the field of GRB 251014A detected by Fermi (Fermi Team et al., GCN 42237) and Swift/BAT (Ambrosi et al., GCN 42238) with the FORS2 imager on the ESO VLT UT1 (Antu). Observations began 7.55 hours after the trigger and were carried out in the R filter with an average airmass of ~1.5. Having no reference image deep enough to compare with our science image, at this stage we are not able to determine whether there are new sources down to the limiting magnitude probed by FORS2. Further observations or an arcsec X-ray counterpart are required to make such a claim. We thank the staff at the VLT for the rapid execution of these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42270. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40340] GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42269 SUBJECT: GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart DATE: 25/10/14 20:51:20 GMT FROM: Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy - MPC Code C82 <osservatorionastroverde(a)gmail.com> Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy in a large collaboration with: M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy) and K. Kalinowski (Aarhus University, Department of Physics and Astronomy) report: Following the circular GCN 42222, in which N. A. Rakotondrainibe, C. Adami (LAM), D. Turpin, D. Götz (CEA/Irfu), H. Yang (IRAP), in which at 2025-10-13T17:39:42 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251013C (SVOM burst-id sb25101311) also detected by Fermi/GBM, I pointed at the coordinates RA(J2000)=23h 03m 22s: Dec(J2000)=-00d 12' 37" and started my observations with telescope of Nastro Verde Observatory - Sorrento (Naples), Italy. Member of: AAVSO - American Association of Variable Star Observers. GRB/UAI Gamma Ray Burst Section of Unione Astrofili Italiani. The observations started at 20:04:39 UT of 2025/10/13, after about 3.30 hours after the GRB trigger, with clear sky, with principal telescope SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME, using the V and Rc photometric filters. I took 20 unfiltered images of 60 sec in each filter. The images were added in groups of five to obtain a higher S/N Start End 20:04:39 UT 20:56:46 UT All images, calibrated with masterdark and masterflat have been measured with Maxim DL software I have detected a bright source at the enhanced position reported by GCNs (Konno et al. (GCN circ. 42226), Perez-Garcia et al. (GCN circ. 42225), Martin-Carrillo et al. (GCN circ. 42227), Masi (GCN circ. 42228), Palmerio et al. (GCN circ. 42229), Moskvitin et al. (GCN circ. 42230), Gompertz et al. (GCN circ. 42231), Watson et al. (GCN circ. 42241), LÃ³pez-CÃ¡mara et al. (GCN circ. 42242), Zhang et al. (GCN circ. 42248), Brosio et al. (GCN circ. 42251), Quintana-Ansaldo et al. (GCN circ. 42254), and Maksut et al. (GCN circ. 42256), U. Quadri et al.(GCN 42262), C. Adami et al.(GCN 42266), I. Peretto et al.(GCN 42267) at following position RA (J2000.0) 23 03 20.55 Dec (J2000.0) -00 12 37.0 with the following photometry: (JD) Mag Err Filter 2460962.3649074 17.259 0.101 V 2460962.3561574 16.903 0.065 V 2460962.3473842 16.697 0.041 V 2460962.3374884 16.576 0.044 V 2460962.3639930 16.5 0.044 Rc 2460962.3552430 16.43 0.039 Rc 2460962.3464815 16.281 0.027 Rc 2460962.3365625 16.114 0.023 Rc Magnitudes were estimated with the pan-STARRS cat and are derived using Lupton (2005) equations. Not corrected for galactic dust extinction.. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42269. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40339] GRB 251012A: Glowbug gamma-ray detection of a likely short burst
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42268 SUBJECT: GRB 251012A: Glowbug gamma-ray detection of a likely short burst DATE: 25/10/14 20:31:56 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil> C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 251012A, which was also detected by Fermi/GBM (GCN 42207). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-10-12 14:46:26.104 with a duration of 0.16 s and a total significance of about 13.0 sigma. The light curve comprises a single peak. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS, and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42268. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40338] GRB 251013C: MarSEC, optical afterglow photometry
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42267 SUBJECT: GRB 251013C: MarSEC, optical afterglow photometry DATE: 25/10/14 19:43:03 GMT FROM: I. Peretto at MarSEC (Marana Space Explorer Center) <ricerca(a)marsec.org> Ivo Peretto (MarSEC, Marana Space Explorer Center, Marana Di Crespadoro, VI, Italy) Member of: UAI/SSV - Unione Astrofili Italiani/Sezione Stelle Variabili, GRB section. AAVSO (American Association Variable Stars Observers). 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) and Stefano Lora, Giovanni Furlato and Giuseppe Peretto (MarSEC, Marana Space Explorer Center, Marana di Crespadoro, VI, Italy) report: We imaged the field of GRB 251013C detected by SVOM (Rakotondrainibe et al., GCN 42222), with the robotic telescope of (IAU station 565) with the telescope 14” RC Officine Stellari of MarSEC (Marana Space Explorer Center) with CCD Moravian G2-1600-MKII. The observations with a series of 90 sec exposures, 2025-10-13T23:13:26.703'UT of midpoint of exposure, with a Ritchey-Chretien telescope D=360 mm f/8. The afterglow was clearly detected at the following position: RA(J2000) = 23h 03m 20,7s Dec(J2000) = -00d 13' 37" We report our photometry analysis: HJD Rc Mag Err ------------------------------------- 2460962.4676701734 16.813 0.08 Weather conditions were good, sqm medium 20,85 We co-added 14 exposures of 90 sec. each. Magnitudes were estimated with the pan-STARRS cat and are derived using Lupton (2005) equations and are not corrected for galactic dust extinction. Reference: https://www.marsec.org/ The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42267. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40337] GRB 251013C: OHP/T193 optical afterglow photometry and spectroscopy
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42266 SUBJECT: GRB 251013C: OHP/T193 optical afterglow photometry and spectroscopy DATE: 25/10/14 19:29:02 GMT FROM: Christophe Adami at LAM <christophe.adami(a)lam.fr> C. Adami (LAM/Pytheas/AMU), B. Schneider (LAM), E. Le Floc'h (CEA/Irfu), A. de Ugarte Postigo (LAM), S. Basa (Pytheas/OHP/LAM), F. Schüssler (CEA/Irfu), N.A. Rakotondrainibe (LAM), report on behalf of a larger collaboration: We observed the field of GRB 251013C detected by FERMI (Fermi GBM Team, GCN Circ. 42221) and SVOM/ECLAIRs (Rakotondrainibe et al., GCN Circ. 42222) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. We obtained one exposure of 3min in the r-band starting at 19:28:38 UT on 2025-10-13. The optical counterpart previously reported by different groups is well detected. Consistent with previously reported photometric measurements, the preliminary magnitude derived for that source is: r’ = 15.92 +/- 0.04 mag (AB) We also obtained a 10min spectrum roughly covering the 4800-8200A range, starting at 19:19:40 UT 2025-10-13. We detect a strong continuum but no prominent lines in our range, consistently with the redshift measured by Martin-Carrillo (GCN 42227). The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitudes are not corrected for Galactic extinction. We used the STDWeb/STDPipe tools (Karpov 2025). We acknowledge the excellent support from the Observatoire de Haute-Provence and in particular Jean Balcaen and the SOPHIE observers J.B. Salomon and J.L. Halbwachs View this GCN Circular online at https://gcn.nasa.gov/circulars/42266. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40336] GRB 251014B: Swift ToO observations
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42265 SUBJECT: GRB 251014B: Swift ToO observations DATE: 25/10/14 18:34:34 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a ToO observation of the Fermi/GBM-detected event GRB 251014B. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021863 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the Fermi/GBM event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42265. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40335] GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42264 SUBJECT: GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization DATE: 25/10/14 17:20:18 GMT FROM: Ruslan Konno at Weizmann Institute of Science <ruslankonno(a)gmail.com> R. Konno (WIS), S. Garrappa (WIS), E. A. Zimmerman (WIS), A. Horowicz (WIS), E. O. Ofek (WIS), S. Ben-Ami (WIS), D. Polishook (WIS), O. Yaron (WIS), S. Fainer (WIS), A. Krassilchtchikov (WIS), Y. M. Shani (WIS), E. Segre (WIS), A. Gal-Yam (WIS), and S. Spitzer (WIS) report on behalf of the LAST Collaboration. We report observations of GRB 251013D, detected by Fermi (Fermi GBM Team, GCN 42224). Observations were conducted with the Large Array Survey Telescope (LAST; Ofek et al. 2023, PASP 135, 5001; Ben-Ami et al. 2023, PASP 135, 5002). We observed the field of GRB 251013D using 20 divergent telescopes (each with a 7.4 deg^2 FoV) in clear band (similar to the Gaia Bp band) over several epochs. Each coadd consists of 20x20 s exposures, yielding a limiting magnitude of about 20.5 AB mag. Our observations cover about 80% of the localization region within the HEALPix FITS file glg_healpix_all_bn251013762.fit (Fermi GBM Team, GCN 42224) and include the Swift/BAT-GUANO localization (DeLaunay et al., GCN 42244). We coadded the Swift/BAT-GUANO coverage obtained between 2025-10-13 22:22:33 UTC (T − T0 = 4.09 h) and 2025-10-14 01:02:54 UTC (T − T0 = 6.77 h) for a total integration of 120 x 20 s and performed image subtraction using reference images of this field. No new source was detected within the Swift/BAT-GUANO region down to a limiting magnitude of 21.14 (AB). No source brighter than 19.44 mag (AB) with significant variability (> 0.5 mag) was observed between the start and end of the observations of the same field. LAST is a survey telescope array of the Weizmann Astrophysical Observatory (https://www.weizmann.ac.il/wao/). View this GCN Circular online at https://gcn.nasa.gov/circulars/42264. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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