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

[vsnet-grb-info 40374] GRB 251013D: Swift/UVOT Observations
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42299 SUBJECT: GRB 251013D: Swift/UVOT Observations DATE: 25/10/15 20:20:03 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 251013D 71 ks after the Fermi/GBM trigger (GCN Circ. 42224; DeLaunay et al., GCN Circ. 42244). We detect an uncatalogued optical source near the position of XRT source #2 (Burrows et al., GCN Circ. 42291). There is no evidence of fading in the UVOT data thus far. The preliminary UVOT position is: RA (J2000) = 03:07:52.73 = 46.96971 (deg.) Dec (J2000) = +08:48:57.4 = 8.81595 (deg.) with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 71081 72734 1622 20.98+/-0.16 white 76655 78444 1758 20.78+/-0.13 white 82245 83695 1423 20.68+/-0.13 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.312 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/42299. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40373] GRB 251013C: Swift ToO observations
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42281 SUBJECT: GRB 251013C: Swift ToO observations DATE: 25/10/15 05:41:19 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: EDIT: This circular was submitted as the result of a system error regarding the follow up ToO observation for this GRB. The correct URL for GRB 251013C products is https://www.swift.ac.uk/xrt_products/01404126 This circular is, nonetheless, an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42281. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40372] GRB 251013D: Fermi GBM Observation
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42280 SUBJECT: GRB 251013D: Fermi GBM Observation DATE: 25/10/15 05:08:37 GMT FROM: Eva MP <eva.palafox(a)gmail.com> E. Palafox (INAOE) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 18:17:00.39 UT on 13 October 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251013D (trigger 782072225/251013762). which was also detected by Swift BAT (J. DeLaunay et al. 2025, GCN 42244). The Fermi GBM on-ground location is consistent with the Swift BAT position. The angle from the Fermi LAT boresight is 70 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 42 s (50-300 keV). The time-averaged spectrum from T0-2.0 to T0+53.2 s is best fit by a Comptonized function with Epeak = 129 +/- 12 keV, alpha = -0.9 +/- 0.1. A Band function fits equally well with Epeak = 103 +/- 16 and alpha = -0.8 +/- 0.2, and beta -2.3 +/- 0.2. The event fluence (10-1000 keV) in this time interval is (4.4 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+4.9 s in the 10-1000 keV band is 0.83 +/- 0.03 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/42280. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40371] GRB 251013C: Swift/UVOT Detection
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42298 SUBJECT: GRB 251013C: Swift/UVOT Detection DATE: 25/10/15 19:54:12 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 251013C 0.4 ks after the Fermi/SVOM trigger (GCN Circ. 42221, Rakotondrainibe et al., GCN Circ. 42222). A bright source consistent with the XRT position (Evans et al., GCN Circ. 42232) and optical counterpart (Palmerio et al., GCN Circ. 42223, Perez-Garcia et al., GCN Circ. 42225; Konno et al., GCN Circ. 42226; Masi et al., GCN Circ. 42228; Moskvitin, GCN Circ. 42230; Gompertz et al., GCN Circ. 42231; Garnavich, GCN Circ. 42240; Watson et al., GCN Circ. 42241) is detected in the UVOT exposures. The preliminary UVOT position is: RA (J2000) = 23:03:20.55 = 345.83562 (deg.) Dec (J2000) = -00:12:36.9 = -0.21024 (deg.) with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag u 480 5581 1785 15.22+/-0.03 white 129831 141519 2753 21.66+/-0.20 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.045 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/42298. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40370] Konus-Wind detection of GRB 251007A
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42297 SUBJECT: Konus-Wind detection of GRB 251007A DATE: 25/10/15 17:55:01 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru> A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long-duration GRB 251007A (Swift-BAT detection: Ambrosi et al., GCN 42146; Laha et al., GCN 42186; Glowbug detection: Cheung et al., GCN 42151; CALET-GBM detection: Yoshida et al., GCN 42156; AstroSat CZTI detection: Salunke et al., GCN 42167; Insight-HXMT detection: Wang et al., GCN 42183; SVOM/GRM detection: Yu et al., GCN 42184) triggered Konus-Wind at T0=70671.956 s UT (19:37:51.956). The burst light curve shows a multipeaked structure which starts at ~T0-44.6 s and has a total duration of ~66.4 s. The emission is seen up to ~4 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB251007_T70671/ As observed by Konus-Wind, the burst had a fluence of 3.89(-0.15,+0.16)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+0.656 s, of 7.08(-0.94,+0.95)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+24.832 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.09(-0.06,+0.06) and Ep = 395(-27,+31) keV (chi2 = 108/98 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.6 (chi2 = 108/97 dof). The spectrum near the maximum count rate (measured from T0+0.256 to T0+8.448 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model with alpha = -1.20(-0.07,+0.07) and Ep = 436(-41,+50) keV (chi2 = 98/81 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.4 (chi2 = 96/80 dof). All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/42297. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40369] Fermi Gamma-ray Burst Monitor trigger 782237334/251015673 is not a GRB
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42296 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 782237334/251015673 is not a GRB DATE: 25/10/15 17:53:14 GMT FROM: Suman Bala at USRA <sumanbala2210(a)gmail.com> S. Bala (USRA) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 782237334/251015673 at 16:08:49.43 UT on 15 October 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to distant particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/42296. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40368] GRB 251013C, GCN Circular 42267, errata corrige
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42295 SUBJECT: GRB 251013C, GCN Circular 42267, errata corrige DATE: 25/10/15 17:50:14 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). We report our photometry analysis: HJD Rc Mag Err ------------------------------------- 2460962.4676701734 17.581 0.09 Reference: https://www.marsec.org/ The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42295. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40367] GRB 251013C: detection of a radio counterpart at 15.5GHz
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42294 SUBJECT: GRB 251013C: detection of a radio counterpart at 15.5GHz DATE: 25/10/15 16:27:02 GMT FROM: Lauren Rhodes at McGill <lauren.rhodes(a)mcgill.ca> Lauren Rhodes (McGill/TSI), Andrew Hughes (Oxford), Rob Fender (Oxford), Dave Green (Cambridge), Dave Titterington (Cambridge) report: We observed the field of the afterglow candidate GRB 251013C (GCN 42221) with the Arcminute Microkelvin Imager Large-Array (AMI-LA) at 15.5 GHz beginning at UT 19:27:08.0 on 14-Oct-2025 for a total of 4 hours. The flux standard 3c286 was used to calibrate the bandpass response and flux scale of the AMI-LA and J2320+0513 was used as an interleaved complex gain calibrator. We detected a point source with a peak flux density of 0.34 +/- 0.08 mJy/beam with a position of RA = 23h03m20.5+/- 0.2s Dec = -00d12'26+/- 9" Further observations are planned. We thank the staff at the Mullard Radio Astronomy Observatory for carrying out these observations and operating the AMI-LA. View this GCN Circular online at https://gcn.nasa.gov/circulars/42294. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40366] GRB 251015A: Fermi GBM Final Real-time Localization
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42293 SUBJECT: GRB 251015A: Fermi GBM Final Real-time Localization DATE: 25/10/15 16:19:34 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 16:08:49 UT on 15 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251015A (trigger 782237334.425736 / 251015673). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 355.1, Dec = -56.1 (J2000 degrees, equivalent to J2000 23h 40m, -56d 06'), with a statistical uncertainty of 1.0 degrees. The angle from the Fermi LAT boresight is 167.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251015673/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251015673/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251015673/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42293. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40365] GRB 251013C: SVOM/ECLAIRs refined analysis
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42292 SUBJECT: GRB 251013C: SVOM/ECLAIRs refined analysis DATE: 25/10/15 15:52:54 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> H. Yang, M. Brunet, O. Godet (IRAP), B. Hubert (CEA), F. Piron (LUPM), N. A. Rakotondrainibe, C. Adami (LAM) Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of GRB 251013C (SVOM burst-id sb2525101311, GCN 42222) detected at T0 = 2025-10-13T17:39:42, which was also detected by SVOM/GRM and Fermi/GBM (GCN 42221). The burst that triggered ECLAIRs consists of a single peak, with a typical fast-rising and exponential-decay profile, starting at T0-0.4 s and lasting about 30 s in the 4-120 keV energy band. The time-averaged spectrum from the peak (T0-0.4 s to T0+30 s) in the 4-120 keV energy range is well fitted by a power-law model with a photon index of 1.59 +/-0.03. With this model, the total 4-120 keV fluence is (1.95 + 0.02/-0.03)e-06 erg/cm^2 . All the quoted errors are at the 68% confidence level. 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. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs point of contact for this burst is: Hui Yang (IRAP) (hui.yang(a)irap.omp.eu) View this GCN Circular online at https://gcn.nasa.gov/circulars/42292. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0