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

[vsnet-grb-info 40975] GRB 251130B: Fermi GBM Final Real-time Localization
by GCN Circulars 30 Nov '25

30 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42905 SUBJECT: GRB 251130B: Fermi GBM Final Real-time Localization DATE: 25/11/30 15:43:48 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 15:33:18 UT on 30 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251130B (trigger 786209603.108754 / 251130648). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 102.1, Dec = -45.5 (J2000 degrees, equivalent to J2000 06h 48m, -45d 30'), with a statistical uncertainty of 11.5 degrees. The angle from the Fermi LAT boresight is 108.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251130648/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251130648/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251130648/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42905. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40974] EP251030a: COLIBRÍ optical counterpart candidate
by GCN Circulars 30 Nov '25

30 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42904 SUBJECT: EP251030a: COLIBRÍ optical counterpart candidate DATE: 25/11/30 15:18:49 GMT FROM: Damien Dornic <ddornic(a)km3net.de> Damien Dornic (CPPM), Margarita Pereyra (UNAM), Stéphane Basa (UAR Pytheas), Rosa L. Becerra (UNAM), Alan M. Watson (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Nathaniel R. Butler (ASU), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), William H. Lee (UNAM), Kin Ramandeep Gill (UNAM), Noémie Globus (UNAM), Ocelotl López (UNAM), Diego López-Cámara (UNAM), Nikos Mandarakas (LAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We imaged the field of the EP251030a (Wu et al., GCN 42903) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2025-11-30T12:09:17 to 12:28 UTC (from 1.02 to 1.34 hours after the trigger) and obtained 16 minutes of simultaneous exposure in the r and z filters. The data were reduced, coadded and analysed with the COLIBRÍ pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. In the stacked image, we detect an uncatalogued source at the coordinates: RA = 101.0205 deg, Dec = 27.3840 deg with an uncertainty of 0.5 arcsec, compatible with the EP/FXT position (Wu et al., GCN 42903), at preliminary magnitudes of: r = 20.69 +/- 0.03 z = 19.45 +/- 0.03 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/42904. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40973] EP251130a: Einstein Probe detection of an X-ray transient
by GCN Circulars 30 Nov '25

30 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42903 SUBJECT: EP251130a: Einstein Probe detection of an X-ray transient DATE: 25/11/30 11:51:35 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> T. Wu, H. C. Ding (AHNU), Y. H. Jiang, Y. Wu (NJU), Y. Wang (PMO), W. J. Zhang, Y. Liu (NAO, CAS), on behalf of the Einstein Probe (EP) team: We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP251130a. The transient triggered EP-WXT (ID: 01709249022) at 2025-11-30T11:07:49 (UTC). The WXT position of the source is R.A. = 101.041 deg, DEC = 27.394 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically. Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 101.0242 deg, DEC = 27.3824 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). Further information will be updated when the telemetry data is received. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/42903. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40972] EP251129a/GRB 251129A: EP-FXT follow-up observations
by GCN Circulars 29 Nov '25

29 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42902 SUBJECT: EP251129a/GRB 251129A: EP-FXT follow-up observations DATE: 25/11/30 06:51:00 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. H. Jiang, Y. Wu, C. Y. Dai (NJU), Y. Wang (PMO), H. C. Ding, T. Wu (AHNU), W. J. Zhang, Y. Liu (NAO, CAS), on behalf of the Einstein Probe (EP) team: A follow-up observation of EP251129a / GRB 251129A (Wu et al., GCN 42884, Tan et al., GCN 42877) with the Follow-up X-ray Telescope (FXT) was performed automatically at 2025-11-29T03:16:08 (UTC), i.e. T0+2643 s, where T0 is reported by SVOM (Tan et al., GCN 42877) , with an exposure time of 5,003 s. The average FXT 0.5-10 keV spectrum of the observation can be fitted with an absorbed power law, with a fixed Galactic hydrogen column density of 2.94 x 10^20 cm^-2, an intrinsic hydrogen column density of 1.40 (-0.05/+0.05) x 10^22 cm^-2, and a photon index of 1.98 (-0.02/+0.02) . The derived average unabsorbed 0.5-10 keV flux is 1.74 (-0.02/+0.02) x 10^(-9) erg/s/cm^2. We performed two target-of-opportunity (ToO) follow-up observations with FXT at 2025-11-29T05:26:09 (UTC, T0+10,444 s) and 2025-11-29T12:34:30 (UTC, T0+36,145 s), with an exposure time of 2,786 s and 3,091 s, respectively. The average FXT 0.5-10 keV spectrum of the first ToO observation can be fitted with an absorbed power law, with a fixed Galactic hydrogen column density of 2.94 x 10^20 cm^-2, an intrinsic hydrogen column density of 1.04 (-0.11/+0.11) x 10^22 cm^-2, and a photon index of 2.45 (-0.05/+0.05) . The derived average unabsorbed 0.5-10 keV flux is 1.56 (-0.04/+0.04) x 10^(-10) erg/s/cm^2. The average FXT 0.5-10 keV spectrum of the second ToO observation can be fitted with an absorbed power law, with a fixed Galactic hydrogen column density of 2.94 x 10^20 cm^-2, an intrinsic hydrogen column density of 1.49 (-0.46/+0.46) x 10^22 cm^-2, and a photon index of 3.49 (-0.23/+0.23). The derived average unabsorbed 0.5-10 keV flux is 9.20 (-0.75/+0.82) x 10^(-13) erg/s/cm^2. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/42902. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40971] GRB 251130A: Fermi GBM Final Real-time Localization
by GCN Circulars 29 Nov '25

29 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42901 SUBJECT: GRB 251130A: Fermi GBM Final Real-time Localization DATE: 25/11/30 00:53:39 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 00:43:07 UT on 30 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251130A (trigger 786156192.430142 / 251130030). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 176.6, Dec = -60.4 (J2000 degrees, equivalent to J2000 11h 46m, -60d 23'), with a statistical uncertainty of 5.1 degrees. The angle from the Fermi LAT boresight is 99.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251130030/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251130030/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251130030/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42901. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40970] GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
by GCN Circulars 29 Nov '25

29 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42900 SUBJECT: GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460 DATE: 25/11/29 20:56:25 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct(a)iaa.es> R. Sanchez-Ramirez, A. J. Castro-Tirado, S. Guziy, M.D. Caballero-Garcia, I. Perez-Garcia, E. Fernandez-Garcia and S. Wu (IAA-CSIC), A.M. Garcia Rodriguez (IAC), D. Gonzalez (GTC), C. Hernandez (GTC), M. Gritsevich (Univ. of Helsinki), Y.-D. Hu (GXI) and L. Piro (INAF), on behalf of a larger collaboration, report: Following the detection of GRB 251129A by SVOM/ECLAIRs (Tan et al., GCN 42877, GCN 42879), Einstein Probe (EP Team et al., GCN 42884), and by additional Swift ToO observations (Evans, GCN 42888), we observed the optical afterglow detected by Angulo et al. (GCN 42880) and further reported (Watson, GCN 42883, Wu et al., GCN 42882, Masi, GCN 42885, Li et al., GCN 42887, Lipunov et al. GCN 42892, Moskvitin et al., GCN 42897 and Guziy et al., GCN 42899), with the 10.4m GTC telescope, at the Spanish Roque de los Muchachos Observatory, on the island of La Palma, equipped with the OSIRIS+ instrument. The spectroscopic data consisted of 900s exposures using grisms R1000B and R2500I, covering the spectral range between 3,600 and 10,000 A. The observations started on Nov 29, 05:32 UT (i.e. 3.01 h after the burst trigger), and were carried out at high airmass (X~2). From a preliminary reduction, we find a highly absorbed continuum, showing several metal absorption with complex velocity structure. We interpret these lines as coming from CrII, FeII, FeII*, MgII, NiII, SiII, ZnII, all at z=1.460. The detection of iron fine structure lines links this system to the GRB. View this GCN Circular online at https://gcn.nasa.gov/circulars/42900. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40969] GRB 251129A / EP251129a: OSN and CAHA optical follow-up
by GCN Circulars 29 Nov '25

29 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42899 SUBJECT: GRB 251129A / EP251129a: OSN and CAHA optical follow-up DATE: 25/11/29 20:25:20 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct(a)iaa.es> S. Guziy, A. Sota, M.D. Caballero-Garcia, R. Sanchez-Ramirez, I. Olivares, I. Perez-Garcia, E. Fernandez-Garcia, S. Wu and A.J. Castro-Tirado (IAA-CSIC), J.I. Vico Linares, A. Fernandez-Martin and J. Flores-Martin (CAHA), E. Gomez, B. Rodriguez, J.P. Lopez, N. Morant Juan, I. Castillo, A. Lozano-Fernandez, F. Lopez-Martinez, M. Salah-Martinez and R. Ardon-Leon (VIU, Valencia), M. Gritsevich (Univ. of Helsinki) and Y.-D. Hu (GXI), on behalf of a larger collaboration, report: Following the detection of GRB 251129A/EP251129a by SVOM (Tan et al. GCNC 42879) and EP (Wu et al. GCNC 42884) we imaged the gamma-ray burst error box with both the 0.9 and 1.5m telescopes at Sierra Nevada Observatory. In addition to them, we also used the 1.23m and 2.2m telescopes at the nearby Calar Alto Observatory. We clearly detect the optical afterglow discovered by Angulo et al. (GCNC 42880), also reported by Wu et al. (GCNC 42882), Masi (GCNC 42885), Li et al. (GCNC 42887), Lipunov et al. (GCNC 42892) and Moskvitin et al. (GCNC 42897). At both Sierra Nevada and Calar Alto observatories we measure R = 19.8 +/- 0.2 and i = 19.9 +/- 0.3 respectively (2.47 h and 2.90 h after the burst onset time). This preliminary photometry is based on nearby stars from the USNO-B1 catalogue (R2 magnitudes) and SDSS and is not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/42899. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40968] GRB 251128A: AstroSat CZTI detection
by GCN Circulars 29 Nov '25

29 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42898 SUBJECT: GRB 251128A: AstroSat CZTI detection DATE: 25/11/29 18:47:43 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> M. Tembhurnikar (IUCAA), A. Arya (IITB), A. Goyal (IITB), S. Salunke (IUCAA), Harsha K. H. (IUCAA), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a short GRB 251128A which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 42865), Swift BAT-GUANO (DeLaunay et. al., GCN Circ. 42874), and Insight-HXMT/HE (Zhang et. al., GCN Circ. 42893). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2025-11-28 04:23:02 UTC. The measured peak count rate associated with the burst is 154 (+2, -2) counts/s above the background in the combined data of two quadrants (out of four), with a total of 2558 (+298, -336) counts. The local mean background count rate was 260 (+2, -2) counts/s. Using cumulative rates, we measure a T90 of 45.3 (+2.8, -2.2) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2025-11-28 04:23:52 UTC. The measured peak count rate associated with the burst is 509 (+72, -62) counts/s above the background in the combined data of all quadrants, with a total of 5062 (+723, -752) counts. The local mean background count rate was 1445 (+6, -5) counts/s. We measure a T90 of 47.1 (+1.9, -2.7) s from the cumulative Veto light curve. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/42898. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40967] GRB 251129A / EP251129a: SAO RAS optical observations
by GCN Circulars 29 Nov '25

29 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42897 SUBJECT: GRB 251129A / EP251129a: SAO RAS optical observations DATE: 25/11/29 17:59:49 GMT FROM: Alexander Moskvitin at SAO RAS <mosk(a)sao.ru> A. S. Moskvitin and O. I. Spiridonova (SAO RAS) report on behalf of GRB follow-up team. We observed the field of the SVOM GRB 251129A (Tan et al., GCN 42877) also detected by Einstein Probe as EP251129a (Wu et al., GCN 42884) and Swift (Evans, GCN 42888; Page et al., GCN 42891) with the Zeiss-1000 1m telescope of the SAO RAS on November 29, 15:27:01--16:00:22 UT (t_mid - T0 = 0.54973 days). We obtained 6 * 300 sec images in Rc band. The optical afterglow (Angulo et al., GCN 42880; Wu et al., GCN 42882; Watson, GCN 42883; Masi, GCN 42885; Li et al., GCN 42887; Lipunov et al., GCN 42892) is clearly detected in the stacked frame with the following brightness. Date UT start t-T0 Exp. Filter OT Err. UL (mid,days) (n*s) (3sigma) 2025-11-29 15:27:01 0.54973 6*300 Rc 21.00 0.07 22.8 This preliminary photometry is based on nearby stars from the USNO-B1 catalogue (R2 magnitudes) and is not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/42897. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40966] GRB 251126A: SAO RAS optical observations
by GCN Circulars 29 Nov '25

29 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42896 SUBJECT: GRB 251126A: SAO RAS optical observations DATE: 25/11/29 17:15:20 GMT FROM: Alexander Moskvitin at SAO RAS <mosk(a)sao.ru> V. Goranskij (SAI MSU, SAO RAS), A. Moskvitin (SAO RAS), V. Shergin (SAO RAS), A. Volnova (IKI), N. Pankov (HSE, IKI), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN and GRB follow-up team. We observed the field of the Swift GRB 251126A (Caputo et al., GCN 42843; Evans, GCN 42845; Goad et al., GCN 42851; Page et al., GCN 42860; Barthelmy et al., GCN 42876) with the Zeiss-1000 1m telescope of the SAO RAS on November 28/29 night. We obtained a series of 300 and 600 sec. images in Rc band under a good weather conditions and FWHM of about 1".8. The optical afterglow (Swain, GCN 42844; Fu et al., GCN 42848; Reguitti et al., GCN 42849; Broens et al., GCN 42850; Anguloet al., GCN 42855; Pulido-Torres et al; GCN 42856; Gupta et al., GCN 42857; Cotter et al., GCN 42858; Seki et al., GCN 42859; Volnova et al., GCN 42861; Breeveld and Caputo, GCN 42863; Gupta et al., GCN 42864; Burkhonov et al., GCN 42866; Maksut et al., GCN 42868; Moskvitin et al, GCN 42870; Adami et al., GCN 42871; Pankov et al., GCN 42875) is clearly detected in the stacked frame. We report preliminary brightness of the optical afterglow. Date UT start t-T0 Exp. Filter OT Err. UL (mid,days) (n*s) (3sigma) 2025-11-28 22:35:56 2.2236 8*300+4*600 Rc 23.15 0.18 23.7 The photometry is based on nearby stars from the USNO-B1 catalogue (R2 magnitudes)and is not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/42896. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0