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

[vsnet-grb-info 41097] GRB 251205A: Swift-XRT refined Analysis
by GCN Circulars 07 Dec '25

07 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43017 SUBJECT: GRB 251205A: Swift-XRT refined Analysis DATE: 25/12/07 03:50:01 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> S. Dichiara (PSU), J.A. Kennea (PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), C. Salvaggio (INAF-OAB), M. Ferro (INAF-OAB), R. Brivio (INAF-OAB) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 6.3 ks of XRT data for GRB 251205A, from 129 s to 94.1 ks after the trigger. The data comprise 352 s in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The late-time light curve (from T0+9.7 ks) can be modelled with a power-law decay with a decay index of alpha=0.77 (+0.12, -0.11). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.14 (+/-0.06). The best-fitting absorption column is 5.6 (+1.3, -1.2) x 10^20 cm^-2, in excess of the Galactic value of 1.2 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.95 (+0.16, -0.15) and a best-fitting absorption column of 3.8 (+3.5, -2.6) x 10^20 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.4 x 10^-11 (3.7 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.8 (+3.5, -2.6) x 10^20 cm^-2 Galactic foreground: 1.2 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.95 (+0.16, -0.15) The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/01420873. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43017. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41096] GRB 251205A: Swift/UVOT Detection
by GCN Circulars 06 Dec '25

06 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43016 SUBJECT: GRB 251205A: Swift/UVOT Detection DATE: 25/12/06 18:47:19 GMT FROM: N. Klingler at NASA-GSFC/UMBC/CRESST II <noelklingler(a)gmail.com> N. Klingler (NASA-GSFC / UMBC / CRESST II) and Sophia Lanava (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 251205A 149 s after the BAT trigger (Lanava et al., GCN Circ. 43005). A source consistent with the XRT position (RA, Dec = 13h 21m 05.26s, +29d 55' 44.2"; Beardmore et al., GCN Circ. 43007) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 13:21:05.34 = 200.27223 (deg.) Dec (J2000) = +29:55:44.0 = 29.92890 (deg.) with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence). Preliminary detections 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) Mag white 148.9 298.7 17.61 +/- 0.06 white 586.8 606.5 16.96 +/- 0.09 white 759.1 869.1 16.89 +/- 0.08 white 16513.5 17308.6 17.77 +/- 0.05 b 562.4 582.2 17.32 +/- 0.17 b 734.9 754.7 17.29 +/- 0.18 b 15601.3 16508.4 18.18 +/- 0.05 u 306.8 556.6 16.65 +/- 0.06 u 710.3 730.0 16.57 +/- 0.16 u 22323.1 22838.7 17.51 +/- 0.06 v 636.4 656.2 17.10 +/- 0.27 v 808.6 828.4 16.92 +/- 0.24 v 10660.9 11393.6 18.45 +/- 0.10 uvw1 685.8 705.5 16.18 +/- 0.18 uvw1 21416.9 22316.6 17.83 +/- 0.07 uvw2 9754.6 10654.4 18.44 +/- 0.10 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.014 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/43016. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41095] GRB 251205A: Liverpool Telescope optical follow-up observations
by GCN Circulars 06 Dec '25

06 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43015 SUBJECT: GRB 251205A: Liverpool Telescope optical follow-up observations DATE: 25/12/06 18:26:59 GMT FROM: A. Bochenek at Liverpool John Moores University <a.m.bochenek(a)2023.ljmu.ac.uk> A. Bochenek, D. A. Perley (LJMU), report: We observed the field of GRB 251205A (Lanava et al., GCN 43005) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 4x100s exposures the SDSS i and r filters starting at 2025-12-06 05:37:14 UT, approximately 5.95 hours after trigger. Some exposures were affected by telescope movement and had to be discarded. We report detections in both filters, at the position first reported by Lanava et al. GCN 43005: MJD (mid) T_mid-T_0 Filter Mag. (AB) 61015.23465 5.97 h i 17.93 ± 0.05 61015.24283 6.16 h r 18.06 ± 0.03 The photometry is consistent with measurements by Lanava et al. GCN43005; Lipunov et al. GCN 43006; de Ugarte Postigo et al. GCN 43008; Malesani et al. GCN 43009; O’Neill et al., GCN 43010; Mandarakas et al. GCN 43011 and Pankov et al., GCN 43012. The photometry was obtained using nearby PanSTARRS secondary standards and was not corrected for extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43015. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41094] GRB 251203C: Swift/UVOT Upper Limit
by GCN Circulars 06 Dec '25

06 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43014 SUBJECT: GRB 251203C: Swift/UVOT Upper Limit DATE: 25/12/06 18:22:42 GMT FROM: N. Klingler at NASA-GSFC/UMBC/CRESST II <noelklingler(a)gmail.com> Swift/UVOT has performed follow-up observations of the field of GRB 251203C, starting 20.3 ks after the SVOM trigger sb25120305 (Brunet et al; GCN Circ. 42976). No source is detected at the position of the optical counterpart (R.A., Dec. = 51.701538, -7.382688) reported by Li et al. (GCN Circ. 42987) and Turpin et al. (GCN Circ. 42988). 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) are: Filter T_start(s) T_stop(s) Exp(s) Mag(AB) u 20269 20514 241 >20.69 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.046 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/43014. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41093] Konus-Wind detection of GRB 251118A
by GCN Circulars 06 Dec '25

06 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43013 SUBJECT: Konus-Wind detection of GRB 251118A DATE: 25/12/06 16:38:47 GMT FROM: Valentina Panteleeva at Ioffe Institute <panteleevav228(a)gmail.com> V. Panteleeva, D. Frederiks, A. Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long-duration GRB 251118A (Fermi-GBM detection: The Fermi GBM team, GCN 42743; Palafox and Meegan, GCN 42783; BALROG localization: Preis and Greiner, GCN 42745; Fermi-LAT detection: Gupta and Khalil, GCN 42752; GECAM-B detection: Ren et al., GCN 42779; Glowbug detection: Cheung et al., GCN 42784) triggered Konus-Wind at T0=73904.449 s UT (20:31:44.449). The burst light curve starts, at ~T0-20.5 s, with a short soft initial pulse (precursor) which had a duration of about 25.8 s. The precursor is followed, starting at ~T0+32 s, by the main episode, lasting for ~25 s. The total duration of the burst is ~48 s. The emission in the main episode is seen up to ~3 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB251118_T73904/ As observed by Konus-Wind, the burst had the total fluence of 1.07(-0.03,+0.03)x10^-4 erg/cm2, and the 64-ms peak flux, measured from T0+35.776 s, of 2.03(-0.15,+0.15)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the initial pulse (measured from T0 to T0+8.448 s) is best described 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 = -1.94(-0.03,+0.12) and Ep < 41 keV (chi2 = 89/85 dof). Fitting this spectrum by a GRB (Band) model results in the same estimates of alpha and Ep, and gives only an upper limit on the high energy photon index beta of -2.8 (chi2 = 89/84 dof). The time-averaged spectrum of the main episode (measured from T0+33.024 to T0+65.536 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.29(-0.03,+0.04), the high energy photon index beta = -2.56(-0.08,+0.07), the peak energy Ep = 154(-5,+5) keV (chi2 = 110/97 dof). The spectrum near the maximum count rate (measured from T0+33.024 to T0+36.608 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.74(-0.05,+0.06), the high energy photon index beta = -2.53(-0.10,+0.08), the peak energy Ep = 251(-12,+12) keV (chi2 = 68/69 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/43013. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41092] GRB 251205A: Zeiss-1000 Koshka observatory optical observations
by GCN Circulars 06 Dec '25

06 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43012 SUBJECT: GRB 251205A: Zeiss-1000 Koshka observatory optical observations DATE: 25/12/06 14:44:43 GMT FROM: Alexei Pozanenko at IKI, Moscow <grb.alex(a)gmail.com> N. Pankov (HSE,IKI), A. Novichonok (Petrozavodsk State University, KIAM), S. Schmalz (KIAM), A. Volnova (IKI), A. Pozanenko (IKI) report on behalf of IKI GRB-FuN: We observed the optical afterglow of GRB 251205A (Lanava et al., GCN 43005; Lipunov et al., GCN 43006; de Ugarte Postigo et al., GCN 43008; Malesani et al., GCN 43009; O'Neill et al., GCN 43010) using the Zeiss-1000 telescope at Koshka observatory (INASAN). The observations started/ended on 2025-12-06 (UT) 00:57:28/04:07:07. Preliminary photometry of the initial stacked image is the following Date UT start t-T0 Exp. Filter OT Err. UL(3sigma) (mid, days) (s) 2025-12-06 00:57:28 0.05747 10*90 R 17.92 0.06 20.5 The photometry is based on nearby USNO-B1.0 stars and not corrected for Galaxy extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43012. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41091] GRB 251205A: Zeiss-1000 Koshka observatory optical observations
by GCN Circulars 06 Dec '25

06 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43012 SUBJECT: GRB 251205A: Zeiss-1000 Koshka observatory optical observations DATE: 25/12/06 14:44:43 GMT FROM: Alexei Pozanenko at IKI, Moscow <grb.alex(a)gmail.com> N. Pankov (HSE,IKI), A. Novichonok (Petrozavodsk State University, KIAM), S. Schmalz (KIAM), A. Volnova (IKI), A. Pozanenko (IKI) report on behalf of IKI GRB-FuN: We observed the optical afterglow of GRB 251205A (Lanava et al., GCN 43005; Lipunov et al., GCN 43006; de Ugarte Postigo et al., GCN 43008; Malesani et al., GCN 43009; O'Neill et al., GCN 43010) using the Zeiss-1000 telescope at Koshka observatory (INASAN). The observations started/ended on 2025-12-06 (UT) 00:57:28/04:07:07. Preliminary photometry of the initial stacked image is the following Date UT start t-T0 Exp. Filter OT Err. UL(3sigma) (mid, days) (s) 2025-12-06 00:57:28 0.05747 10*90 R 17.92 0.06 20.5 The photometry is based on nearby USNO-B1.0 stars and not corrected for Galaxy extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43012. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41090] GRB 251205A: Zeiss-1000 Koshka observatory optical observations
by GCN Circulars 06 Dec '25

06 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43012 SUBJECT: GRB 251205A: Zeiss-1000 Koshka observatory optical observations DATE: 25/12/06 14:44:43 GMT FROM: Alexei Pozanenko at IKI, Moscow <grb.alex(a)gmail.com> N. Pankov (HSE,IKI), A. Novichonok (Petrozavodsk State University, KIAM), S. Schmalz (KIAM), A. Volnova (IKI), A. Pozanenko (IKI) report on behalf of IKI GRB-FuN: We observed the optical afterglow of GRB 251205A (Lanava et al., GCN 43005; Lipunov et al., GCN 43006; de Ugarte Postigo et al., GCN 43008; Malesani et al., GCN 43009; O'Neill et al., GCN 43010) using the Zeiss-1000 telescope at Koshka observatory (INASAN). The observations started/ended on 2025-12-06 (UT) 00:57:28/04:07:07. Preliminary photometry of the initial stacked image is the following Date UT start t-T0 Exp. Filter OT Err. UL(3sigma) (mid, days) (s) 2025-12-06 00:57:28 0.05747 10*90 R 17.92 0.06 20.5 The photometry is based on nearby USNO-B1.0 stars and not corrected for Galaxy extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43012. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41089] GRB 251205A: COLIBRÍ optical observations
by GCN Circulars 06 Dec '25

06 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43011 SUBJECT: GRB 251205A: COLIBRÍ optical observations DATE: 25/12/06 12:07:07 GMT FROM: nikos.mandarakas(a)lam.fr Nikos Mandarakas (LAM), Margarita Pereyra (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), 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 Swift GRB 251205A (S. Lanava et al., GCN Circ. 43005) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2025-12-06 10:04:31 to 10:47:46 UTC (from 10.41 to 11.13 hours after the trigger) and obtained 32 minutes of simultaneous exposure in the r and z filters. The data were reduced and coadded with the COLIBRÍ pipeline and analysed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. We detected the optical counterpart S. Lanava et al. (GCN Circ. 43005); V. M. Lipunov et al. (GCN Circ. 43006); A. de Ugarte Postigo et al. (GCN Circ. 43008); D. B. Malesani et al. (GCN Circ. 43009) and D. O’Neill et al. (GCN Circ. 43010), at a preliminary magnitude of: r = 18.26 +/- 0.03 z = 17.97 +/- 0.02 Further observations 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/43011. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41088] GRB 251205A: GOTO optical afterglow detection
by GCN Circulars 06 Dec '25

06 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43010 SUBJECT: GRB 251205A: GOTO optical afterglow detection DATE: 25/12/06 11:03:38 GMT FROM: d.s.oneill(a)bham.ac.uk D. O'Neill, G. Ramsay, A. Kumar, B. Gompertz, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, K. Ulaczyk, S. Belkin, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien,, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, D. Pollacco, J. Casares Vel'azquez, T. Killestein, B. Godson on behalf of GOTO collaboration: We report on optical observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al. 2024) in response to the GRB 251205A. Serendipitous observations from the all-sky survey covered the position of the counterpart (Malesani et al., GCN 43009; Lanava et al., GCN 43005; Lipunov et al., GCN 43006; de Ugarte Postigo et al., GCN 43008) at 2025-12-06 06:12:01 UT, (+6.5h post trigger). Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations. The counterpart was detected in the GOTO L-band (400-700nm) mag = 18.16 ± 0.12 (AB). Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and not corrected for Galactic extinction. GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester, the University of Birmingham and the Instituto de Astrofisica de Canarias (IAC). View this GCN Circular online at https://gcn.nasa.gov/circulars/43010. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

2025

2024

2023

2022

2021