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

[vsnet-grb-info 40360] GRB 251014B: VLT/FORS2 Optical Observation
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42287 SUBJECT: GRB 251014B: VLT/FORS2 Optical Observation DATE: 25/10/15 13:01:17 GMT FROM: Roberto Ricci at INAF-IRA <ricci(a)ira.inaf.it> Muskan Yadav (U Rome), Yu-Han Yang (U Rome), Roberto Ricci (U Rome), Niccolò Passaleva (U Rome), Rosa Becerra (U Rome), Eleonora Troja (U Rome), Lei Hu (Upenn) report on behalf of the ERC BHianca team: We observed the Swift-BAT/GUANO (Ronchini et al., GCN 42263) field of GRB 251014B detected by Fermi-GBM (trigger number 782110046) with the FORS2 imager on the ESO VLT UT1 (Antu). Observations started on Oct 15th, 2025 at 05:22 UT (24.6 hours after the trigger) and were carried out in the R filter with an average airmass of ~1.06 and exposure time of 20 minutes. Image subtraction against the SkyMapper Southern Survey (SMSS) Fourth Data Release (DR4) catalog (Onken et., 2024) shows no new uncataloged sources down to a 3-sigma limiting magnitude of ~24 AB mag. Several fainter sources are visible within the XRT localization of source #2 (Evans et al., GCN 42265) within the BAT localization, however they match catalogued counterparts in the Dark Energy Survey (DES) catalogue (DR2; Abbott et al. 2021) and, without a deeper template image, we cannot assess their variability. 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/42287. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40359] GRB 251014D: Swift/UVOT Upper Limits
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42286 SUBJECT: GRB 251014D: Swift/UVOT Upper Limits DATE: 25/10/15 12:45:11 GMT FROM: Alice Breeveld at MSSL-UCL <a.breeveld(a)ucl.ac.uk> A.A. Breeveld (UCL-MSSL) and N. J. Klingler (GSFC/UMBC/CRESSTII) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 251014D 160 s after the BAT trigger (Klingler et al., GCN Circ. 42274). No optical afterglow consistent with the XRT position (Page et al., GCN Circ. 42284)is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 160 310 147 >20.7 white 160 4287 344 >20.9 v 4498 4697 197 >19.2 b 3882 5439 317 >19.9 u 318 5312 204 >19.8 w1 4907 5107 197 >19.7 m2 4702 4902 197 >19.6 w2 4293 4493 197 >19.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.020 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/42286. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40358] GRB 251014D: BOOTES-6/DPRT optical upper limit
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42285 SUBJECT: GRB 251014D: BOOTES-6/DPRT optical upper limit DATE: 25/10/15 11:12:43 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct(a)iaa.es> S. Guziy, I. Perez-Garcia, E. Fernandez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S.-Y. Wu and A. J. Castro-Tirado (IAA-CSIC, Granada), P. J. Meintjes and H. J. van Heerden (UFS, South Africa), A. Martin-Carrillo and L. Hanlon (UCD, Ireland), M. Gritsevich (Univ. of Helsinki), M. Jelinek (ASU-CAS), A. Kumar (ARIES) and C. J. Perez del Pulgar (UMA, Malaga), on behalf of a larger collaboration, report: Following the detection of GRB 251014D by Swift/BAT (Klingler et al., GCNC 42272), the BOOTES-6/DPRT 0.6m robotic telescope at Boyden Observatory in Maselspoort (South Africa) responded to this event starting on Oct 14, 23:03 UT (~ 1.1 h after trigger) with 120s clear-filter images. No new source is detected within the Swift/XRT X-ray afterglow error box (Page et al., GCNC 42284) up to magnitude 18.3 using Gaia DR3 Gmag magnitude as reference. Further images were gathered, resulting on an upper limit of 21.0 (a coadd of 1200s on the aggregate, 1.6 post burst, at 23:30 UT). We thank the staff at Boyden Observatory for their excellent support. View this GCN Circular online at https://gcn.nasa.gov/circulars/42285. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40357] GRB 251014D: Swift-XRT afterglow detection
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42284 SUBJECT: GRB 251014D: Swift-XRT afterglow detection DATE: 25/10/15 10:20:16 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), S. Campana (INAF-OAB), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), S. Dichiara (PSU), J.A. Kennea (PSU), D.N. Burrows (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of GRB 251014D. We searched for X-ray sources in 2.9 ks of Photon Counting (PC) mode data. The total exposure at the position of the afterglow (see below) is 5.0 ks, obtained between T0+159.4 s and T0+22.3 ks. An uncatalogued X-ray source is detected within the estimated 3-sigma Swift-BAT error region (296 arcsec) and is fading with >3-sigma significance, and is therefore likely the GRB afterglow. Using 1351 s of PC mode data and 3 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 323.92080, -41.85533 which is equivalent to: RA (J2000): 21h 35m 40.99s Dec(J2000): -41d 51' 19.2" with an uncertainty of 3.4 arcsec (radius, 90% confidence). The light curve can be modelled with a power-law decay with a decay index of alpha=1.71 (+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 1.64 (+/-0.06). The best-fitting absorption column is 9.7 (+1.9, -1.8) x 10^20 cm^-2, in excess of the Galactic value of 2.1 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.1 x 10^-11 (4.6 x 10^-11) erg cm^-2 count^-1. A summary of the WT-mode spectrum is thus: Total column: 9.7 (+1.9, -1.8) x 10^20 cm^-2 Galactic foreground: 2.1 x 10^20 cm^-2 Excess significance: 6.8 sigma Photon index: 1.64 (+/-0.06) The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/01404126. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/01404126. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42284. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40356] GRB 251013C: MAO/AZT-22 optical observations
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42283 SUBJECT: GRB 251013C: MAO/AZT-22 optical observations DATE: 25/10/15 09:38:38 GMT FROM: Yodgor Rajabov at UBAI <rajabov(a)astrin.uz> B.Abidkhanov, Y. Rajabov, O. Burkhonov, S. Ehgamberdiev, Y. Tillayev (UBAI), A. Shaymanov (Maidanak Observatory/UBAI) report on behalf of UBAI team. We observed the field of the GRB 251013C (Rakotondrainibe et al., GCN Circ. 42222) with the 1.5-m at Maidanak Observatory telescope AZT-22 equipped with the 4kx4k CCD SNUCAM camera (Im et al., 2010). The OT (Palmerio et al., GCN Circ. 42223; Perez-Garcia et al., GCN Circ. 42225; Konno et al., GCN Circ. 42226; Martin-Carrillo et al., GCN Circ. 42227; Masi et al., GCN Circ. 42228; Palmerio et al., GCN Circ. 42229; Moskvitin et al., GCN Circ. 42230; Gompertz et al., GCN Circ. 42231; Lipunov et al., GCN Circ. 42235; Garnavich et al., GCN Circ. 42240; Watson et al., GCN Circ. 42241; Lopez-Camara et al., GCN Circ. 42242; Zhang et al., GCN Circ. 42248; Brosio et al., GCN Circ. 42251; Reguitti et al., GCN Circ. 42253; Quintana-Ansaldo et al., Circ. GCN 42254; Maksut et al., GCN Circ. 42256; Ghosh et al., GCN Circ. 42261; Quadri et al., GCN Circ. 42262; Adami et al. GCN Circ. 42266; Peretto et al., GCN Circ. 42267; Ruocco et al., GCN Circ. 42269; Calapai, GCN Circ. 42275; Adami et al. GCN Circ. 42276; and Globus et all GCN 42279 ) is clearly detected in the individual and stacked frames. Preliminary photometry is as follows: Date UTstart Exptime t-T0 Filter OT Err. UL Site/Telescope (nxs) (mid, days) 2025-10-14 17:34:48 6x300 0.99659 R 20.96 0.04 23.10 MAO/AZT-22 All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained in Johnson Cousins filters were calibrated using the PanSTARRS DR1 catalog. The data has not corrected for the Galactic extinction. Maidanak astronomical observatory (MAO) is an observational facility of the Ulugh Beg Astronomical Institute (UBAI), Uzbekistan Academy of Sciences (http://maidanak.uz/) View this GCN Circular online at https://gcn.nasa.gov/circulars/42283. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40355] GRB 251011B: SVOM/VT optical upper limit
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42282 SUBJECT: GRB 251011B: SVOM/VT optical upper limit DATE: 25/10/15 07:42:44 GMT FROM: Yinuo Ma <mayn(a)bao.ac.cn> Y. N. Ma, H. L. Li, Z. H. Yao, L. P. Xin, Y. L. Qiu, C. Wu, 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, D. H. Zhao (NAOC), J. Palmerio (CEA), Y. H. Cheng (YNU), Y. Wang (PMO) report on behalf of the SVOM/VT team. SVOM performed a Target of Opportunity observation of GRB 251011B detected by Swift/BAT, Fermi/GBM, and SVOM/GRM (D'Ai et al., GCN 42197; Fermi GBM team, GCN 42196; Evans et al., GCN 42201; Mukherjee et al., GCN 42204; Sbarufatti et al., GCN 42205; Zao et al., GCN 42206). SVOM/VT began observing the field at 2025-10-11 09:06:00 UTC, 1.961 hours after T0, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. No uncatalogued sources, compared to Legacy Survey, were detected in our single or stacked images within the error box provided by Swift/XRT position (D'Ai et al., GCN 42197; Evans et al., GCN 42201), the three sigma limits are: mid-time | exposure time | band | upper limit (AB) ----------|-----------------|-------|----------------- 2.3 h | 44*50 sec | VT_B | > 23.2 mag 2.3 h | 41*50 sec | VT_R | > 23.3 mag Our results are consistent with MASTER (Balanutsa et al., GCN 42203) and Swift/UVOT (Siegel & D'Ai, GCN 42209). 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/42282. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40354] 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: Swift has initiated a ToO observation of the SVOM/ECLAIRs-detected event GRB 251013C. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021862 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 SVOM/ECLAIRs 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/42281. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40353] 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 T0-6.1 to T0+15.4 s is best fit by a Comptonized function with Epeak = 129 +/- 12 keV, alpha = -0.9 +/- 0.1. 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 40352] GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42279 SUBJECT: GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations DATE: 25/10/15 04:56:43 GMT FROM: globus(a)astro.unam.mx Noémie Globus (UNAM), Jean-Grégoire Ducoin (CPPM), Alan M. Watson (UNAM), Camila Angulo (UNAM), Ny Avo Rakotondrainibe (LAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Dalya Akl (NYUAD), Sarah Antier (OCA), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Leonardo García-García (UNAM), Ramandeep Gill (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), and Antonio de Ugarte Postigo (LAM) report: We imaged the field of the SVOM GRB 251013C (Rakotondrainibe et al., GCN Circ. 42222) using the DDRAGO two-channel, wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope from 2025-10-15 02:56 to 04:18 UTC (33.27 to 34.64 hours after the trigger), obtaining 32 minutes of exposure in the g filter, 32 minutes in the r filter, and 64 minutes in the z filter. The images were analyzed 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 (Palmerio et al., GCN Circ. 42223; Perez-Garcia et al., GCN Circ. 42225; Konno et al., GCN Circ. 42226; Martin-Carrillo et al., GCN Circ. 42227; Masi et al., GCN Circ. 42228; Palmerio et al., GCN Circ. 42229; Moskvitin et al., GCN Circ. 42230; Gompertz et al., GCN Circ. 42231; Lipunov et al., GCN Circ. 42235; Garnavich et al., GCN Circ. 42240; Watson et al., GCN Circ. 42241; Lopez-Camara et al., GCN Circ. 42242; Zhang et al., GCN Circ. 42248; Brosio et al., GCN Circ. 42251; Reguitti et al., GCN Circ. 42253; Quintana-Ansaldo et al., Circ. GCN 42254; Maksut et al., GCN Circ. 42256; Ghosh et al., GCN Circ. 42261; Quadri et al., GCN Circ. 42262; Adami et al. GCN Circ. 42266; Peretto et al., GCN Circ. 42267; Ruocco et al., GCN Circ. 42269; Calapai, GCN Circ. 42275; and Adami et al. GCN Circ. 42276) with preliminary magnitudes of: g = 21.59 +/- 0.04 r = 21.29 +/- 0.04 z = 20.93 +/- 0.07 We measure a g-r color of 0.30 +/- 0.06, which is consistent with the color of 0.31 +/- 0.01 at about 2 hours after the trigger reported by Palmerio et al. (GCN Circ. 42229), but significantly different to the color of -0.18 +/- 0.12 at about 28 hours after the trigger reported by Adami et al. (GCN Circ. 42276). 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/42279. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40351] GRB 251014A: Swift-BAT refined analysis
by GCN Circulars 15 Oct '25

15 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42278 SUBJECT: GRB 251014A: Swift-BAT refined analysis DATE: 25/10/15 01:35:52 GMT FROM: Rahul Gupta at NASA GSFC <rahul.gupta(a)nasa.gov> M. J. Moss (GSFC), E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 251014A (trigger #1403878) (Ambrosi, et al., GCN Circ. 42238). The BAT ground-calculated position is RA, Dec = 111.728, 6.420 deg which is RA(J2000) = 07h 26m 54.7s Dec(J2000) = +06d 25' 10.7" with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 78%. The BAT mask-weighted light curve shows a single peaked emission with total duration of less than 2 sec. T90 (15-350 keV) is 1.56 +- 0.24 sec (estimated error including systematics). The time-averaged spectrum from T-0.07 to T+1.82 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.82 +- 0.70, and Epeak of 47.1 +- 9.2 keV (chi squared 60.50 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 2.3 +- 0.2 x 10^-07 erg/cm2 and the 1-sec peak flux measured from T-0.07 sec in the 15-150 keV band is 2.8 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.90 +- 0.13 (chi squared 69.47 for 57 d.o.f.). All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1403878 View this GCN Circular online at https://gcn.nasa.gov/circulars/42278. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0