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

[vsnet-grb-info 40334] GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42263 SUBJECT: GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst DATE: 25/10/14 17:05:50 GMT FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu> Samuele Ronchini (GSSI), James DeLaunay (PSU), Aaron Tohuvavohu (Caltech), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (Northwestern) report: Swift/BAT did not localize GRB 251014B onboard (T0: 2025-10-14T04:47:21.17 UTC, Fermi trigger number 782110046). The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The arcmin position of the burst is found with the newly developed pipeline BAT-GLIMPSE: Gamma-ray Localization using Imaging and Mosaic techniques for Pointing and Slew Epochs (Ronchini et. al, in prep). The pipeline makes use of the tools from BatAnalysis (Parsotan et al. 2025). The source is found with an SNR = 8.5 Independently, the BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), confirms the detection of the burst in a 2.048 s analysis time bin starting at T0 - 1.024 s with a sqrt(TS) of 19.78. An arcminute localization is found with DeltaLLHOut of 53.26 and a DeltaLLHPeak of 48.76. See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretations of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. The BAT position is: RA, Dec = 14.5954, -35.5802 deg which is RA(J2000) = 00h 58m 22.90s Dec(J2000) = -35d 34’ 48.7″ with an estimated uncertainty of 3 arcmin radius. More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=782110077 XRT and UVOT follow-up has been requested. Results of follow-up observations will be reported in future circulars. GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/42263. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40333] GRB 251013C: Bassano Bresciano Observatory optical observations
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42262 SUBJECT: GRB 251013C: Bassano Bresciano Observatory optical observations DATE: 25/10/14 16:09:54 GMT FROM: Ulisse Quadri at Bassano Bresciano Observatory <osservatoriobassano(a)gmail.com> U.Quadri, L.Strabla and P.Madurini (Bassano Bresciano Astronomical Observatory) Members of: GRB/UAI - Gamma ray Burst section of Unione Astrofili Italiani. AAVSO - American Association of Variable Star Observers. GAC - Gruppo Astrofili Cremonesi. 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), report: We imaged the field of GRB 251013C detected by SVOM (Rakotondrainibe et al., GCN 42222), with the robotic telescope of (IAU station 565) Bassano Bresciano Observatory, Italy . The observations started 1h 47m after the trigger with our Newton telescope D=440 mm F/D=4.5. We co-added series of 10 exposures of 30 sec each. We clearly detect a bright afterglow 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)) at the following position (+/- 3 arcsec): RA (J2000.0) = 23 03 20.5 DEC(J2000.0) = -00 12 37 We report our photometry analysis: HJD CR Mag Err ----------------------------- 2460962.318647 15.63 0.01 2460962.318647 15.63 0.01 2460962.322293 15.67 0.01 2460962.325915 15.73 0.01 2460962.329549 15.72 0.01 2460962.333183 15.77 0.01 2460962.336817 15.84 0.01 2460962.340463 15.92 0.01 2460962.344097 15.98 0.01 2460962.347730 16.05 0.01 2460962.351307 16.12 0.01 2460962.355022 16.18 0.01 2460962.358656 16.24 0.01 2460962.362302 16.24 0.02 2460962.365947 16.24 0.02 2460962.369581 16.29 0.02 2460962.373227 16.31 0.01 2460962.376873 16.35 0.02 2460962.380507 16.37 0.02 2460962.384141 16.37 0.02 2460962.387775 16.43 0.02 2460962.391397 16.47 0.02 2460962.395032 16.54 0.02 2460962.398665 16.55 0.02 2460962.402299 16.56 0.02 2460962.405933 16.61 0.02 2460962.409568 16.64 0.02 2460962.413190 16.64 0.02 2460962.416824 16.68 0.02 2460962.420458 16.71 0.02 2460962.424092 16.78 0.02 2460962.427715 16.83 0.02 2460962.431349 16.83 0.03 2460962.434982 16.84 0.03 2460962.438617 16.98 0.03 2460962.442251 17.06 0.04 2460962.445885 17.03 0.05 2460962.449519 17.02 0.04 2460962.453153 17.09 0.04 2460962.456787 17.02 0.04 ----------------------------- CR magnitude is unfiltered with R zero point. Magnitudes were estimated with the pan-STARRS cat and are derived using Lupton (2005) equations. Not corrected for galactic dust extinction. Reference: http://www.osservatoriobassano.altervista.org The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42262. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40332] GRB 251013C: Early and late-time optical counterpart detection by LCO
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42261 SUBJECT: GRB 251013C: Early and late-time optical counterpart detection by LCO DATE: 25/10/14 15:45:51 GMT FROM: ankur ghosh at CAPP, University of Johannesburg <ghosh.ankur1994(a)gmail.com> Ankur Ghosh, Soebur Razzaque (CAPP, University of Johannesburg), Rahul Gupta (NASA GSFC), Alexander Moskvitin, Yulia Sotnikova (SAO RAS), Naveen Dukiya (ARIES) on behalf of a larger collaboration. We observed the field of the GRB 251013C triggered by Fermi (Fermi GBM team, GCN circ. 42221), and SVOM (Rakotondrainibe et al., GCN circ. 42222) in V and r filters of the 1-meter Sinistro telescope at the Las Cumbres Observatory Global Telescope (LCOGT) node located at South African Astronomical Observatory (SAAO). The 1-m Sinistro telescope is equipped with a 4K x 4K CCD (FOV: 26 x 26 arcmin, scale: 0.39 arcsec/pixel). Observations began on October 13, 2025, starting from 2.88 hours after the GRB trigger. Further observations are still ongoing. We clearly detect the optical transient (OT) 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), López-Cámara 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)). ------------------------------------------------------------------------------------------------------ |Date| |JDstart| |t-T0 (hours)| |Exp (sec)| |Filter| |Magnitude| ------------------------------------------------------------------------------------------------------ 2025-10-13 2460962.35625 2.88 1 x 300 V V = 16.61 +/- 0.01 2025-10-14 2460963.01397 18.67 1 x 600 V V = 20.73 +/- 0.05 ------------------------------------------------------------------------------------------------------ The field was calibrated against nearby APASS stars, with magnitudes converted using Lupton (2005) equations, and has not been corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/42261. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40331] LIGO/Virgo/KAGRA S251014cn: NED Galaxies in the 3-Initial Localization Volume
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42260 SUBJECT: LIGO/Virgo/KAGRA S251014cn: NED Galaxies in the 3-Initial Localization Volume DATE: 25/10/14 15:45:35 GMT FROM: David Cook at Caltech/IPAC-NED <dcook(a)ipac.caltech.edu> David O. Cook (Caltech/IPAC), Rick Ebert (Caltech/IPAC), George Helou (Caltech/IPAC), Joseph M. Mazzarella (Caltech/IPAC), Marion Schmitz (Caltech/IPAC), and Leo Singer (NASA/GSFC) On behalf of the NASA/IPAC Extragalactic Database (NED) Team. We spatially cross-matched the LVK S251014cn-3-Initial sky localization with the [NED Local Volume Sample](https://ned.ipac.caltech.edu/NED::LVS/) (NED-LVS; Cook et al. 2023), which is a subset of NED with a redshift or redshift-independent distance less than 1000 Mpc. We find 10691 galaxies within the 90% containment volume, and we list here the top 20 galaxies sorted by the joint probability of the 3D localization and the WISE W1 luminosity (an observable proxy for stellar mass). For the full or top 20 list of galaxies in the 90% volume go either to the NED Gravitational Wave Followup service at https://ned.ipac.caltech.edu/uri/NED::GWF/ or click on the following links: Full List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S251014cn/3 Top 20 List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S251014cn/3/20 The NED-GWF service provides downloadable galaxy lists and visualizations for candidate host galaxies. For each GW alert, these products are automatically generated and made available within minutes to expedite efficient electromagnetic follow-up observations. The NED top 20 list is sorted by the joint probability of the 3D localization and the WISE W1 luminosity, but users can sort on additional pre-computed prioritization metrics (star formation rate, P_3D * P_SFR; and specific star formation rate, P_3D * P_sSFR; etc.) which are available via downloading the entire galaxy list inside the event's probability volume. | objname| ra| dec|objtype| DistMpc|DistMpc_unc| m_NUV| m_NUV_unc| m_Ks| m_Ks_unc| m_W1| m_W1_unc| P_3D|P_3D_LumW1| |-------------------------|--------------|--------------|-------|-----------|-----------|------------|------------|------------|------------|------------|------------|--------|----------| |WISEA J204706.11-222948.1| 311.77550| -22.49672| G| 727.73| 4.31| null| null| 14.677| 0.171| 9.127| 0.006|1.25e-07| 1.19e-09| |WISEA J210442.39-250658.2| 316.17666| -25.11619| G| 632.49| 0.65| null| null| 12.233| 0.093| 9.702| 0.006|1.67e-07| 7.14e-10| | [HB89] 2155-304| 329.71694| -30.22559| QSO| 546.26| 0.43| 13.401| 0.001| 10.101| 0.013| 9.233| 0.006|8.29e-08| 4.03e-10| |WISEA J203200.13-212013.9| 308.00055| -21.33721| G| 686.01| null| null| null| 13.471| 0.172| 11.048| 0.007|2.64e-07| 3.82e-10| |WISEA J195711.85-155450.4| 299.29942| -15.91401| G| 464.26| null| null| null| 13.148| 0.182| 9.223| 0.006|9.41e-08| 3.41e-10| |WISEA J210053.37-260056.2| 315.22239| -26.01562| G| 523.86| null| 20.640| 0.211| 13.660| 0.182| 10.671| 0.006|2.12e-07| 2.55e-10| |WISEA J202657.64-194510.3| 306.74020| -19.75287| G| 536.72| 0.65| null| null| 12.502| 0.088| 10.962| 0.006|2.42e-07| 2.33e-10| |WISEA J233456.39-265518.6| 353.73499| -26.92184| G| 280.74| 0.65| null| null| 11.229| 0.056| 8.467| 0.005|8.37e-08| 2.18e-10| |WISEA J195521.91-151547.2| 298.84130| -15.26312| G| 485.70| null| null| null| 13.338| 0.163| 10.223| 0.007|1.19e-07| 1.91e-10| |WISEA J211913.50-272622.9| 319.80626| -27.43970| G| 533.96| null| 21.251| 0.278| 13.385| 0.135| 11.169| 0.007|2.33e-07| 1.84e-10| |WISEA J201311.18-190314.5| 303.29661| -19.05404| G| 572.05| null| null| null| 13.451| 0.145| 11.150| 0.007|1.75e-07| 1.62e-10| |WISEA J202635.83-202306.5| 306.64930| -20.38515| G| 735.83| 0.65| null| null| 12.556| 0.102| 11.879| 0.008|2.08e-07| 1.62e-10| |WISEA J202559.97-203159.0| 306.49991| -20.53307| G| 732.69| 0.65| null| null| 12.200| 0.114| 11.897| 0.012|2.03e-07| 1.54e-10| |WISEA J214110.24-264550.3| 325.29269| -26.76397| QSO| 608.68| null| 16.698| 0.017| 11.077| 0.012| 9.482| 0.006|3.03e-08| 1.46e-10| |WISEA J204622.40-223419.0| 311.59335| -22.57195| G| 685.98| 4.31| null| null| 15.453| 0.346| 11.646| 0.007|1.74e-07| 1.46e-10| |WISEA J200050.95-154454.3| 300.21230| -15.74842| G| 688.87| null| null| null| 13.684| 0.252| 11.792| 0.008|1.90e-07| 1.41e-10| |WISEA J193249.64-101803.3| 293.20684| -10.30092| G| 410.47| 0.65| null| null| 12.248| 0.139| 9.373| 0.006|5.53e-08| 1.39e-10| |WISEA J210524.13-254016.4| 316.35056| -25.67124| G| 492.45| null| null| null| 13.568| 0.159| 11.429| 0.007|2.62e-07| 1.38e-10| |WISEA J202206.73-184638.7| 305.52808| -18.77742| G| 497.59| 0.65| 19.597| 0.097| 12.293| 0.055| 11.011| 0.007|1.75e-07| 1.38e-10| |WISEA J201415.46-192535.3| 303.56468| -19.42654| G| 602.46| null| null| null| 13.720| 0.165| 11.210| 0.007|1.39e-07| 1.35e-10| Table 1: Top 20 galaxies in NED-LVS that fall in the 90% probability volume for S251014cn sorted by the joint probability of 3D position and WISE W1 luminosity (P_3D * P_LumW1). Galaxy is the NED preferred name. RA and Dec are the Equatorial coordinates in degrees (J2000). Objtype is the object type of the galaxy candidate. Distance is the distance to the galaxy in Mpc. m_NUV and mErr_NUV are the apparent magnitude and error from GALEX. m_Ks and mErr_Ks are the apparent magnitude and error from 2MASS. m_W1 and mErr_W1 are the apparent magnitude and error from AllWISE. P_3D is the probability that the galaxy is in the volume given the distance of GW event. P_3D_LumW1 is the joint probability within the volume weighted by the WISE1 luminosity of the galaxy (P_3D * P_LumW1). View this GCN Circular online at https://gcn.nasa.gov/circulars/42260. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40330] GRB 251013C: Fermi GBM Observation
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42259 SUBJECT: GRB 251013C: Fermi GBM Observation DATE: 25/10/14 15:35:36 GMT FROM: Jacob Smith at Fermi-GBM Team <jrs0118(a)uah.edu> Jacob Smith (UAH), E. Palafox (INAOE), and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 17:39:41.94 UT on 13 October 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251013C (trigger 782069986/251013736), which was also detected by SVOM (N. A. Rakotondrainibe et al. 2025, GCN 42222) and Swift XRT (P.A. Evans et al. 2025, GCN 42232). The Fermi GBM on-ground location is consistent with the Swift BAT position. NOT measured a spectroscopic redshift z = 0.572 (A. Martin-Carrillo et al. 2025, GCN 42227). The angle from the Fermi LAT boresight is 60 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 12 s (50-300 keV). The time-averaged spectrum from T0-0.1 to T0+4.0 s is best fit by a simple power law function with index -1.50 +/- 0.02. A Comptonized function fits equally well with Epeak = 7291.00 +/- 4840.00 and alpha = -1.46 +/- 0.03. The event fluence (10-1000 keV) in this time interval is (2.4 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.32 s in the 10-1000 keV band is 5 +/- 0.2 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/42259. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40329] GRB 251013D: Swift ToO observations
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42258 SUBJECT: GRB 251013D: Swift ToO observations DATE: 25/10/14 15:22:30 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 251013D. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021861 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/42258. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40328] GRB 251014A: DDOTI Upper Limit
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42257 SUBJECT: GRB 251014A: DDOTI Upper Limit DATE: 25/10/14 13:52:43 GMT FROM: Rosa Leticia Becerra Godínez at Tor Vergata, Roma <rbecerra(a)astro.unam.mx> Rosa L. Becerra (U Roma), Alan M. Watson (UNAM), Camila Angulo Valdez (UNAM), Sahil Atri (U Roma), Nat Butler (ASU), Simone Dichiara (Penn State University), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl López (UNAM), Margarita Pereyra (UNAM) and Eleonora Troja (U Roma) report: We observed the field of GRB 251014A detected by Fermi/GBM (Fermi GBM Team, GCN Circ. 42237) and Swift (Ambrosi et al., GCN Circ. 42238) with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir (http://ddoti.astroscu.unam.mx) on the night of 2025-10-14 UTC. DDOTI observed the Swift/BAT position (Ambrosi et al., GCN Circ. 42238) from 09:12 UTC to 12:27 UTC (from T+8.7 h to T+ 11.9 h after the trigger), obtaining a total exposure of 70 minutes, alternating with other scientific programs. Comparing our observations to the USNO-B1 and Pan-STARRS PS1 DR2 catalogues, we detect no uncatalogued fading sources within the observed field down to a 5-sigma limiting AB magnitude of: w >20.3 This value is consistent with the reported by the SAO RAS collaboration (Moskvitin et al. GCN Circ. 42250) and is not corrected for the Galactic extinction. We thank the staff of the Observatorio Astronómico Nacional on the Sierra of San Pedro Mártir. View this GCN Circular online at https://gcn.nasa.gov/circulars/42257. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40327] GRB 251013C NUTTelA-TAO / BSTI Early Measurements
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42256 SUBJECT: GRB 251013C NUTTelA-TAO / BSTI Early Measurements DATE: 25/10/14 13:45:06 GMT FROM: Zhanat Maksut at Nazarbayev University <zhanat.maksut(a)nu.edu.kz> Z. Maksut (NU), B. Grossan (UCB, NU), T. Komesh (NU), D. Berdikhan (NU), M. Krugov (FAI) and E. Abdikamalov (NU) report on behalf of the Energetic Cosmos Laboratory: The Nazarbayev University Transient Telescope at Assy-Turgen Astrophysical Observatory (NUTTelA-TAO) pointed at GRB 251013C on receipt of an automated GCN SVOM/ECLAIRs position alert, with the Burst Simultaneous Three-Channel Imager (BSTI; Grossan, Kumar & Smoot 2019, JHEA, 32, 14). We started observations at UT 2025 October 13, 17:41:17, 95 s after the ECLAIRs trigger (N. A. Rakotondrainibe, et. al., GCN 42222). Observations were made in conditions that started good and deteriorated to cloudy over the night. A new and changing source consistent with the XRT position (P.A. Evans et al., GCN 42232) was detected. Note that these observations provide essentially full-time coverage until conditions deteriorated, about 3 hours of coverage. The source was off our field in g' and r' band cameras, but on the sensor with adequate margin in our Sloan i' camera. We report the following preliminary, uncorrected, selected photometric values for the optical transient: tc-t0(s) texp i'(mag) err(mag) -------- ------ ------- -------- 96 3.0 13.67 0.1 123 3.0 14.20 0.1 141 3.0 14.27 0.1 185 30.0 14.69 0.06 245 30.0 14.96 0.06 305 30.0 15.16 0.06 425 30.0 15.06 0.06 635 30.0 15.14 0.06 tc-t0 = trigger time minus image center time. Calibration was done with 5 bright Pan-STARRS catalog stars on our images (see Komesh, T. et al. 2023, MNRAS 520, 6104). We find a rapid fading to a plateau starting at ~300 s. We caution the reader that these are preliminary results, without color or other corrections, and will likely change. Please also note that times are approximate. Systematic errors are estimated from previous measurements. We welcome requests for additional data. ---------------------------------- NU = Nazarbayev University, Astana, Kazakhstan UCB = University of California, Berkeley, USA FAI = Fesenkov Astrophysical Institute, Kazakhstan This research has been funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. AP26103591). The NUTTelA-TAO Team acknowledges the support of the staff of the Assy-Turgen Astrophysical Observatory, Almaty, Kazakhstan, and the Fesenkov Astrophysical Institute, Almaty, Kazkhstan. View this GCN Circular online at https://gcn.nasa.gov/circulars/42256. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40326] LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42255 SUBJECT: LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate DATE: 25/10/14 12:32:53 GMT FROM: Matteo Tagliazucchi at University of Bologna - INFN Bologna <matteo.tagliazucchi2(a)unibo.it> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S251014cn during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2025-10-14 11:33:23.373 UTC (GPS time: 1444476821.373). The candidate was found by the Aframe [1], cWB [2], cWB BBH [3], GstLAL [4], MBTA [5], MLy [6], PyCBC Live [7], and SPIIR [8] analysis pipelines. S251014cn is an event of interest because its false alarm rate, as estimated by the online analysis, is 3.2e-10 Hz, or about one in 1e2 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S251014cn The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), BNS (<1%), or NSBH (<1%). Assuming the candidate is astrophysical in origin, the probability that at least one of the compact objects is consistent with a neutron star mass (HasNS) is <1%. [9] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [9] Both HasNS and HasRemnant consider the support of several neutron star equations of state for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is <1%. The source chirp mass falls with highest probability in the bin (11.0, 22.0) solar masses, assuming the candidate is astrophysical in origin. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [10], distributed via GCN and SCiMMA notices about 24 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [10], distributed via GCN and SCiMMA notices about 5 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 233 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 610 +/- 172 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Marx et al. PRD 111, 042010 (2025) doi:10.1103/PhysRevD.111.042010 [2] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004 [3] T. Mishra et al. PRD 105, 083018 (2022) doi:10.1103/PhysRevD.105.083018 [4] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. PRD 109, 042008 (2024) doi:10.1103/PhysRevD.109.042008 [5] Alléné et al. CQG 42, 105009 (2025) doi:10.1088/1361-6382/add234 [6] Skliris et al. PRD 110, 104034 (2024) doi:10.1103/PhysRevD.110.104034 [7] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [8] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023 [9] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [10] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/42255. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40325] GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42254 SUBJECT: GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory DATE: 25/10/14 12:02:29 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf(a)iac.es> M. Quintana-Ansaldo, J. Basurto Merino, P.G. Berdayes, A. Caballero-Almagro, A. Cerón, M. Contreras, F. Díaz-Segado, T. Ferrer-Laviña, B. Gandolfi, V. Ghiraldo, J. Hernández Fung, L. Juliá-Maroto, E. Lekaroz-Urriza, M. Manzano García, E. Mejía-Martínez, J. Prieto Polo, M. Pulido-Torres, , A. Schenone-Zanuzzi, A. Selezneva, T. Tundidor Rodríguez, E. Urquijo-Rodríguez (all ULL), M. Abdul-Masih (IAC and ULL), and I. Pérez-Fournon (IAC and ULL). Following the detection of GRB 251013C by Fermi (Fermi GBM team, GCN circ. 42221), and SVOM (Rakotondrainibe et al., GCN circ. 42222), we observed the field with the Las Cumbres Observatory (LCO) 40-cm telescope (a Planewave Delta Rho 350 telescope equipped with a CMOS QHY600 camera) located at the LCO node at Sutherland Observatory (South Africa). The observation, a single exposure of 300 sec in the SDSS r filter, started on 2025-10-13 at 18:27:18 UT, about 47 minutes after the Fermi and SVOM trigger. The optical counterpart detected by SVOM/VT (Palmerio et al., GCN circ. 42223) is clearly detected in our image with a magnitude of r = 14.84 +/- 0.02 (AB), calibrated against PanSTARRS-1 DR2 and not corrected for galactic extinction. This result confirms the rebrightening reported by Konno et al. (GCN circ. 42226). Other optical and near-IR detections have been reported by 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), López-Cámara et al. (GCN circ. 42242), Zhang et al. (GCN circ. 42248), and Brosio et al. (GCN circ. 42251). A redshift of z = 0.572 has been measured by Martin-Carrillo et al. (GCN circ. 42227). GRB 251013C has also been detected by Swift-XRT (Evans et al., GCN circ. 42232), AstroSat (Arya et al., GCN circ. 42246), Einstein Probe (Wang et al., GCN circ. 42247), and ALMA Laskar et al. (GCN circ. 42243). Based on observations made with the Las Cumbres Observatory’s education network telescopes that were upgraded through generous support from the Gordon and Betty Moore Foundation (program IAC2025B-010). These observations are part of a course in Astrophysical Techniques of the Master in Astrophysics of the Astrophysics Department of the University of La Laguna in collaboration with the Instituto de Astrofísica de Canarias (La Laguna, Tenerife, Canary Islands, Spain). View this GCN Circular online at https://gcn.nasa.gov/circulars/42254. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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