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

[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…

1 0

[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…

1 0

[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…

1 0

[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…

1 0

[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…

1 0

[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…

1 0

[vsnet-grb-info 40324] GRB 251013C: Asiago optical observations
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42253 SUBJECT: GRB 251013C: Asiago optical observations DATE: 25/10/14 11:40:21 GMT FROM: Andrea Reguitti at INAF - Osservatorio Astronomico di Padova <andreareguitti(a)gmail.com> A. Reguitti (INAF/OAPd) reports on behalf of a larger collaboration: I observed the field of GRB 251013C (Fermi GBM Team, GCN 42221; Rakotondrainibe et al., GCN 42222) using the 67/92 Schmidt Telescope located at the Asiago observatory (Italy). Observations were carried out using Sloan r and i filters. The optical counterpart (Palmerio et al., GCN 42223; Perez-Garcia et al., GCN 42225; Konno et al., GCN 42226; Martin-Carrillo et al., GCN 42227; Masi, GCN 42228; Palmerio et al., GCN 42229; Moskvitin et al., GCN 42230; Gompertz et al., GCN 42231; Garnavich, GCN 42240; Watson et al., GCN 42241; López-Cámara et al., GCN 42242; Brosio et al., GCN 42251) is clearly detected in our frames. At mean epoch 2025 Oct 13.85 UT (2.75 hr after the GRB), I measure AB magnitudes r = 16.51 +- 0.05 and i = 16.27 +- 0.04 (calibrated against magnitudes from the Pan-STARRS catalog). View this GCN Circular online at https://gcn.nasa.gov/circulars/42253. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40323] GRB 251013A: CALET Gamma-Ray Burst Monitor detection
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42252 SUBJECT: GRB 251013A: CALET Gamma-Ray Burst Monitor detection DATE: 25/10/14 11:06:25 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University <kawakubo(a)phys.aoyama.ac.jp> S. Sugita, A. Yoshida, T. Sakamoto, Y. Kawakubo (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena), and the CALET collaboration: The GRB 251013A (Fermi GBM Final Real-time Localization: Fermi GBM team, GCN Circ. 42213; SVOM/GRM observation: Wang et al., GCN Circ. 42218) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 08:04:04.90 UTC on 13 October 2025 (https://cgbm.calet.jp/cgbm_trigger/flight/1444377382/index.html) The burst signal was seen by only the SGM detector. The burst light curve shows a single pulse that starts at T+0.55 sec, peaks at T+1.32 sec, and ends at T+1.85 sec. The T90 and T50 durations measured by the SGM data are 1.20 +/- 0.16 sec and 0.50 +/- 0.11 sec (40-1000 keV), respectively. The ground-processed light curve is available at https://cgbm.calet.jp/cgbm_trigger/ground/1444377382/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at Waseda University. View this GCN Circular online at https://gcn.nasa.gov/circulars/42252. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40322] GRB 251013C: ABObservatory afterglow detection
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42251 SUBJECT: GRB 251013C: ABObservatory afterglow detection DATE: 25/10/14 10:53:56 GMT FROM: A. Brosio at ABObservatory Rosarno <antonino.brosio(a)gmail.com> A. Brosio (ABObservatory Rosarno), M. A. Tripodi (ABObservatory Rosarno), S. Savaglio (University of Calabria), G. Bracco, P. Cianfarra, L. Sangaletti, S. Tosi & S. Zappatore (University of Genoa), S. Benatti & M. G. Guarcello (INAF Palermo), L.Cabona, M. Rainer, F. M. Zerbi, M. Basilicata (INAF Brera), D. Ricci (INAF Padova), A. Di Dato (INAF Capodimonte), S. Masiero & A. Nastasi (GAL Hassin), D. Liguori (Osservatorio "G. Galilei" Cariati), L. Betti (Osservatorio Polifunzionale del Chianti), R. Nesci (Associazione Astronomica Antares APS di Foligno), for the NOCTIS team report We observed the field of GRB 251013C, which was detected by Fermi GBM team (GCN 42221) with the 30-cm automated telescope at ABObservatory (Rosarno, Italy) in V filter. The observations began on 2025 october 13 at 20:56:53 UT, approximately 2.38 hours after the trigger. The observation consisted of 50 exposures of 120 seconds each,with good sky conditions. The mid-exposure time was 22:12:46 UT, and the final exposure ended at 23:32:52 UT. From photometry, we detect the optical counterpart in our images at the following coordinates: R.A (J2000.0) = 23 03 19.712 Dec. (J2000.0) = -00 12 53.17 The measured magnitude at JD 2460962.37284 is: 16.86 +/- 0.06 in V band with SNR 14.98 (AB, calibrated with the GAIA DR3 on SIMBAD). We also obtained a decay curve which, during the period we monitored the object, showed a decline down to magnitude +17.848 +/-0.275 at 23:27:57 UT View this GCN Circular online at https://gcn.nasa.gov/circulars/42251. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40321] GRB 251014A: SAO RAS optical upper limit
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42250 SUBJECT: GRB 251014A: SAO RAS optical upper limit DATE: 25/10/14 10:06:03 GMT FROM: Alexander Moskvitin at SAO RAS <mosk(a)sao.ru> A. S. Moskvitin, O. I. Spiridonova (SAO RAS), report on behalf of GRB follow-up team. We observed the field of the GRB 251014A (Ambrosi et al., GCN 42238; The Fermi GBM team, GCN 42237; de Barra et al., GCN 42249) with the 1-m SAO RAS telescope Zeiss-1000 equipped with the CCD-photometer. We obtained 7 x 300 sec. images in Rc band under mediocre weather conditions on 2025.10.14, 00:51:01--01:38:56 UT (t_mid - T0 = 0.77458 hours). Within our FOV (covers ~80% of northern part of Swift-BAT error circle) we do not detect any new source down to the limiting magnitude of R_lim = 21.5. The field calibrated against nearby USNO-B1.0 stars (R2 magnitudes) and not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/42250. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0