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

[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…

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[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…

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[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…

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[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…

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[vsnet-grb-info 40320] GRB 251014A: Fermi GBM Observation
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42249 SUBJECT: GRB 251014A: Fermi GBM Observation DATE: 25/10/14 09:45:29 GMT FROM: Cuán de Barra at UCD <cuan.debarra(a)ucdconnect.ie> C. de Barra (University College Dublin), J. Smith (UAH), C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 00:28:30.34 UT on 14 October 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251014A (trigger 782094515/251014020). which was also detected by Swift BAT (E. Ambrosi et al. 2025, GCN 42238). The Fermi GBM on-ground location is consistent with the Swift BAT position. The angle from the Fermi LAT boresight is 44 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 1.7 s (50-300 keV). The time-averaged spectrum from T0-0.2 to T0+1.7 s is best fit by a simple power law function with index -1.78 +/- 0.06. The event fluence (10-1000 keV) in this time interval is (6.2 +/- 0.5)E-07 erg/cm^2. The 64-ms peak photon flux measured starting from T0+0.32 s in the 10-1000 keV band is 6 +/- 1 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/42249. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40319] GRB 251013C: J band observations by SYSU 80cm infrared telescope
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42248 SUBJECT: GRB 251013C: J band observations by SYSU 80cm infrared telescope DATE: 25/10/14 07:17:23 GMT FROM: zhanghr33(a)mail2.sysu.edu.cn Hao-Ran Zhang, Chen Chun, Duo-Le Cao, Zhong-Nan Dong, Wei-Sen Huang, Jin-Ji Li, Jia-Qi Lin, Pu Lin, Yan Yu, Hao-Nan Yang, P H Thomas Tam, Rong-Feng Shen, Bin Ma (Sun Yat-sen University) report on behalf of the SYSU 80cm infrared telescope team: We observed the field of GRB 251013C detected by SVOM (N. A. Rakotondrainibe et al., GCN 42222) and Fermi (Fermi GBM Team, GCN 42221), using the Sun Yat-sen University 80cm infrared telescope with 20 s exposures in J band. The calculated position is R.A. = 345.8301 deg, Dec = -0.2207deg J2000, from SVOM observation. Our observations began at 2025-10-13 18:03:42 UTC, 0.41 hours after the SVOM trigger. We clearly detect an infrared counterpart at the position of the optical afterglow (J. T. Palmerio et al., GCN 42223; I. Perez-Garcia et al., GCN 42225; R. Konno et al., GCN 42226; L. A. Martin-Carrillo et al., GCN 42227; Gianluca Masi, GCN 42228; J. T. Palmerio et al., GCN 42229; A. S. Moskvitin et al., GCN 42230; B. P. Gompertz et al., GCN 42231; V.Lipunov et al., GCN 42235; P. Garnavich, GCN 42240; Alan M. Watson et al., GCN 42241; Diego López-Cámara et al., GCN 42242). The earliest detection is confirmed at 2025-10-13 18:03:42UTC (T – T0 = 0.41 h) with J mag: 13.49+/-0.14 (Vega system). Preliminary photometry shows a rise of ~0.4mag at 18:26:00UTC (T – T0 = 0.78 h), followed by a rapid decay. The photometric calibration was performed using nearby stars from the 2MASS catalog. The photometric accuracy is limited due to the cloudy weather. The SYSU 80cm infrared telescope is operated and managed by the Department of Astronomy, Sun Yat-sen University. View this GCN Circular online at https://gcn.nasa.gov/circulars/42248. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40318] GRB 251013C: EP-FXT counterpart detection
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42247 SUBJECT: GRB 251013C: EP-FXT counterpart detection DATE: 25/10/14 05:55:24 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> B.T. Wang (YNAO, CAS), H. Zhou (PMO, CAS), Z.M. Wang (BNU), P.Y. Han (HUST), R.X. Hu (WHU), D.Z. Du (ZJU), and C.C. Jin (NAO, CAS) on behalf of the Einstein Probe (EP) team: EP-FXT performed a follow-up observation of the SVOM/ECLAIRs-detected burst GRB 251013C (SVOM/sb25101311, Rakotondrainibe et al., GCN #42222, also detected by Fermi/GBM GCN #42221) at 2025-10-13T19:39:21 (UTC), about 2.0 hours after the SVOM/ECLAIRs trigger, with an exposure time of 1690 s. One uncatalogued source is detected within the ECLAIRs error circle, and the source is spatially consistent with the counterpart reported in optical and X-ray bands (Palmerio et al. GCN #42223, Perez-Garcia et al., GCN #42225, Konno et al., GCN #42226, Masi et al., GCN #42228, Palmerio et al., GCN #42229, Moskvitin et al., GCN #42230, Gompertz et al., GCN #42231, Evans et al., GCN #42232, Garnavich et al., GCN #42240, Watson et al., GCN #42241, López-Cámara et al., GCN #42242) with redshift at 0.572 (Martin-Carrillo et al., GCN #42227). Preliminary analysis on this source are automatically conducted, and details are listed as follows. Source 1: EPF_J230320.5-001237 RA (J2000): 345.8356 Dec (J2000): -0.2103 Flux: 3.75 x 10^-10 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 7.89 x 10^-12 erg/s/cm2 (1 sigma) The position uncertainty of the source is about 10 arcsec in radius (90% C.L. statistical and systematic). 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/42247. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40317] GRB 251013C: AstroSat CZTI detection
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42246 SUBJECT: GRB 251013C: AstroSat CZTI detection DATE: 25/10/14 05:53:26 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> A. Arya (IITB), U. Pathak (IITB), A. Goyal (IITB), Harsha K. H. (IUCAA), M. Tembhurnikar (IUCAA), S. Salunke (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 long GRB 251013C which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 42221), and SVOM/ECLAIRs (Rakotondrainibe et. al., GCN Circ. 42222). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-10-13 17:39:42.75 UTC. The measured peak count rate associated with the burst is 87 (+43, -15) counts/s above the background in the combined data of three quadrants (out of four), with a total of 337 (+89, -97) counts. The local mean background count rate was 202 (+3, -3) counts/s. Using cumulative rates, we measure a T90 of 7.3 (+0.7, -1.1) s. We caution that there is a 0.3 s dead time in the CZTI data just after the burst, hence the actual T90 may be slightly longer. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-10-13 17:39:42.33 UTC. The measured peak count rate associated with the burst is 281 (+68, -36) counts/s above the background in the combined data of all quadrants, with a total of 1351 (+229, -274) counts. The local mean background count rate was 1171 (+6, -9) counts/s. We measure a T90 of 6.7 (+0.8, -1.8) 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/42246. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40316] GRB 251011A: Swift/BAT-GUANO arcminute localization of a burst
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42245 SUBJECT: GRB 251011A: Swift/BAT-GUANO arcminute localization of a burst DATE: 25/10/14 05:15:00 GMT FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com> James DeLaunay (PSU), Aaron Tohuvavohu (Caltech), Jamie A. Kennea (PSU), Samuele Ronchini (GSSI), Gayathri Raman (PSU), Tyler Parsotan (GSFC), Maia Williams (Northwestern) report: Swift/BAT did not localize GRB 251011A onboard (T0: 2024-10-11T03:41:40.09 UTC, Fermi GCN 42195, AstroSat CZTI GCN 42199, Insight-HXMT GCN 42210). The Fermi/GBM 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 burst occurred during a Swift slew. 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). A confident location is found for the burst with SNR of 23.5. The burst is detected in BAT with a duration of ~ 5 seconds. The BAT position is RA, Dec = 4.7878, +45.1894 deg which is RA(J2000) = 00h 19m 09.07s Dec(J2000) = +45d 11’ 21.84″ with an estimated uncertainty of 5 arcmin. This position is consistent with the Ferm/GBM localization (GCN 42195). 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/42245. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40315] GRB 251013D: Swift/BAT-GUANO arcminute localization of a burst
by GCN Circulars 14 Oct '25

14 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42244 SUBJECT: GRB 251013D: Swift/BAT-GUANO arcminute localization of a burst DATE: 25/10/14 04:52:39 GMT FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com> James DeLaunay (PSU), Aaron Tohuvavohu (Caltech), Samuele Ronchini (GSSI), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (Northwestern) report: Swift/BAT did not localize GRB 251013D onboard (T0: 2025-10-13T18:17:00.39 UTC, Fermi Trig 782072225). 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 BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst in a 16.384 s analysis time bin starting at T0 - 0.0 s with a sqrt(TS) of 27.6. An arcminute localization is found with DeltaLLHOut of 159 and a DeltaLLHPeak of 130. 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 = 46.901, 8.800 deg which is RA(J2000) = 03h 07m 36.24s Dec(J2000) = 8d 48’ 00.0″ with an estimated uncertainty of 5 arcmin radius. More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=782072256 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/42244. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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