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

[vsnet-grb-info 40294] GRB 251013D: Fermi GBM Final Real-time Localization
by GCN Circulars 13 Oct '25

13 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42224 SUBJECT: GRB 251013D: Fermi GBM Final Real-time Localization DATE: 25/10/13 18:27:33 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 18:17:00 UT on 13 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251013D (trigger 782072225.388414 / 251013762). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 44.4, Dec = 10.2 (J2000 degrees, equivalent to J2000 02h 57m, 10d 11'), with a statistical uncertainty of 5.4 degrees. The angle from the Fermi LAT boresight is 73.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251013762/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251013762/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251013762/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42224. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40293] GRB 251013C: SVOM/VT optical observation
by GCN Circulars 13 Oct '25

13 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42223 SUBJECT: GRB 251013C: SVOM/VT optical observation DATE: 25/10/13 18:18:36 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> J. T. Palmerio (CEA/Irfu), Ny Avo Rakotondrainibe, C. Adami (LAM), H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu (NAOC) report on behalf of the SVOM/VT team: After the trigger by SVOM/ECLAIRs at 2025-10-13T17:39:42 UTC (T0), SVOM performed an automatic slew on the burst location (Rakotondrainibe et al., GCN 42222). SVOM/VT began observing the field at 2025-10-13T17:44:04, 261.08 seconds after T0, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. From a preliminary analysis of the 1-bit subimage and source list downloaded via VHF network, at least one credible candidate is identified, the details of which are presented below. VT_ID 117: This bright candidate was flagged as a catalogued source but significantly brighter than its catalogued magnitude. The position of this candidate is R.A., Dec. 345.8356, -0.2103 degrees, corresponding to: R.A. (J2000) = 23h03m20.6s Dec. (J2000) = -0d12m37.1s with an uncertainty of 0.5 arcsec. This location is within the R90 uncertainty region of the SVOM/MXT onboard localization. The source was detected in both VT_R and VT_B. The candidate's magnitudes are: | date-obs (UTC) | mid-time | exposure | band | mag(AB) | | -------------------- | ----------- | --------- | ----- | ------------- | | 2025-10-13T17:44:04 | 6.85 min | 6*50 sec | VT_B | 15.38 ± 0.01 | | 2025-10-13T17:44:04 | 6.85 min | 6*50 sec | VT_R | 14.76 ± 0.01 | Magnitudes were not corrected for dust extinction. The VT color of the counterpart suggests it is not very high redshift or highly extinguished. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/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/42223. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40292] GRB 251013C: SVOM detection of a burst
by GCN Circulars 13 Oct '25

13 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42222 SUBJECT: GRB 251013C: SVOM detection of a burst DATE: 25/10/13 18:17:34 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> N. A. Rakotondrainibe, C. Adami (LAM), D. Turpin, D. Götz (CEA/Irfu), H. Yang (IRAP) At 2025-10-13T17:39:42 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251013C (SVOM burst-id sb25101311) also detected by Fermi/GBM (Fermi GBM team GCN 42221). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 16 alerts. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 35.62 in the [8-120] keV energy band over a time window of 10.24 seconds starting at 2025-10-13T17:39:42. The SVOM/ECLAIRs light curve showed a single peak structure of a T90 duration of 17.1 (+6.9/-1.5) s. The localization of the best alert is R.A., Dec. 345.8809, -0.1698 degrees (J2000) with a 90% confidence level (C.L.) radius of 2.94 arcmin (including systematic error of 2 arcmin added in quadrature). This burst also triggered SVOM/GRM at 2025-10-13T17:39:43 on a timescale of 18 seconds with an SNR of 11. SVOM slewed to the burst. SVOM/MXT began observing the field at 2025-10-13T17:43:05 UTC, 203 seconds after T0. Using onboard processed data we found an uncatalogued X-ray source located at R.A., Dec. 345.8301, -0.2207 degrees: R.A. (J2000) = 23h03m19s Dec. (J2000) = -0d13m14s with a 90% C.L. radius of 69 arcseconds. This location is 4.31 arcminutes from the ECLAIRs onboard position. This position may be improved as more data is received. VT began observing the field after the slew. The analysis of the data will be published in a future circular. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Ny Avo Rakotondrainibe: ny-avo.rakotondrainibe(a)lam.fr Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42222. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40291] GRB 251013C: Fermi GBM Final Real-time Localization
by GCN Circulars 13 Oct '25

13 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42221 SUBJECT: GRB 251013C: Fermi GBM Final Real-time Localization DATE: 25/10/13 17:50:11 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 17:39:41 UT on 13 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251013C (trigger 782069986.941944 / 251013736). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 348.9, Dec = -6.3 (J2000 degrees, equivalent to J2000 23h 15m, -6d 17'), with a statistical uncertainty of 5.0 degrees. The angle from the Fermi LAT boresight is 65.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251013736/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251013736/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251013736/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42221. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40290] LIGO/Virgo/KAGRA S251013x: Updated Sky localization and Source Classification
by GCN Circulars 13 Oct '25

13 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42220 SUBJECT: LIGO/Virgo/KAGRA S251013x: Updated Sky localization and Source Classification DATE: 25/10/13 16:23:04 GMT FROM: Nihar.Gupte(a)aei.mpg.de The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S251013x (GCN Circular 42212). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S251013x For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 1361 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 3775 +/- 1200 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] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/42220. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40289] GRB 251013B: SVOM/GRM observation
by GCN Circulars 13 Oct '25

13 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42219 SUBJECT: GRB 251013B: SVOM/GRM observation DATE: 25/10/13 15:20:56 GMT FROM: Yue Wang <m18509381757(a)163.com> SVOM/GRM team: Yue Wang, Chen-Wei Wang, Wen-Jun Tan, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Stéphane Schanne (CEA), Hui Yang (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered on-ground by GRB 251013B at 2025-10-13T08:24:36.250 (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN #42215). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of mutli-peaks with a T90 of 55 +16/-7 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251013B.png In addition, the position of this burst, as determined by Fermi/GBM (RA=356.5, DEC=7.5, GCN #42215), is located at about 68.2 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0-30 to T0+50 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.63 +0.10/-0.13 and the cutoff energy, parameterized as Epeak, is 324 +567/-129 keV. The event fluence (10-1000 keV) in this time interval is (1.08 +0.09/-0.11)E-05 erg/cm^2. The localization of GRB 251013B in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb251013B_amati.png 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. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM/GRM point of contact for this burst is: Yue Wang (IHEP) (yuewang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/42219. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40288] GRB 251013A: SVOM/GRM observation
by GCN Circulars 13 Oct '25

13 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42218 SUBJECT: GRB 251013A: SVOM/GRM observation DATE: 25/10/13 15:18:58 GMT FROM: Yue Wang <m18509381757(a)163.com> SVOM/GRM team: Yue Wang, Chen-Wei Wang, Wen-Jun Tan, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Stéphane Schanne (CEA), Hui Yang (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered both in-flight by GRB 251013A (SVOM trigger reference: sb25101308) at 2025-10-13T08:04:05.800 (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN #42213). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a single pulse with a T90 of 3.5 +0.9/-0.6 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251013A.png In addition, the position of this burst, as determined by Fermi/GBM (RA=19.9, DEC=-1.6, GCN #42213), is located at about 57 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. Marginal signal seen by ECLAIRs through the shields With this localization, the time-averaged spectrum from T0-2 to T0+4 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -0.68 +0.13/-0.13 and the cutoff energy, parameterized as Epeak, is 142 +15/-12 keV. The event fluence (10-1000 keV) in this time interval is (2.96 +0.19/-0.17)E-06 erg/cm^2. The localization of GRB 251013A in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb251013A_amati.png 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. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM/GRM point of contact for this burst is: Yue Wang (IHEP) (yuewang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/42218. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40287] GRB 251003A: Mondy optical upper limit
by GCN Circulars 13 Oct '25

13 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42217 SUBJECT: GRB 251003A: Mondy optical upper limit DATE: 25/10/13 14:51:03 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), N. Pankov (HSE, IKI), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We performed optical observations of the field of GRB 251003A, detected by Fermi (Fermi team, GCNC 42069) and Swift (Beardmore et al., GCNC 42070), in the R-filter with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy). The observations began on 2025-10-06 13:10 UT, i.e. ~3.5 days since the trigger and consisted of 90 exposures by 80 s each. The optical source reported previously (Aceituno et al., GCN 42072; Méndez et al., GCN 42073; Strausbaugh et al., GCN 42074; Freeberg et al., GCN 42085; Sanchez-Ramirez et al., GCN 42086; Worssam et al., GCN 42094; Schneider et al., GCN 42095; Mo et al., GCN 42106; Konno et al., GCN 42126) is not detected in the stacked frame. The preliminary photometry is based on nearby USNO-B stars (R2 magnitudes) and is the following: Date UT start t-T0 Exp. Filter OT Err. UL (mid, days) (n*s) (3sigma) 2025-10-06 13:10:16 3.50116 90*80 R n/d n/d 22.0 View this GCN Circular online at https://gcn.nasa.gov/circulars/42217. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40286] MASTER OT J011025.98-583210.6 : SVOM/VT optical observation
by GCN Circulars 13 Oct '25

13 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42216 SUBJECT: MASTER OT J011025.98-583210.6 : SVOM/VT optical observation DATE: 25/10/13 14:25:57 GMT FROM: Yinuo Ma <mayn(a)bao.ac.cn> Y. N. Ma, L. P. Xin, H. L. Li, Z. H. Yao, 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 (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team. SVOM/VT performed a Target of Opportunity observation of MASTER OT J011025.98-583210.6 (Kechin et al., GCN 42211). SVOM/VT began observing the field at 2025-10-13T04:48:11 UTC in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. With X-band data, at the position of the optical transient (Kechin et al., GCN 42211) we don't detect any uncatalogued source, compared to the Legacy survey. But we noticed that there is a catalogued red source with an angular distance of 1.0 seconds from the source reported (Kechin et al., GCN 42211). The position is R.A.=01:10:26.11, DEC. = -58:32:10.49, J2000. The brightness was 20.31+/-0.07 in VT_R band, but VT_B>23 mag. The analysis showed that this source was stable during our 3.7 hours observation. Our photometry was not corrected for Galactic extinction. Given the source with red color at the position which is very near the MASTER OT J011025.98-583210.6, it is possible associated. A stellar flare from this late type star is possible. 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/42216. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40285] GRB 251013B: Fermi GBM Final Real-time Localization
by GCN Circulars 13 Oct '25

13 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42215 SUBJECT: GRB 251013B: Fermi GBM Final Real-time Localization DATE: 25/10/13 08:33:39 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 08:24:27 UT on 13 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251013B (trigger 782036672.403254 / 251013350). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 356.5, Dec = 7.5 (J2000 degrees, equivalent to J2000 23h 45m, 7d 30'), with a statistical uncertainty of 5.7 degrees. The angle from the Fermi LAT boresight is 87.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251013350/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251013350/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251013350/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42215. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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