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[vsnet-grb-info 40691] LIGO/Virgo/KAGRA S251108fi: Updated Sky localization
by GCN Circulars 09 Nov '25

09 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42628 SUBJECT: LIGO/Virgo/KAGRA S251108fi: Updated Sky localization DATE: 25/11/09 08:53:26 GMT FROM: Abhishek Sharma at IIT Gandhinagar <abhishek.sharma(a)ligo.org> 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 S251108fi (GCN Circular 42624). 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/S251108fi For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 528 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2972 +/- 957 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/42628. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40690] LIGO/Virgo/KAGRA S251108dn: Updated Sky localization
by GCN Circulars 09 Nov '25

09 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42627 SUBJECT: LIGO/Virgo/KAGRA S251108dn: Updated Sky localization DATE: 25/11/09 08:48:37 GMT FROM: Abhishek Sharma at IIT Gandhinagar <abhishek.sharma(a)ligo.org> 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 S251108dn (GCN Circular 42619). 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/S251108dn For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 370 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1089 +/- 246 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/42627. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40689] GRB 251108A: Fermi GBM Final Localization Correction
by GCN Circulars 09 Nov '25

09 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42626 SUBJECT: GRB 251108A: Fermi GBM Final Localization Correction DATE: 25/11/09 00:49:37 GMT FROM: Bagrat Mailyan at Florida Tech <mbagrat(a)gmail.com> The Fermi GBM team reports the detection of a likely SHORT GRB "At 21:19:46.26 UT on 08 November 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251108A (trigger 784329591/251108889). This trigger was initially classified as GRB by the flight software. The on-ground calculated location, using the Fermi GBM trigger data, is RA = 144.63, Dec = 8.03 (J2000 degrees, equivalent to J2000 9h 39m, +8d 2'), with a statistical uncertainty of 3.23 degrees. The angle from the Fermi LAT boresight is 10 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251108889/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251108889/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251108889/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/42626. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40688] Fermi trigger No 784329591: Global MASTER-Net observations report
by GCN Circulars 08 Nov '25

08 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42625 SUBJECT: Fermi trigger No 784329591: Global MASTER-Net observations report DATE: 25/11/08 22:16:41 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB251108.89 (trigger No 784329591,09h 39m 43.20s , +04d 40m 48.0s, R=4.06) errorbox 1896 sec after notice time and 1931 sec after trigger time at 2025-11-08 21:51:57 UT, with upper limit up to 16.0 mag. The observations began at zenith distance = 79 deg. The sun altitude is -61.0 deg. The galactic latitude b = 40 deg., longitude l = 231 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3036088 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 1961 | 2025-11-08 21:51:57 | MASTER-Kislovodsk | (09h 27m 10.24s , +08d 52m 53.0s) | C | 60 | 15.4 | 1961 | 2025-11-08 21:51:57 | MASTER-Kislovodsk | (09h 31m 07.31s , +08d 30m 22.5s) | C | 60 | 15.5 | 2041 | 2025-11-08 21:53:17 | MASTER-Kislovodsk | (09h 34m 32.46s , +10d 24m 18.7s) | C | 60 | 16.0 | 2120 | 2025-11-08 21:54:36 | MASTER-Kislovodsk | (09h 24m 35.66s , +07d 00m 49.3s) | C | 60 | 15.4 | 2120 | 2025-11-08 21:54:36 | MASTER-Kislovodsk | (09h 28m 31.61s , +06d 38m 17.4s) | C | 60 | 15.6 | 2361 | 2025-11-08 21:58:36 | MASTER-Kislovodsk | (09h 22m 30.89s , +05d 06m 23.8s) | C | 60 | 15.2 | 2361 | 2025-11-08 21:58:37 | MASTER-Kislovodsk | (09h 26m 26.13s , +04d 43m 50.1s) | C | 60 | 15.4 | 2829 | 2025-11-08 22:06:25 | MASTER-Kislovodsk | (09h 42m 37.63s , +08d 54m 28.6s) | C | 60 | 15.7 | 2829 | 2025-11-08 22:06:25 | MASTER-Kislovodsk | (09h 46m 36.13s , +08d 31m 13.0s) | C | 60 | 15.9 | 2909 | 2025-11-08 22:07:44 | MASTER-Kislovodsk | (09h 21m 08.44s , +03d 14m 02.3s) | C | 60 | 14.8 | 2909 | 2025-11-08 22:07:44 | MASTER-Kislovodsk | (09h 25m 04.69s , +02d 50m 48.6s) | C | 60 | 14.8 | 3148 | 2025-11-08 22:11:43 | MASTER-Kislovodsk | (09h 39m 56.05s , +07d 00m 48.8s) | C | 60 | 15.5 | 3148 | 2025-11-08 22:11:44 | MASTER-Kislovodsk | (09h 43m 53.52s , +06d 37m 32.3s) | C | 60 | 15.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42625. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40687] LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
by GCN Circulars 08 Nov '25

08 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42624 SUBJECT: LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate DATE: 25/11/08 19:45:25 GMT FROM: joshua.freed(a)ligo.org The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S251108fi during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2025-11-08 19:13:28.506 UTC (GPS time: 1446664426.506). The candidate was found by the Aframe [1], cWB [2], cWB BBH [3], GstLAL [4], MBTA [5], and PyCBC Live [6] analysis pipelines. S251108fi is an event of interest because its false alarm rate, as estimated by the online analysis, is 1.3e-12 Hz, or about one in 1e4 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S251108fi The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<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%. [7] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [7] 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 (22.0, 44.0) 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 [8], distributed via GCN and SCiMMA notices about 25 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [8], distributed via GCN and SCiMMA notices about 4 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 1524 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 3537 +/- 1032 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] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [7] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [8] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/42624. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40686] Fermi trigger No 784279167: Global MASTER-Net observations report
by GCN Circulars 08 Nov '25

08 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42623 SUBJECT: Fermi trigger No 784279167: Global MASTER-Net observations report DATE: 25/11/08 16:15:23 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB251108.31 (trigger No 784279167,06h 35m 02.40s , +73d 27m 36.0s, R=4.66) errorbox 29979 sec after notice time and 30021 sec after trigger time at 2025-11-08 15:39:43 UT, with upper limit up to 18.1 mag. The observations began at zenith distance = 61 deg. The sun altitude is -19.5 deg. The galactic latitude b = 25 deg., longitude l = 141 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3035666 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 30051 | 2025-11-08 15:39:43 | MASTER-Kislovodsk | (07h 04m 56.02s , +73d 17m 35.4s) | C | 60 | 17.1 | 30051 | 2025-11-08 15:39:43 | MASTER-Kislovodsk | (07h 18m 49.65s , +72d 53m 17.3s) | C | 60 | 17.6 | 30143 | 2025-11-08 15:41:14 | MASTER-Kislovodsk | (06h 22m 49.76s , +71d 23m 22.2s) | C | 60 | 17.1 | 30144 | 2025-11-08 15:41:15 | MASTER-Kislovodsk | (06h 35m 19.95s , +70d 59m 12.3s) | C | 60 | 17.8 | 30226 | 2025-11-08 15:42:37 | MASTER-Kislovodsk | (06h 12m 21.08s , +73d 19m 19.9s) | C | 60 | 17.3 | 30226 | 2025-11-08 15:42:37 | MASTER-Kislovodsk | (06h 26m 14.47s , +72d 54m 55.0s) | C | 60 | 17.8 | 30306 | 2025-11-08 15:43:57 | MASTER-Kislovodsk | (06h 58m 57.48s , +75d 11m 25.4s) | C | 60 | 17.3 | 30306 | 2025-11-08 15:43:57 | MASTER-Kislovodsk | (07h 14m 33.39s , +74d 46m 47.7s) | C | 60 | 17.8 | 30386 | 2025-11-08 15:45:18 | MASTER-Kislovodsk | (07h 10m 21.00s , +71d 23m 25.8s) | C | 60 | 17.2 | 30386 | 2025-11-08 15:45:18 | MASTER-Kislovodsk | (07h 22m 51.41s , +70d 59m 07.0s) | C | 60 | 17.8 | 30466 | 2025-11-08 15:46:38 | MASTER-Kislovodsk | (05h 59m 42.72s , +75d 13m 28.7s) | C | 60 | 17.4 | 30466 | 2025-11-08 15:46:38 | MASTER-Kislovodsk | (06h 15m 17.99s , +74d 48m 38.2s) | C | 60 | 18.1 | 30546 | 2025-11-08 15:47:57 | MASTER-Kislovodsk | (06h 51m 33.54s , +77d 04m 04.7s) | C | 60 | 17.2 | 30546 | 2025-11-08 15:47:58 | MASTER-Kislovodsk | (07h 09m 18.89s , +76d 38m 56.3s) | C | 60 | 17.8 | 30626 | 2025-11-08 15:49:18 | MASTER-Kislovodsk | (06h 31m 59.52s , +69d 30m 50.0s) | C | 60 | 17.0 | 30626 | 2025-11-08 15:49:18 | MASTER-Kislovodsk | (06h 43m 23.61s , +69d 06m 38.5s) | C | 60 | 17.7 | 30787 | 2025-11-08 15:51:58 | MASTER-Kislovodsk | (05h 43m 40.85s , +77d 09m 58.1s) | C | 60 | 17.0 | 30787 | 2025-11-08 15:51:58 | MASTER-Kislovodsk | (06h 01m 36.06s , +76d 44m 46.8s) | C | 60 | 18.0 | 30867 | 2025-11-08 15:53:19 | MASTER-Kislovodsk | (06h 42m 16.62s , +78d 58m 54.4s) | C | 60 | 17.3 | 30867 | 2025-11-08 15:53:19 | MASTER-Kislovodsk | (07h 03m 02.62s , +78d 33m 30.5s) | C | 60 | 18.0 | 30947 | 2025-11-08 15:54:38 | MASTER-Kislovodsk | (07h 57m 46.40s , +73d 16m 03.6s) | C | 60 | 17.1 | 31045 | 2025-11-08 15:56:17 | MASTER-Kislovodsk | (05h 48m 45.00s , +69d 33m 17.8s) | C | 60 | 17.1 | 31045 | 2025-11-08 15:56:17 | MASTER-Kislovodsk | (06h 00m 11.32s , +69d 08m 50.8s) | C | 60 | 17.5 | 31125 | 2025-11-08 15:57:36 | MASTER-Kislovodsk | (05h 43m 39.70s , +78d 38m 58.2s) | C | 60 | 17.9 | 31204 | 2025-11-08 15:58:56 | MASTER-Kislovodsk | (05h 35m 23.59s , +71d 26m 31.9s) | C | 60 | 17.2 | 31205 | 2025-11-08 15:58:56 | MASTER-Kislovodsk | (05h 47m 57.39s , +71d 01m 58.5s) | C | 60 | 17.7 | 31284 | 2025-11-08 16:00:16 | MASTER-Kislovodsk | (05h 19m 36.38s , +73d 21m 51.5s) | C | 60 | 17.2 | 31284 | 2025-11-08 16:00:16 | MASTER-Kislovodsk | (05h 33m 32.73s , +72d 57m 04.6s) | C | 60 | 17.8 | 31407 | 2025-11-08 16:02:19 | MASTER-Kislovodsk | (07h 57m 57.10s , +71d 20m 23.5s) | C | 60 | 17.1 | 31487 | 2025-11-08 16:03:39 | MASTER-Kislovodsk | (07h 58m 20.11s , +75d 08m 19.9s) | C | 60 | 17.2 | 31567 | 2025-11-08 16:04:59 | MASTER-Kislovodsk | (06h 40m 00.61s , +67d 37m 33.6s) | C | 60 | 17.0 | 31567 | 2025-11-08 16:04:59 | MASTER-Kislovodsk | (06h 50m 28.66s , +67d 13m 08.7s) | C | 60 | 17.5 | 31648 | 2025-11-08 16:06:20 | MASTER-Kislovodsk | (05h 00m 19.14s , +75d 16m 51.6s) | C | 60 | 17.2 | 31648 | 2025-11-08 16:06:20 | MASTER-Kislovodsk | (05h 15m 58.57s , +74d 51m 43.2s) | C | 60 | 17.7 | 31764 | 2025-11-08 16:08:16 | MASTER-Kislovodsk | (07h 59m 35.77s , +77d 04m 16.4s) | C | 60 | 17.2 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42623. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40685] SVOM GRB251108.54: Global MASTER-Net observations report
by GCN Circulars 08 Nov '25

08 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42622 SUBJECT: SVOM GRB251108.54: Global MASTER-Net observations report DATE: 25/11/08 13:42:25 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Tunka robotic telescope [1] located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the SVOM GRB251108.54 (trigger No 1762606617,10h 51m 27.41s , +61d 22m 00.5s, R=1) errorbox 27 sec after notice time and 57 sec after trigger time at 2025-11-08 12:57:54 UT, with upper limit up to 14.6 mag. The observations began at zenith distance = 67 deg. The sun altitude is -32.8 deg. The galactic latitude b = 51 deg., longitude l = 145 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3035823 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 63 | 2025-11-08 12:57:54 | MASTER-Tunka | (10h 52m 29.63s , +61d 58m 59.2s) | P- | 10 | 13.2 | 63 | 2025-11-08 12:57:54 | MASTER- | (10h 51m 53.18s , +62d 04m 17.1s) | C | 10 | 17.1 | 86 | 2025-11-08 12:58:13 | MASTER-Tunka | (10h 52m 29.56s , +61d 59m 00.9s) | P- | 20 | 14.0 | 86 | 2025-11-08 12:58:13 | MASTER- | (10h 51m 53.22s , +62d 04m 17.9s) | C | 20 | 17.3 | 110 | 2025-11-08 12:58:37 | MASTER-Tunka | (10h 52m 29.57s , +61d 59m 01.1s) | P- | 20 | 13.6 | 110 | 2025-11-08 12:58:37 | MASTER- | (10h 51m 53.24s , +62d 04m 18.4s) | C | 20 | 17.5 | 134 | 2025-11-08 12:59:00 | MASTER-Tunka | (10h 52m 29.60s , +61d 59m 02.1s) | P- | 20 | 13.8 | 134 | 2025-11-08 12:59:00 | MASTER- | (10h 51m 53.20s , +62d 04m 19.3s) | C | 20 | 17.4 | 162 | 2025-11-08 12:59:24 | MASTER-Tunka | (10h 52m 29.47s , +61d 59m 03.0s) | P- | 30 | 13.8 | 162 | 2025-11-08 12:59:24 | MASTER- | (10h 51m 53.19s , +62d 04m 19.8s) | C | 30 | 17.6 | 201 | 2025-11-08 12:59:57 | MASTER-Tunka | (10h 52m 29.45s , +61d 59m 03.8s) | P- | 40 | 14.1 | 201 | 2025-11-08 12:59:57 | MASTER- | (10h 51m 53.15s , +62d 04m 20.3s) | C | 40 | 17.7 | 245 | 2025-11-08 13:00:42 | MASTER-Tunka | (10h 52m 29.33s , +61d 59m 05.0s) | P- | 40 | 13.8 | 245 | 2025-11-08 13:00:42 | MASTER- | (10h 51m 53.04s , +62d 04m 21.0s) | C | 40 | 17.5 | 293 | 2025-11-08 13:01:25 | MASTER-Tunka | (10h 52m 29.39s , +61d 59m 06.3s) | P- | 50 | 14.0 | 293 | 2025-11-08 13:01:25 | MASTER- | (10h 51m 53.02s , +62d 04m 22.7s) | C | 50 | 18.0 | 352 | 2025-11-08 13:02:18 | MASTER-Tunka | (10h 52m 29.17s , +61d 59m 07.7s) | P- | 60 | 14.1 | 352 | 2025-11-08 13:02:18 | MASTER- | (10h 51m 52.87s , +62d 04m 24.3s) | C | 60 | 17.7 | 416 | 2025-11-08 13:03:22 | MASTER-Tunka | (10h 52m 29.04s , +61d 59m 09.2s) | P- | 60 | 14.1 | 416 | 2025-11-08 13:03:22 | MASTER- | (10h 51m 52.69s , +62d 04m 26.3s) | C | 60 | 17.8 | 479 | 2025-11-08 13:04:26 | MASTER-Tunka | (10h 52m 28.87s , +61d 59m 10.6s) | P- | 60 | 14.1 | 479 | 2025-11-08 13:04:26 | MASTER- | (10h 51m 52.49s , +62d 04m 27.9s) | C | 60 | 17.8 | 543 | 2025-11-08 13:05:29 | MASTER-Tunka | (10h 52m 28.81s , +61d 59m 12.1s) | P- | 60 | 14.0 | 543 | 2025-11-08 13:05:30 | MASTER- | (10h 51m 52.28s , +62d 04m 29.4s) | C | 60 | 17.7 | 606 | 2025-11-08 13:06:33 | MASTER-Tunka | (10h 52m 28.72s , +61d 59m 13.7s) | P- | 60 | 14.0 | 606 | 2025-11-08 13:06:33 | MASTER- | (10h 51m 52.11s , +62d 04m 31.4s) | C | 60 | 17.6 | 670 | 2025-11-08 13:07:37 | MASTER-Tunka | (10h 52m 28.53s , +61d 59m 15.6s) | P- | 60 | 14.1 | 670 | 2025-11-08 13:07:37 | MASTER- | (10h 51m 51.90s , +62d 04m 32.7s) | C | 60 | 17.7 | 733 | 2025-11-08 13:08:40 | MASTER-Tunka | (10h 52m 28.39s , +61d 59m 18.2s) | P- | 60 | 14.0 | 733 | 2025-11-08 13:08:40 | MASTER- | (10h 51m 51.73s , +62d 04m 35.2s) | C | 60 | 17.7 | 797 | 2025-11-08 13:09:43 | MASTER-Tunka | (10h 52m 28.30s , +61d 59m 20.7s) | P- | 60 | 14.0 | 797 | 2025-11-08 13:09:43 | MASTER- | (10h 51m 51.55s , +62d 04m 37.6s) | C | 60 | 17.7 | 860 | 2025-11-08 13:10:46 | MASTER-Tunka | (10h 52m 28.10s , +61d 59m 22.2s) | P- | 60 | 13.9 | 860 | 2025-11-08 13:10:46 | MASTER- | (10h 51m 51.36s , +62d 04m 39.4s) | C | 60 | 17.6 | 924 | 2025-11-08 13:11:50 | MASTER-Tunka | (10h 52m 28.06s , +61d 59m 24.0s) | P- | 60 | 13.8 | 924 | 2025-11-08 13:11:50 | MASTER- | (10h 51m 51.13s , +62d 04m 41.3s) | C | 60 | 17.6 | 987 | 2025-11-08 13:12:53 | MASTER-Tunka | (10h 52m 27.80s , +61d 59m 25.9s) | P- | 60 | 13.9 | 987 | 2025-11-08 13:12:53 | MASTER- | (10h 51m 50.91s , +62d 04m 43.6s) | C | 60 | 17.7 | 1050 | 2025-11-08 13:13:57 | MASTER-Tunka | (10h 52m 27.59s , +61d 59m 28.2s) | P- | 60 | 14.0 | 1050 | 2025-11-08 13:13:57 | MASTER- | (10h 51m 50.72s , +62d 04m 45.4s) | C | 60 | 17.7 | 1114 | 2025-11-08 13:15:00 | MASTER-Tunka | (10h 52m 27.52s , +61d 59m 30.2s) | P- | 60 | 13.7 | 1114 | 2025-11-08 13:15:01 | MASTER- | (10h 51m 50.53s , +62d 04m 47.7s) | C | 60 | 17.7 | 1177 | 2025-11-08 13:16:04 | MASTER-Tunka | (10h 52m 27.42s , +61d 59m 31.9s) | P- | 60 | 13.5 | 1177 | 2025-11-08 13:16:04 | MASTER- | (10h 51m 50.36s , +62d 04m 49.5s) | C | 60 | 17.7 | 1241 | 2025-11-08 13:17:07 | MASTER-Tunka | (10h 52m 27.22s , +61d 59m 33.3s) | P- | 60 | 14.0 | 1241 | 2025-11-08 13:17:07 | MASTER- | (10h 51m 50.27s , +62d 04m 50.8s) | C | 60 | 17.6 | 1304 | 2025-11-08 13:18:11 | MASTER-Tunka | (10h 52m 27.00s , +61d 59m 34.6s) | P- | 60 | 14.0 | 1304 | 2025-11-08 13:18:11 | MASTER- | (10h 51m 50.06s , +62d 04m 52.4s) | C | 60 | 17.6 | 1368 | 2025-11-08 13:19:14 | MASTER-Tunka | (10h 52m 26.80s , +61d 59m 36.0s) | P- | 60 | 14.0 | 1368 | 2025-11-08 13:19:14 | MASTER- | (10h 51m 49.88s , +62d 04m 54.2s) | C | 60 | 17.6 | 1431 | 2025-11-08 13:20:18 | MASTER-Tunka | (10h 52m 26.66s , +61d 59m 37.8s) | P- | 60 | 14.0 | 1431 | 2025-11-08 13:20:18 | MASTER- | (10h 51m 49.72s , +62d 04m 56.1s) | C | 60 | 17.7 | 1495 | 2025-11-08 13:21:21 | MASTER-Tunka | (10h 52m 26.53s , +61d 59m 40.5s) | P- | 60 | 14.0 | 1495 | 2025-11-08 13:21:22 | MASTER- | (10h 51m 49.55s , +62d 04m 57.7s) | C | 60 | 17.6 | 1559 | 2025-11-08 13:22:25 | MASTER-Tunka | (10h 52m 26.30s , +61d 59m 41.9s) | P- | 60 | 14.0 | 1559 | 2025-11-08 13:22:25 | MASTER- | (10h 51m 49.37s , +62d 04m 59.7s) | C | 60 | 17.6 | 1622 | 2025-11-08 13:23:28 | MASTER-Tunka | (10h 52m 25.91s , +61d 59m 40.4s) | P- | 60 | 14.4 | 1622 | 2025-11-08 13:23:28 | MASTER- | (10h 51m 49.17s , +62d 05m 01.6s) | C | 60 | 17.5 | 1685 | 2025-11-08 13:24:32 | MASTER-Tunka | (10h 52m 26.42s , +61d 59m 43.8s) | P- | 60 | 14.3 | 1685 | 2025-11-08 13:24:32 | MASTER- | (10h 51m 48.97s , +62d 05m 03.7s) | C | 60 | 17.5 | 1749 | 2025-11-08 13:25:35 | MASTER-Tunka | (10h 52m 25.94s , +61d 59m 48.0s) | P- | 60 | 13.3 | 1749 | 2025-11-08 13:25:35 | MASTER- | (10h 51m 48.81s , +62d 05m 05.5s) | C | 60 | 17.6 | 1812 | 2025-11-08 13:26:39 | MASTER-Tunka | (10h 52m 25.57s , +61d 59m 48.7s) | P- | 60 | 13.8 | 1812 | 2025-11-08 13:26:39 | MASTER- | (10h 51m 48.58s , +62d 05m 07.2s) | C | 60 | 17.5 | 1876 | 2025-11-08 13:27:42 | MASTER-Tunka | (10h 52m 25.27s , +61d 59m 47.8s) | P- | 60 | 14.5 | 1876 | 2025-11-08 13:27:42 | MASTER- | (10h 51m 48.42s , +62d 05m 09.3s) | C | 60 | 17.6 | 1939 | 2025-11-08 13:28:45 | MASTER- | (10h 51m 48.26s , +62d 05m 11.4s) | C | 60 | 17.7 | 2003 | 2025-11-08 13:29:49 | MASTER-Tunka | (10h 52m 25.20s , +61d 59m 52.2s) | P- | 60 | 14.4 | 2003 | 2025-11-08 13:29:49 | MASTER- | (10h 51m 48.10s , +62d 05m 13.2s) | C | 60 | 17.6 | 2066 | 2025-11-08 13:30:53 | MASTER-Tunka | (10h 52m 25.03s , +61d 59m 53.5s) | P- | 60 | 14.4 | 2066 | 2025-11-08 13:30:53 | MASTER- | (10h 51m 47.91s , +62d 05m 15.6s) | C | 60 | 17.7 | 2129 | 2025-11-08 13:31:56 | MASTER-Tunka | (10h 52m 24.92s , +61d 59m 55.3s) | P- | 60 | 14.6 | 2129 | 2025-11-08 13:31:56 | MASTER- | (10h 51m 47.74s , +62d 05m 17.5s) | C | 60 | 17.8 | 2193 | 2025-11-08 13:32:59 | MASTER-Tunka | (10h 52m 24.62s , +61d 59m 58.2s) | P- | 60 | 14.6 | 2193 | 2025-11-08 13:32:59 | MASTER- | (10h 51m 47.50s , +62d 05m 19.7s) | C | 60 | 17.6 | 2256 | 2025-11-08 13:34:03 | MASTER-Tunka | (10h 52m 24.02s , +62d 00m 01.1s) | P- | 60 | 14.4 | 2256 | 2025-11-08 13:34:03 | MASTER- | (10h 51m 47.34s , +62d 05m 21.5s) | C | 60 | 17.7 | 2320 | 2025-11-08 13:35:06 | MASTER-Tunka | (10h 52m 24.16s , +62d 00m 04.2s) | P- | 60 | 14.0 | 2320 | 2025-11-08 13:35:06 | MASTER- | (10h 51m 47.12s , +62d 05m 22.9s) | C | 60 | 17.5 | 2383 | 2025-11-08 13:36:10 | MASTER-Tunka | (10h 52m 23.83s , +62d 00m 02.5s) | P- | 60 | 14.5 | 2383 | 2025-11-08 13:36:10 | MASTER- | (10h 51m 46.92s , +62d 05m 24.8s) | C | 60 | 17.7 | 2447 | 2025-11-08 13:37:13 | MASTER-Tunka | (10h 52m 23.41s , +62d 00m 06.4s) | P- | 60 | 14.4 | 2447 | 2025-11-08 13:37:13 | MASTER- | (10h 51m 46.70s , +62d 05m 26.9s) | C | 60 | 17.5 | 2510 | 2025-11-08 13:38:16 | MASTER-Tunka | (10h 52m 23.82s , +62d 00m 07.0s) | P- | 60 | 14.4 | 2510 | 2025-11-08 13:38:16 | MASTER- | (10h 51m 46.49s , +62d 05m 28.5s) | C | 60 | 17.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42622. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40684] GRB 251102B: SVOM/GRM observation
by GCN Circulars 08 Nov '25

08 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42621 SUBJECT: GRB 251102B: SVOM/GRM observation DATE: 25/11/08 13:30:33 GMT FROM: yzh807926(a)163.com SVOM/GRM team: Zheng-Hang Yu, Chen-Wei Wang, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Sebastien Guillot (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered on-ground by a burst GRB 251102B at 2025-11-02T21:15:53.000 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #42533). 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 peak with a T90 of 3.5 +1.5/-1.0 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251102B.png In addition, the position of this burst, as determined by Fermi/GBM (RA= 110.6, DEC= -69.7, GCN#42533), is located at about 83 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0-6 to T0+4 s is best fitted by a power law function. The power law index is -1.98 +0.01/-0.03. The event fluence (10-1000 keV) in this time interval is (1.25 +0.16/-0.15)E-6 erg/cm^2. 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 point of contact for this burst is: Zheng-Hang Yu(IHEP)(zhyu(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/42621. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40683] Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB
by GCN Circulars 08 Nov '25

08 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42620 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB DATE: 25/11/08 12:01:17 GMT FROM: A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca(a)unitn.it> A. Holzmann Airasca (UniTrento and INFN Bari) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 784279167/251108305 at 07:19:22.22 UT on 08 November 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to local particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/42620. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40682] LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
by GCN Circulars 08 Nov '25

08 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42619 SUBJECT: LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate DATE: 25/11/08 11:42:05 GMT FROM: FRANCESCO STOLZI at Unisi <stolzi3(a)unisi.it> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S251108dn during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2025-11-08 10:32:43.578 UTC (GPS time: 1446633181.578). The candidate was found by the Aframe [1], cWB BBH [2], GstLAL [3], MBTA [4], PyCBC Live [5], and SPIIR [6] analysis pipelines. S251108dn is an event of interest because its false alarm rate, as estimated by the online analysis, is 9.4e-18 Hz, or about one in 1e10 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S251108dn The classification of the GW signal, in order of descending probability, is BBH (>99%), NSBH (<1%), Terrestrial (<1%), or BNS (<1%). Noise transients (glitches) were present in the LIGO Livingston and Virgo detector data within two seconds of the event time, which may affect the parameters or the significance of the candidate. 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%. [7] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [7] 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 2%. The source chirp mass falls with highest probability in the bin (5.5, 11.0) 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 [8], distributed via GCN and SCiMMA notices about 26 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [8], 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 697 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1165 +/- 309 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] T. Mishra et al. PRD 105, 083018 (2022) doi:10.1103/PhysRevD.105.083018 [3] 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 [4] Alléné et al. CQG 42, 105009 (2025) doi:10.1088/1361-6382/add234 [5] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [6] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023 [7] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [8] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/42619. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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