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

[vsnet-grb-info 40204] GRB 251005C: SVOM/GRM observation of a likely short GRB
by GCN Circulars 07 Oct '25

07 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42135 SUBJECT: GRB 251005C: SVOM/GRM observation of a likely short GRB DATE: 25/10/07 03:12:49 GMT FROM: Xinghao Luo at SVOM/GRN <2952704891(a)qq.com> SVOM/GRM team: Xing-Hao Luo, Chen-Wei Wang, Zheng-Hang Yu, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Frédéric Daigne (IAP), Stéphane Schanne (CEA) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a burst GRB 251005C(SVOM trigger reference: sb25100502) at 2025-10-05T16:06:54.000 UTC(T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN#42118) and Swift/BAT (K. L. Page et al., GCN#42113) With the event_by_event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multi-pulses with a T90 of 1.6 +0.6/-0.3 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251005C.png In addition, the position of this burst, as determined by Swift/XRT (RA=75.673 , DEC=16.882, GCN#42116), is located at about 51 degrees form the SVOM optical axis, which is outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0-0.4 to T0+1.6 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -0.81 +0.16/-0.14 and the cutoff energy, parameterized as Epeak, is 900 +547/-285 keV. The event fluence (10-1000 keV) in this time interval is (2.17 +0.19/-0.18)E-06 erg/cm^2. The localization of GRB 251005C in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb251005C_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 point of contact for this burst is: Xing-Hao Luo (2952704891(a)qq.com) View this GCN Circular online at https://gcn.nasa.gov/circulars/42135. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40203] LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
by GCN Circulars 07 Oct '25

07 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42134 SUBJECT: LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate DATE: 25/10/07 00:10:26 GMT FROM: yamazaki.ryo.77(a)gmail.com The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S251006dd during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2025-10-06 23:37:17.979 UTC (GPS time: 1443829055.979). The candidate was found by the Aframe [1], MBTA [2], PyCBC Live [3], and SPIIR [4] analysis pipelines. S251006dd is an event of interest because its false alarm rate, as estimated by the online analysis, is 5.4e-16 Hz, or about one in 1e8 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S251006dd The classification of the GW signal, in order of descending probability, is BBH (>99%), NSBH (<1%), Terrestrial (<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%. [5] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [5] 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 14%. 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,1, an initial localization generated by BAYESTAR [6], distributed via GCN and SCiMMA notices about 26 seconds after the candidate event time. * bayestar.multiorder.fits,2, an initial localization generated by BAYESTAR [6], 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,2. For the bayestar.multiorder.fits,2 sky map, the 90% credible region is 109 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 706 +/- 151 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] Alléné et al. CQG 42, 105009 (2025) doi:10.1088/1361-6382/add234 [3] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [4] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023 [5] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [6] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/42134. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40202] Fermi GRB 251006B: Global MASTER-Net observations report
by GCN Circulars 06 Oct '25

06 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42133 SUBJECT: Fermi GRB 251006B: Global MASTER-Net observations report DATE: 25/10/06 21:16:05 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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 251006B ( Fermi GBM team, GCN 42131) errorbox 532 sec after notice time and 575 sec after trigger time at 2025-10-06 20:14:39 UT, with upper limit up to 18.4 mag. The observations began at zenith distance = 63 deg. The sun altitude is -41.2 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 251006B errorbox 545 sec after notice time and 587 sec after trigger time at 2025-10-06 20:14:51 UT, with upper limit up to 14.9 mag. The observations began at zenith distance = 59 deg. The sun altitude is -51.1 deg. MASTER-Tunka robotic telescope located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB 251006B errorbox 563 sec after notice time and 606 sec after trigger time at 2025-10-06 20:15:10 UT, with upper limit up to 16.7 mag. The observations began at zenith distance = 58 deg. The sun altitude is -28.3 deg. The galactic latitude b = -54 deg., longitude l = 177 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3008721 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 605 | 2025-10-06 20:14:39 | MASTER-SAAO | (02h 39m 49.30s , -04d 20m 36.1s) | C | 60 | 17.6 | 665 | 2025-10-06 20:14:39 | MASTER-SAAO | (02h 39m 49.30s , -04d 20m 36.1s) | C | 180 | 18.4 | Coadd 605 | 2025-10-06 20:14:39 | MASTER-SAAO | (02h 37m 57.07s , -04d 05m 19.3s) | C | 60 | 17.5 | 665 | 2025-10-06 20:14:39 | MASTER-SAAO | (02h 37m 57.07s , -04d 05m 19.3s) | C | 180 | 18.2 | Coadd 648 | 2025-10-06 20:14:51 | MASTER-Kislovodsk | (02h 39m 53.89s , -04d 03m 53.7s) | P| | 120 | 13.3 | 648 | 2025-10-06 20:14:51 | MASTER-Kislovodsk | (02h 39m 44.13s , -03d 40m 31.4s) | P- | 120 | 14.9 | 609 | 2025-10-06 20:15:10 | MASTER-Tunka | (02h 42m 02.24s , -03d 51m 31.9s) | C | 5 | 16.2 | 614 | 2025-10-06 20:15:10 | MASTER-Tunka | (02h 42m 02.24s , -03d 51m 31.9s) | C | 15 | 16.7 | Coadd 609 | 2025-10-06 20:15:10 | MASTER- | (02h 41m 39.21s , -03d 46m 29.9s) | C | 5 | 15.9 | 618 | 2025-10-06 20:15:18 | MASTER- | (02h 41m 39.20s , -03d 46m 30.4s) | C | 5 | 15.8 | 618 | 2025-10-06 20:15:18 | MASTER-Tunka | (02h 42m 02.24s , -03d 51m 32.3s) | C | 5 | 16.1 | 627 | 2025-10-06 20:15:27 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 32.7s) | C | 5 | 16.1 | 627 | 2025-10-06 20:15:28 | MASTER- | (02h 41m 39.22s , -03d 46m 30.9s) | C | 5 | 15.9 | 639 | 2025-10-06 20:15:40 | MASTER-Tunka | (02h 42m 02.25s , -03d 51m 33.0s) | C | 5 | 16.1 | 644 | 2025-10-06 20:15:40 | MASTER-Tunka | (02h 42m 02.25s , -03d 51m 32.9s) | C | 15 | 16.6 | Coadd 639 | 2025-10-06 20:15:40 | MASTER- | (02h 41m 39.21s , -03d 46m 31.1s) | C | 5 | 15.9 | 652 | 2025-10-06 20:15:52 | MASTER-Tunka | (02h 42m 02.24s , -03d 51m 33.2s) | C | 5 | 16.0 | 652 | 2025-10-06 20:15:52 | MASTER- | (02h 41m 39.21s , -03d 46m 31.6s) | C | 5 | 15.8 | 684 | 2025-10-06 20:15:58 | MASTER-SAAO | (02h 39m 49.23s , -04d 20m 36.1s) | C | 60 | 17.6 | 684 | 2025-10-06 20:15:58 | MASTER-SAAO | (02h 37m 56.96s , -04d 05m 19.4s) | C | 60 | 17.6 | 661 | 2025-10-06 20:16:01 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 33.4s) | C | 5 | 16.0 | 661 | 2025-10-06 20:16:01 | MASTER- | (02h 41m 39.22s , -03d 46m 31.7s) | C | 5 | 15.9 | 669 | 2025-10-06 20:16:10 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 33.8s) | C | 5 | 16.0 | 674 | 2025-10-06 20:16:10 | MASTER-Tunka | (02h 42m 02.27s , -03d 51m 33.8s) | C | 15 | 16.6 | Coadd 669 | 2025-10-06 20:16:10 | MASTER- | (02h 41m 39.22s , -03d 46m 32.1s) | C | 5 | 15.8 | 678 | 2025-10-06 20:16:18 | MASTER-Tunka | (02h 42m 02.27s , -03d 51m 34.2s) | C | 5 | 16.1 | 678 | 2025-10-06 20:16:18 | MASTER- | (02h 41m 39.22s , -03d 46m 32.5s) | C | 5 | 15.8 | 686 | 2025-10-06 20:16:27 | MASTER-Tunka | (02h 42m 02.27s , -03d 51m 34.3s) | C | 5 | 16.0 | 686 | 2025-10-06 20:16:27 | MASTER- | (02h 41m 39.23s , -03d 46m 32.7s) | C | 5 | 15.9 | 715 | 2025-10-06 20:16:55 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 35.5s) | C | 5 | 16.1 | 720 | 2025-10-06 20:16:55 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 35.4s) | C | 15 | 16.5 | Coadd 715 | 2025-10-06 20:16:55 | MASTER- | (02h 41m 39.23s , -03d 46m 33.7s) | C | 5 | 15.9 | 723 | 2025-10-06 20:17:03 | MASTER-Tunka | (02h 42m 02.25s , -03d 51m 35.7s) | C | 5 | 16.0 | 723 | 2025-10-06 20:17:03 | MASTER- | (02h 41m 39.22s , -03d 46m 34.0s) | C | 5 | 15.9 | 787 | 2025-10-06 20:17:11 | MASTER-Kislovodsk | (02h 39m 44.20s , -03d 40m 29.1s) | P- | 120 | 14.3 | 787 | 2025-10-06 20:17:11 | MASTER-Kislovodsk | (02h 39m 55.26s , -04d 03m 41.8s) | P| | 120 | 13.6 | 732 | 2025-10-06 20:17:12 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 35.8s) | C | 5 | 16.1 | 732 | 2025-10-06 20:17:13 | MASTER- | (02h 41m 39.22s , -03d 46m 34.3s) | C | 5 | 15.9 | 763 | 2025-10-06 20:17:17 | MASTER-SAAO | (02h 39m 49.17s , -04d 20m 36.1s) | C | 60 | 17.6 | 763 | 2025-10-06 20:17:17 | MASTER-SAAO | (02h 37m 56.87s , -04d 05m 19.6s) | C | 60 | 17.4 | 740 | 2025-10-06 20:17:21 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 36.1s) | C | 5 | 16.0 | 745 | 2025-10-06 20:17:21 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 36.1s) | C | 15 | 16.6 | Coadd 740 | 2025-10-06 20:17:21 | MASTER- | (02h 41m 39.22s , -03d 46m 34.5s) | C | 5 | 15.8 | 749 | 2025-10-06 20:17:29 | MASTER-Tunka | (02h 42m 02.25s , -03d 51m 36.3s) | C | 5 | 16.1 | 749 | 2025-10-06 20:17:29 | MASTER- | (02h 41m 39.21s , -03d 46m 34.8s) | C | 5 | 15.8 | 757 | 2025-10-06 20:17:38 | MASTER-Tunka | (02h 42m 02.25s , -03d 51m 36.4s) | C | 5 | 16.1 | 757 | 2025-10-06 20:17:38 | MASTER- | (02h 41m 39.21s , -03d 46m 35.1s) | C | 5 | 15.8 | 766 | 2025-10-06 20:17:46 | MASTER-Tunka | (02h 42m 02.25s , -03d 51m 36.9s) | C | 5 | 16.0 | 771 | 2025-10-06 20:17:46 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 36.9s) | C | 15 | 16.7 | Coadd 766 | 2025-10-06 20:17:46 | MASTER- | (02h 41m 39.21s , -03d 46m 35.4s) | C | 5 | 15.8 | 774 | 2025-10-06 20:17:54 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 37.2s) | C | 5 | 16.1 | 774 | 2025-10-06 20:17:54 | MASTER- | (02h 41m 39.21s , -03d 46m 35.7s) | C | 5 | 15.9 | 782 | 2025-10-06 20:18:03 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 37.2s) | C | 5 | 16.1 | 782 | 2025-10-06 20:18:03 | MASTER- | (02h 41m 39.21s , -03d 46m 36.0s) | C | 5 | 15.9 | 814 | 2025-10-06 20:18:35 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 38.1s) | C | 5 | 16.1 | 819 | 2025-10-06 20:18:35 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 38.2s) | C | 15 | 16.7 | Coadd 814 | 2025-10-06 20:18:35 | MASTER- | (02h 41m 39.20s , -03d 46m 37.1s) | C | 5 | 16.0 | 842 | 2025-10-06 20:18:36 | MASTER-SAAO | (02h 39m 49.10s , -04d 20m 36.0s) | C | 60 | 17.6 | 842 | 2025-10-06 20:18:36 | MASTER-SAAO | (02h 37m 56.77s , -04d 05m 19.7s) | C | 60 | 17.6 | 838 | 2025-10-06 20:18:59 | MASTER-Tunka | (02h 42m 02.27s , -03d 51m 38.9s) | C | 5 | 16.0 | 838 | 2025-10-06 20:18:59 | MASTER- | (02h 41m 39.22s , -03d 46m 38.0s) | C | 5 | 15.9 | 847 | 2025-10-06 20:19:07 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 39.2s) | C | 5 | 16.0 | 847 | 2025-10-06 20:19:07 | MASTER- | (02h 41m 39.20s , -03d 46m 38.2s) | C | 5 | 15.9 | 856 | 2025-10-06 20:19:17 | MASTER-Tunka | (02h 42m 02.27s , -03d 51m 39.5s) | C | 5 | 16.1 | 861 | 2025-10-06 20:19:17 | MASTER-Tunka | (02h 42m 02.27s , -03d 51m 39.5s) | C | 15 | 16.5 | Coadd 856 | 2025-10-06 20:19:17 | MASTER- | (02h 41m 39.22s , -03d 46m 38.6s) | C | 5 | 15.9 | 865 | 2025-10-06 20:19:25 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 39.7s) | C | 5 | 16.2 | 865 | 2025-10-06 20:19:25 | MASTER- | (02h 41m 39.21s , -03d 46m 38.8s) | C | 5 | 15.9 | 927 | 2025-10-06 20:19:31 | MASTER-Kislovodsk | (02h 39m 55.35s , -04d 03m 40.8s) | P| | 120 | 13.6 | 927 | 2025-10-06 20:19:31 | MASTER-Kislovodsk | (02h 39m 44.35s , -03d 40m 26.8s) | P- | 120 | 14.5 | 874 | 2025-10-06 20:19:34 | MASTER- | (02h 41m 39.21s , -03d 46m 39.1s) | C | 5 | 16.0 | 874 | 2025-10-06 20:19:34 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 40.0s) | C | 5 | 16.2 | 883 | 2025-10-06 20:19:43 | MASTER- | (02h 41m 39.21s , -03d 46m 39.1s) | C | 5 | 16.0 | 883 | 2025-10-06 20:19:43 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 40.1s) | C | 5 | 16.1 | 888 | 2025-10-06 20:19:43 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 40.1s) | C | 15 | 16.7 | Coadd 892 | 2025-10-06 20:19:52 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 40.3s) | C | 5 | 16.1 | 892 | 2025-10-06 20:19:52 | MASTER- | (02h 41m 39.21s , -03d 46m 39.4s) | C | 5 | 16.0 | 900 | 2025-10-06 20:20:01 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 40.5s) | C | 5 | 16.1 | 900 | 2025-10-06 20:20:01 | MASTER- | (02h 41m 39.22s , -03d 46m 39.8s) | C | 5 | 15.9 | 928 | 2025-10-06 20:20:29 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 41.5s) | C | 5 | 16.2 | 933 | 2025-10-06 20:20:29 | MASTER-Tunka | (02h 42m 02.25s , -03d 51m 41.5s) | C | 15 | 16.7 | Coadd 928 | 2025-10-06 20:20:29 | MASTER- | (02h 41m 39.20s , -03d 46m 40.5s) | C | 5 | 15.9 | 936 | 2025-10-06 20:20:37 | MASTER-Tunka | (02h 42m 02.24s , -03d 51m 41.8s) | C | 5 | 16.2 | 937 | 2025-10-06 20:20:37 | MASTER- | (02h 41m 39.20s , -03d 46m 40.8s) | C | 5 | 15.9 | 946 | 2025-10-06 20:20:47 | MASTER-Tunka | (02h 42m 02.25s , -03d 51m 42.0s) | C | 5 | 16.2 | 946 | 2025-10-06 20:20:47 | MASTER- | (02h 41m 39.22s , -03d 46m 41.0s) | C | 5 | 16.0 | 956 | 2025-10-06 20:20:57 | MASTER-Tunka | (02h 42m 02.25s , -03d 51m 42.3s) | C | 5 | 16.1 | 961 | 2025-10-06 20:20:57 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 42.3s) | C | 15 | 16.7 | Coadd 956 | 2025-10-06 20:20:57 | MASTER- | (02h 41m 39.21s , -03d 46m 41.3s) | C | 5 | 16.0 | 965 | 2025-10-06 20:21:05 | MASTER- | (02h 41m 39.22s , -03d 46m 41.6s) | C | 5 | 16.0 | 965 | 2025-10-06 20:21:05 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 42.5s) | C | 5 | 16.1 | 973 | 2025-10-06 20:21:14 | MASTER-Tunka | (02h 42m 02.28s , -03d 51m 42.6s) | C | 5 | 16.1 | 973 | 2025-10-06 20:21:14 | MASTER- | (02h 41m 39.23s , -03d 46m 41.8s) | C | 5 | 16.0 | 982 | 2025-10-06 20:21:22 | MASTER-Tunka | (02h 42m 02.28s , -03d 51m 42.9s) | C | 5 | 16.1 | 987 | 2025-10-06 20:21:22 | MASTER-Tunka | (02h 42m 02.28s , -03d 51m 43.0s) | C | 15 | 16.7 | Coadd 982 | 2025-10-06 20:21:22 | MASTER- | (02h 41m 39.23s , -03d 46m 41.9s) | C | 5 | 16.0 | 990 | 2025-10-06 20:21:31 | MASTER- | (02h 41m 39.23s , -03d 46m 42.3s) | C | 5 | 15.9 | 990 | 2025-10-06 20:21:31 | MASTER-Tunka | (02h 42m 02.27s , -03d 51m 43.2s) | C | 5 | 16.1 | 999 | 2025-10-06 20:21:40 | MASTER-Tunka | (02h 42m 02.27s , -03d 51m 43.6s) | C | 5 | 16.1 | 999 | 2025-10-06 20:21:40 | MASTER- | (02h 41m 39.23s , -03d 46m 42.6s) | C | 5 | 15.9 | 1008 | 2025-10-06 20:21:48 | MASTER-Tunka | (02h 42m 02.27s , -03d 51m 43.8s) | C | 5 | 16.1 | 1013 | 2025-10-06 20:21:48 | MASTER-Tunka | (02h 42m 02.28s , -03d 51m 43.8s) | C | 15 | 16.7 | Coadd 1008 | 2025-10-06 20:21:48 | MASTER- | (02h 41m 39.23s , -03d 46m 42.9s) | C | 5 | 16.0 | 1067 | 2025-10-06 20:21:50 | MASTER-Kislovodsk | (02h 39m 44.50s , -03d 40m 23.0s) | P- | 120 | 14.3 | 1067 | 2025-10-06 20:21:51 | MASTER-Kislovodsk | (02h 39m 55.40s , -04d 03m 37.6s) | P| | 120 | 13.7 | 1016 | 2025-10-06 20:21:57 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 44.0s) | C | 5 | 16.2 | 1016 | 2025-10-06 20:21:57 | MASTER- | (02h 41m 39.22s , -03d 46m 43.0s) | C | 5 | 16.0 | 1024 | 2025-10-06 20:22:05 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 44.3s) | C | 5 | 16.1 | 1024 | 2025-10-06 20:22:05 | MASTER- | (02h 41m 39.21s , -03d 46m 43.1s) | C | 5 | 16.0 | 1033 | 2025-10-06 20:22:14 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 44.6s) | C | 5 | 16.1 | 1038 | 2025-10-06 20:22:14 | MASTER-Tunka | (02h 42m 02.27s , -03d 51m 44.5s) | C | 15 | 16.6 | Coadd 1033 | 2025-10-06 20:22:14 | MASTER- | (02h 41m 39.21s , -03d 46m 43.8s) | C | 5 | 16.0 | 1042 | 2025-10-06 20:22:22 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 44.7s) | C | 5 | 16.0 | 1042 | 2025-10-06 20:22:22 | MASTER- | (02h 41m 39.20s , -03d 46m 43.9s) | C | 5 | 16.0 | 1050 | 2025-10-06 20:22:31 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 44.9s) | C | 5 | 16.1 | 1050 | 2025-10-06 20:22:31 | MASTER- | (02h 41m 39.20s , -03d 46m 44.3s) | C | 5 | 15.9 | 1059 | 2025-10-06 20:22:39 | MASTER- | (02h 41m 39.20s , -03d 46m 44.5s) | C | 5 | 16.0 | 1059 | 2025-10-06 20:22:39 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 45.1s) | C | 5 | 16.1 | 1064 | 2025-10-06 20:22:39 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 45.2s) | C | 15 | 16.6 | Coadd 1067 | 2025-10-06 20:22:48 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 45.5s) | C | 5 | 16.1 | 1068 | 2025-10-06 20:22:48 | MASTER- | (02h 41m 39.19s , -03d 46m 44.8s) | C | 5 | 15.9 | 1076 | 2025-10-06 20:22:57 | MASTER- | (02h 41m 39.18s , -03d 46m 45.2s) | C | 5 | 15.9 | 1076 | 2025-10-06 20:22:57 | MASTER-Tunka | (02h 42m 02.25s , -03d 51m 45.6s) | C | 5 | 16.1 | 1085 | 2025-10-06 20:23:06 | MASTER-Tunka | (02h 42m 02.27s , -03d 51m 45.8s) | C | 5 | 16.1 | 1090 | 2025-10-06 20:23:06 | MASTER-Tunka | (02h 42m 02.27s , -03d 51m 45.8s) | C | 15 | 16.6 | Coadd 1085 | 2025-10-06 20:23:06 | MASTER- | (02h 41m 39.20s , -03d 46m 45.4s) | C | 5 | 15.9 | 1094 | 2025-10-06 20:23:14 | MASTER- | (02h 41m 39.19s , -03d 46m 45.8s) | C | 5 | 15.9 | 1094 | 2025-10-06 20:23:14 | MASTER-Tunka | (02h 42m 02.27s , -03d 51m 46.2s) | C | 5 | 16.0 | 1102 | 2025-10-06 20:23:23 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 46.5s) | C | 5 | 16.1 | 1102 | 2025-10-06 20:23:23 | MASTER- | (02h 41m 39.18s , -03d 46m 46.1s) | C | 5 | 15.9 | 1111 | 2025-10-06 20:23:31 | MASTER-Tunka | (02h 42m 02.25s , -03d 51m 46.6s) | C | 5 | 16.1 | 1116 | 2025-10-06 20:23:31 | MASTER-Tunka | (02h 42m 02.25s , -03d 51m 46.6s) | C | 15 | 16.6 | Coadd 1111 | 2025-10-06 20:23:31 | MASTER- | (02h 41m 39.18s , -03d 46m 46.1s) | C | 5 | 16.0 | 1119 | 2025-10-06 20:23:40 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 46.7s) | C | 5 | 16.1 | 1120 | 2025-10-06 20:23:40 | MASTER- | (02h 41m 39.19s , -03d 46m 46.4s) | C | 5 | 15.9 | 1128 | 2025-10-06 20:23:48 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 46.9s) | C | 5 | 16.1 | 1128 | 2025-10-06 20:23:48 | MASTER- | (02h 41m 39.19s , -03d 46m 46.6s) | C | 5 | 15.9 | 1136 | 2025-10-06 20:23:57 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 47.1s) | C | 5 | 16.1 | 1141 | 2025-10-06 20:23:57 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 47.1s) | C | 15 | 16.6 | Coadd 1136 | 2025-10-06 20:23:57 | MASTER- | (02h 41m 39.18s , -03d 46m 46.7s) | C | 5 | 15.9 | 1145 | 2025-10-06 20:24:05 | MASTER-Tunka | (02h 42m 02.25s , -03d 51m 47.4s) | C | 5 | 16.1 | 1145 | 2025-10-06 20:24:05 | MASTER- | (02h 41m 39.18s , -03d 46m 46.9s) | C | 5 | 16.0 | 1207 | 2025-10-06 20:24:10 | MASTER-Kislovodsk | (02h 39m 44.60s , -03d 40m 18.3s) | P- | 120 | 14.3 | 1207 | 2025-10-06 20:24:10 | MASTER-Kislovodsk | (02h 39m 55.41s , -04d 03m 34.1s) | P| | 120 | 13.7 | 1160 | 2025-10-06 20:24:20 | MASTER- | (02h 41m 39.19s , -03d 46m 47.2s) | C | 5 | 15.9 | 1160 | 2025-10-06 20:24:20 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 47.7s) | C | 5 | 16.1 | 1168 | 2025-10-06 20:24:29 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 47.9s) | C | 5 | 16.1 | 1168 | 2025-10-06 20:24:29 | MASTER- | (02h 41m 39.19s , -03d 46m 47.4s) | C | 5 | 15.9 | 1177 | 2025-10-06 20:24:37 | MASTER-Tunka | (02h 42m 02.27s , -03d 51m 48.1s) | C | 5 | 16.1 | 1177 | 2025-10-06 20:24:37 | MASTER- | (02h 41m 39.20s , -03d 46m 47.7s) | C | 5 | 15.8 | 1185 | 2025-10-06 20:24:46 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 48.5s) | C | 5 | 16.2 | 1185 | 2025-10-06 20:24:46 | MASTER- | (02h 41m 39.19s , -03d 46m 48.0s) | C | 5 | 15.9 | 1194 | 2025-10-06 20:24:54 | MASTER-Tunka | (02h 42m 02.25s , -03d 51m 48.6s) | C | 5 | 16.2 | 1194 | 2025-10-06 20:24:54 | MASTER- | (02h 41m 39.20s , -03d 46m 48.2s) | C | 5 | 15.9 | 1203 | 2025-10-06 20:25:03 | MASTER- | (02h 41m 39.21s , -03d 46m 48.2s) | C | 5 | 15.9 | 1203 | 2025-10-06 20:25:03 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 48.7s) | C | 5 | 16.1 | 1214 | 2025-10-06 20:25:14 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 49.0s) | C | 5 | 16.1 | 1214 | 2025-10-06 20:25:14 | MASTER- | (02h 41m 39.20s , -03d 46m 48.7s) | C | 5 | 16.0 | 1222 | 2025-10-06 20:25:23 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 49.3s) | C | 5 | 16.2 | 1222 | 2025-10-06 20:25:23 | MASTER- | (02h 41m 39.21s , -03d 46m 49.0s) | C | 5 | 15.9 | 1231 | 2025-10-06 20:25:31 | MASTER-Tunka | (02h 42m 02.27s , -03d 51m 49.8s) | C | 5 | 16.1 | 1231 | 2025-10-06 20:25:31 | MASTER- | (02h 41m 39.21s , -03d 46m 49.3s) | C | 5 | 15.9 | 1270 | 2025-10-06 20:26:10 | MASTER-Tunka | (02h 42m 02.26s , -03d 51m 50.6s) | C | 5 | 16.1 | 1270 | 2025-10-06 20:26:10 | MASTER- | (02h 41m 39.20s , -03d 46m 50.5s) | C | 5 | 16.0 | 1347 | 2025-10-06 20:26:30 | MASTER-Kislovodsk | (02h 39m 44.69s , -03d 40m 13.3s) | P- | 120 | 14.3 | 1347 | 2025-10-06 20:26:30 | MASTER-Kislovodsk | (02h 39m 55.49s , -04d 03m 29.7s) | P| | 120 | 13.7 | 1487 | 2025-10-06 20:28:50 | MASTER-Kislovodsk | (02h 39m 44.76s , -03d 40m 09.2s) | P- | 120 | 14.3 | 1487 | 2025-10-06 20:28:50 | MASTER-Kislovodsk | (02h 39m 55.53s , -04d 03m 26.9s) | P| | 120 | 13.8 | 1626 | 2025-10-06 20:31:10 | MASTER-Kislovodsk | (02h 39m 44.78s , -03d 40m 03.9s) | P- | 120 | 14.3 | 1626 | 2025-10-06 20:31:10 | MASTER-Kislovodsk | (02h 39m 55.58s , -04d 03m 23.2s) | P| | 120 | 13.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42133. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40201] GRB 251006B: BALROG localization (Fermi Trigger 781473909 / GRB 251006837)
by GCN Circulars 06 Oct '25

06 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42132 SUBJECT: GRB 251006B: BALROG localization (Fermi Trigger 781473909 / GRB 251006837) DATE: 25/10/06 20:36:55 GMT FROM: Jochen Greiner at MPE <jcgrog(a)mpe.mpg.de> T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 781473909 at 20:05:04 on 06 Oct. 2025 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60). The best-fit position is: RA(2000.0) = 41.9 deg Decl.(2000.0) = -6.8 deg The 1 sigma statistical error radius is 3.4 deg. We estimate an additional systematic error of 1 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB251006837/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB251006837/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB251006837/json View this GCN Circular online at https://gcn.nasa.gov/circulars/42132. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40200] GRB 251006B: Fermi GBM Final Real-time Localization
by GCN Circulars 06 Oct '25

06 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42131 SUBJECT: GRB 251006B: Fermi GBM Final Real-time Localization DATE: 25/10/06 20:15:37 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 20:05:04 UT on 6 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251006B (trigger 781473909.040226 / 251006837). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 40.5, Dec = -4.0 (J2000 degrees, equivalent to J2000 02h 42m, -4d 00'), with a statistical uncertainty of 1.2 degrees. The angle from the Fermi LAT boresight is 105.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251006837/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251006837/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251006837/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42131. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40199] GRB 251005C: VLT/X-shooter Imaging
by GCN Circulars 06 Oct '25

06 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42127 SUBJECT: GRB 251005C: VLT/X-shooter Imaging DATE: 25/10/06 18:04:22 GMT FROM: Massine El Kabir <m.elkabir(a)campus.unimib.it> GRB 251005C: VLT/X-shooter Imaging Muskan Yadav (U Rome), Yu-Han Yang (U Rome), Massine El Kabir (U Rome), Niccolò Passaleva (U Rome), Eleonora Troja (U Rome) report on behalf of the ERC BHianca team: We observed the field of GRB 251005C (K. L. Page et al., GCN 42113) with the Xshooter spectrograph on the ESO VLT UT3 (Melipal). Observations began at T+16.5 hours. We obtained a total exposure of 335 s using the acquisition and guiding (A&G) camera. Observations were carried out in the i’ filter at an average airmass of about 1.4 and seeing 0.75 arcsec. Within the XRT error region (Goad et al., GCN 42116) we detect a faint (i~24 AB mag) source at coordinates RA, Dec (J2000) = 05:02:44.03, +16:52:51.632. The object appears extended in our images. We also detect the SVOM/VT optical candidate (J. T. Palmeiro et al., GCN 42123) at a significantly fainter magnitude (i~24 AB mag), confirming its rapid fading. We thus suggest that this is the GRB optical counterpart. We thank the staff at the VLT, for the rapid execution of these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42127. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40198] GRB 251006A (short): Glowbug gamma-ray detection
by GCN Circulars 06 Oct '25

06 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42130 SUBJECT: GRB 251006A (short): Glowbug gamma-ray detection DATE: 25/10/06 20:09:57 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil> C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 251006A, which was also detected by Fermi/GBM (GCN 42124). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-10-06 13:27:33.944 with a duration of 0.26 s and a total significance of about 18.8 sigma. The light curve comprises a single peak with possible substructure. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS, and operated until 2024 April when it was put in safe storage on orbit. Glowbug was recently removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42130. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40197] GRB 251005C: COLIBRÍ optical observations
by GCN Circulars 06 Oct '25

06 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42129 SUBJECT: GRB 251005C: COLIBRÍ optical observations DATE: 25/10/06 18:58:06 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Alan M. Watson (UNAM), Francis Fortin (IRAP), Jean-Luc Atteia (IRAP), Benjamin Schneider (LAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (OCA), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU) , Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), and Antonio de Ugarte Postigo (LAM): We imaged the field of the Swift GRB 251005C (Page et al., GCN Circ. 42113) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2025-10-06 11:23 to 12:30 UTC (from 19.28 to 20.40 hours after the trigger) and obtained 38 minutes of simultaneous exposure in the i and z filters. The data were reduced and coadded with the tenue software and analyzed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. At the position of the XRT source reported by Goad et al. (GCN Circ. 42116) and at the position of the VT optical source reported by Palmerio et al. (GCN Circ. 42123), we do not detect any sources above our 3-sigma limits of i > 23.8 z > 23.3 However, at the position of the VT source there are hints of the presence of a faint resolved object at lower significance. Our results are consistent with the X-shooter photometry reported by Yadav et al. (GCN Circ. 42127). We caution that the apparent fading in the i band with respect to the earlier VT_R detection is not conclusive, as the VT_R band above 650 nm includes both i and z, and our limit in z alone is not much deeper than the original detection. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/42129. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40196] Fermi GRB 251006A: Global MASTER-Net observations report
by GCN Circulars 06 Oct '25

06 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42128 SUBJECT: Fermi GRB 251006A: Global MASTER-Net observations report DATE: 25/10/06 18:45:52 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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 251006A ( Fermi GBM team, GCN 42124) errorbox 16713 sec after notice time and 16748 sec after trigger time at 2025-10-06 18:06:43 UT, with upper limit up to 17.0 mag. The observations began at zenith distance = 42 deg. The sun altitude is -18.0 deg. The galactic latitude b = 4 deg., longitude l = 12 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3008484 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 16778 | 2025-10-06 18:06:43 | MASTER-SAAO | (17h 34m 02.34s , -16d 58m 33.7s) | C | 60 | 16.7 | 16778 | 2025-10-06 18:06:43 | MASTER-SAAO | (17h 32m 04.73s , -16d 43m 22.6s) | C | 60 | 16.8 | 16871 | 2025-10-06 18:08:16 | MASTER-SAAO | (17h 40m 13.62s , -14d 06m 21.6s) | C | 60 | 16.9 | 16871 | 2025-10-06 18:08:16 | MASTER-SAAO | (17h 38m 17.54s , -13d 51m 10.9s) | C | 60 | 17.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42128. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40195] GRB 251005C
by GCN Circulars 06 Oct '25

06 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42127 SUBJECT: GRB 251005C DATE: 25/10/06 18:04:22 GMT FROM: Massine El Kabir <m.elkabir(a)campus.unimib.it> GRB 251005C: VLT/X-shooter Imaging Muskan Yadav (U Rome), Yu-Han Yang (U Rome), Massine El Kabir (U Rome), Niccolò Passaleva (U Rome), Eleonora Troja (U Rome) report on behalf of the ERC BHianca team: We observed the field of GRB 251005C (K. L. Page et al., GCN 42113) with the Xshooter spectrograph on the ESO VLT UT3 (Melipal). Observations began at T+16.5 hours. We obtained a total exposure of 335 s using the acquisition and guiding (A&G) camera. Observations were carried out in the i’ filter at an average airmass of about 1.4 and seeing 0.75 arcsec. Within the XRT error region (Goad et al., GCN 42116) we detect a faint (i~24 AB mag) source at coordinates RA, Dec (J2000) = 05:02:44.03, +16:52:51.632. The object appears extended in our images. We also detect the SVOM/VT optical candidate (J. T. Palmeiro et al., GCN 42123) at a significantly fainter magnitude (i~24 AB mag), confirming its rapid fading. We thus suggest that this is the GRB optical counterpart. We thank the staff at the VLT, for the rapid execution of these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42127. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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