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

[vsnet-grb-info 41058] GRB 251203B : SVOM trigger sb25120304 is not a GRB
by GCN Circulars 03 Dec '25

03 Dec '25

TITLE: GCN CIRCULAR NUMBER: 42981 SUBJECT: GRB 251203B : SVOM trigger sb25120304 is not a GRB DATE: 25/12/03 21:50:09 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> M. Brunet, N. A. Webb (IRAP), D. B. Malesani (DAWN/NBI and Radboud),report on behalf of the SVOM mission team: At 2025-12-03T18:10:27 SVOM issued an alert with burst-id: sb25120304. The following circulars have been published regarding this event: GCN 42973, GCN 42974, GCN 42978, GCN 42979, with the event labelled as GRB 252103B. Given the VT (Palmerio et al., GCN 42978), LCO (Malesani et al., GCN 42979), and XRT observations (https://www.swift.ac.uk/SVOM/SVOM_FIELD00054/), this event is most likely associated with a flare from the star Gaia DR3 2534635509050352256 (also a historical X-ray emitter), and is no longer considered a GRB. We apologize for any inconvenience this may have caused. The Burst Advocate (BA) on shift for this alert is Marius Brunet: mbrunet(a)irap.omp.eu. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42981. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41057] GRB 251203C: LCO optical upper limits
by GCN Circulars 03 Dec '25

03 Dec '25

TITLE: GCN CIRCULAR NUMBER: 42980 SUBJECT: GRB 251203C: LCO optical upper limits DATE: 25/12/03 21:31:09 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> D. Turpin, A. Saccardi (CEA/Irfu), D. B. Malesani (DAWN/NBI and Radboud), J. T. Palmerio (CEA/Irfu), L. P. Xin, C. Wu (NAOC), B. Cordier (CEA/Irfu), M. Brunet, N. A. Webb (IRAP), report on behalf of the SVOM mission team: We observed the field of the SVOM GRB 251203C (Brunet et al., GCN 42976) with the LCO 1m telescope at South African Astronomical Observatory equipped with the Sinistro instrument. Our observation started on 2025-12-03 at 19:05:17 UT (about 31 min after the trigger) and we obtained 3x200 s exposures in the SDSS r and 2x200 s exposures in the Pan-STARRS z filters. In the stacked image, we do not detect any new source within the ECLAIRs error circle. We measure the following upper limits calibrated against the Pan-STARRS catalog, and not corrected for Galactic extinction: r > 20.2 AB (mid-time 37 min after the trigger); z > 19.0 AB (mid-time 58 min after the trigger). This project is funded by the SVOM collaboration. View this GCN Circular online at https://gcn.nasa.gov/circulars/42980. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41056] GRB 251203B: LCO optical upper limits
by GCN Circulars 03 Dec '25

03 Dec '25

TITLE: GCN CIRCULAR NUMBER: 42979 SUBJECT: GRB 251203B: LCO optical upper limits DATE: 25/12/03 21:22:36 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> D. B. Malesani (DAWN/NBI and Radboud), D. Turpin, A. Saccardi, J. T. Palmerio (CEA/Irfu), L. P. Xin, C. Wu (NAOC), B. Cordier (CEA/Irfu), M. Brunet, N. A. Webb (IRAP), report on behalf of the SVOM mission team: We observed the field of the SVOM GRB 251203B (Brunet et al., GCN 42973) with the LCO 1m telescope at South African Astronomical Observatory equipped with the Sinistro instrument. Our observation started on 2025-12-03 at 19:14:38 UT (about 64 min after the trigger) and we obtained 3x200 s exposures in the SDSS r and 3x200 s exposures in the PanSTARRS z filters. In the stacked image, we do not detect any new source within the MXT error circle. We measure the following upper limits calibrated against the Pan-STARRS catalog, and not corrected for Galactic extinction: r > 20.8 AB (mid-time 1.16 hr after the trigger); z > 20.1 AB (mid-time 1.29 hr after the trigger). As already noted by Brunet et al. (GCN 42973) and Palmerio et al. (GCN 42978), within the MXT error circle there is a bright star at RA = 01:13:26.89, Dec = +00:01:07.7, also a possible historical X-ray emitter. Recent Swift/XRT observations (https://www.swift.ac.uk/SVOM/SVOM_FIELD00054/) show this star to be coincident with the only X-ray source within the MXT error circle. This suggests the transient is due to activity from this star. In our z-band image, the star appears about 0.6 mag brighter than its archival Pan-STARRS magnitude (though we caution possible saturation effects), a behavior also consistent with a stellar flare origin of the burst. This project is funded by the SVOM collaboration. View this GCN Circular online at https://gcn.nasa.gov/circulars/42979. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41055] GRB 251203B: SVOM/VT optical observation
by GCN Circulars 03 Dec '25

03 Dec '25

TITLE: GCN CIRCULAR NUMBER: 42978 SUBJECT: GRB 251203B: SVOM/VT optical observation DATE: 25/12/03 20:48:28 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> J. T. Palmerio (CEA), D. B. Malesani (DAWN/NBI and Radboud), Y. L. Qiu, C. Wu, H. L. Li, L. P. Xin (NAOC) on behalf of the SVOM/VT team. After the trigger by SVOM/ECLAIRs at 2025-12-03T18:10:27 UTC (T0), SVOM performed an automatic slew on the burst location (Brunet et al., GCN 42973). SVOM/VT began observing the field at 2025-12-03T18:16:09, 341.62 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, no credible candidate is identified down to VT_R~21 mag within the error box provided by MXT (Brunet et al. GCN 42973). We note the presence of the bright star Gaia DR3 2534635509050352256 within the error box of MXT which appeared to fade in our observations from magnitude VT_B = 12.4 to 14.0 over the course of ~1 hr. Despite the difference in photometric filters, this is brighter than its catalogued magnitude of mag g = 15.2 in Pan-STARRS1. 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/42978. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41054] GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
by GCN Circulars 03 Dec '25

03 Dec '25

TITLE: GCN CIRCULAR NUMBER: 42977 SUBJECT: GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations DATE: 25/12/03 20:41:04 GMT FROM: A. Bochenek at Liverpool John Moores University <a.m.bochenek(a)2023.ljmu.ac.uk> A. Bochenek, D. A. Perley (LJMU) and A. Y. Q. Ho (Cornell) report: We observed the field of GRB 251202A/EP251202a (Fermi GBM team, GCN 42933; Bala et al., GCN 42957; Zhang et al., GCN 42937; Liang et al., GCN 42946) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained two epochs, separated by ~30 minutes, of 6x120s exposures with the SDSS r filter starting at 2025-12-03 03:24: UT, approximately 25.8 hours after trigger. We report detections in both epochs, at the position of the afterglow first reported by Li et al., GCN 42934: MJD (mid) T_mid-T_0 Filter Mag. (AB) 61012.15590 25.89 h r 19.99 ± 0.05 61012.17610 26.38 h r 20.18 ± 0.09 The seeing was poor throughout the observations, with the second epoch being more affected. The photometry was calibrated using nearby PanSTARRS secondary standards and was not corrected for extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/42977. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41053] GRB 251203C: SVOM detection of a burst
by GCN Circulars 03 Dec '25

03 Dec '25

TITLE: GCN CIRCULAR NUMBER: 42976 SUBJECT: GRB 251203C: SVOM detection of a burst DATE: 25/12/03 19:20:15 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> M. Brunet, N. A. Webb (IRAP), N. Dagoneau, M. Moita, D. Turpin (CEA) report on behalf of the SVOM mission team At 2025-12-03T18:33:50 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251203C (SVOM burst-id sb25120305). 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 11 alerts. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 11.74 in the [8-50] keV energy band over a time window of 10.20 seconds starting at 2025-12-03T18:33:45. The localization of the best alert is R.A., Dec. 51.7804, -7.3100 degrees: R.A. (J2000) = 3h27m07.31s Dec. (J2000) = -7d18m36.09s with a 90% confidence level (C.L.) radius of 6.85 arcmin (including systematic error of 2 arcmin added in quadrature). No immediate slew was performed on this burst. A SVOM ToO has been programmed for follow-up. 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 Marius Brunet: mbrunet(a)irap.omp.eu. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42976. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41052] SVOM GRB251203.77: Global MASTER-Net observations report
by GCN Circulars 03 Dec '25

03 Dec '25

TITLE: GCN CIRCULAR NUMBER: 42975 SUBJECT: SVOM GRB251203.77: Global MASTER-Net observations report DATE: 25/12/03 18:56:39 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) was pointed to the SVOM GRB251203.77 (trigger No 1764786825,03h 27m 07.30s , -07d 18m 36.0s, R=0.1142) errorbox 874 sec after notice time and 959 sec after trigger time at 2025-12-03 18:49:45 UT, with upper limit up to 13.4 mag. The observations began at zenith distance = 52 deg. The sun altitude is -55.8 deg. The galactic latitude b = -48 deg., longitude l = 192 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3059703 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 990 | 2025-12-03 18:49:45 | MASTER-Kislovodsk | (03h 24m 59.88s , -06d 56m 52.1s) | C | 60 | 13.4 | 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/42975. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41051] SVOM GRB251203.76: Global MASTER-Net observations report
by GCN Circulars 03 Dec '25

03 Dec '25

TITLE: GCN CIRCULAR NUMBER: 42974 SUBJECT: SVOM GRB251203.76: Global MASTER-Net observations report DATE: 25/12/03 18:56:30 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) was pointed to the SVOM GRB251203.76 (trigger No 1764785366,01h 13m 50.30s , -00d 00m 00.4s, R=0.1345) errorbox 927 sec after notice time and 1072 sec after trigger time at 2025-12-03 18:27:18 UT, with upper limit up to 14.1 mag. The observations began at zenith distance = 44 deg. The sun altitude is -52.1 deg. The galactic latitude b = -62 deg., longitude l = 136 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3059683 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 1103 | 2025-12-03 18:27:18 | MASTER-Kislovodsk | (01h 13m 06.79s , +00d 09m 15.4s) | C | 60 | 14.1 | 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/42974. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41050] GRB 251203B: SVOM detection of a burst
by GCN Circulars 03 Dec '25

03 Dec '25

TITLE: GCN CIRCULAR NUMBER: 42973 SUBJECT: GRB 251203B: SVOM detection of a burst DATE: 25/12/03 18:54:01 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> M. Brunet, N. A. Webb (IRAP), N. Dagoneau, M. Moita (CEA), report on behalf of the SVOM mission team At 2025-12-03T18:10:27 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251203B (SVOM burst-id sb25120304). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was only detected by the Image Trigger (IMT), which produced a sequence of 9 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 9.85 in the [5-20] keV energy band over a time window of 81.92 seconds starting at 2025-12-03T18:09:25. The localization of the best alert is R.A., Dec. 18.4596, -0.0001 degrees (J2000) with a 90% confidence level (C.L.) radius of 8.07 arcmin (including systematic error of 2 arcmin added in quadrature). SVOM slewed to the burst. SVOM/MXT began observing the field at 2025-12-03T18:18:55 UTC, 509 seconds after T0. Using onboard processed data we found an uncatalogued X-ray source located at R.A., Dec. 18.3720, 0.0157 degrees: R.A. (J2000) = 01h13m29.27s Dec. (J2000) = 00d00m56.42s with a 90% C.L. radius of 35.36 arcseconds. This location is 5.34 arcminutes from the ECLAIRs onboard position. This position may be improved as more data is received. We note the presence of an X-ray source (2E 0110.9-0014) located 20.06 arcsec away from the MXT position. 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 Marius Brunet: mbrunet(a)irap.omp.eu. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42973. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41049] GRB 251129A / EP251129a: SVOM/VT optical color bluer
by GCN Circulars 03 Dec '25

03 Dec '25

TITLE: GCN CIRCULAR NUMBER: 42972 SUBJECT: GRB 251129A / EP251129a: SVOM/VT optical color bluer DATE: 25/12/03 15:51:33 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> L. P. Xin, H. L. Li, Y. L. Qiu, C. Wu, Z. H. Yao, Y. N. Ma, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. R. Xu, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team. SVOM/VT performed further ToO observations for GRB 251129A / EP251129a triggered by SVOM/ECLAIRs (sb25112901, Tan et al., GCN 42877, GCN 42879) and Einstein Probe (Wu et al., GCN 42884). The observations showed the color of the afterglow (Evans, GCN 42888; Angulo et al., GCN 42880; Watson, GCN 42883; Wu et al., GCN 42882; Masi, GCN 42885; Li et al., GCN 42887; Page et al., GCN 42891; Lipunov et al., GCN 42892; Moskvitin et al., GCN 42897; Guziy et al., GCN 42899; Sanchez-Ramirez et al., GCN 42900; Jiang et al., GCN 42902; Yaqup et al., GCN 42942; Kuin et al., GCN 42959) was changed from VT_B-VT_R~0.30+/-0.03 mag at 0.5 hours to VT_B-VT_R~0+/-0.05 mag at around 4 to 50 hours post burst. The latest measurements are 21.8+/-0.1 mag in both channels at the mid time of 49.83 hours post burst with the exposure time of 47*70 sec. Our photometry was in AB magnitude and not corrected for Galactic extinction. More follow-up observations are encouraged. 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/42972. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

2025

2024

2023

2022

2021

vsnet-grb-info