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[vsnet-grb-info 40776] GRB 251116C: SVOM/VT optical upperlimit
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42712 SUBJECT: GRB 251116C: SVOM/VT optical upperlimit DATE: 25/11/17 09:39:51 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Y. N. Ma, Z. H. Yao, Y. Xu, X. H. Han, J. Wang, 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), M. Pillas (IAP), M.G. Bernardini (INAF-OAB, LUPM) report on behalf of the SVOM/VT team. SVOM/VT performed an automatic slew on GRB 251116C (SVOM burst-id sb25111605, Pillas et al., GCN 42703). The observation started on 2025-11-16T17:04:52 UT (i.e. 1.1 hour post trigger) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. No uncatalogued sources are detected in single or stacked images within ECL's error box (Pillas et al., GCN 42703) and the Swift/XRT source #1 and source #2's error box (https://www.swift.ac.uk/SVOM/SVOM_FIELD00051/) The 3 sigma limit magnitudes are derived as below: Mid time | Band | Exposure Time | 3 sigma limit magnitude 1.4 hour VT_B 23*50 sec >23.3 mag 1.4 hour VT_R 28*50 sec >23.4 mag Our result is consistent with the LCO's observation (Turpin et al., GCN 42705). 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/42712. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40775] GRB 251025B: further Mondy optical observations
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42711 SUBJECT: GRB 251025B: further Mondy optical observations DATE: 25/11/17 08:08:51 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We continued observations of the field of the GRB 251025B (Hussein et al., GCN 42437) in the R-filter with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy) taking several frames with 120 s exposures on Oct. 27-29 and Nov. 1, 2025. The optical counterpart (Wu et al., GCN 42438; Gress et al., GCN 42439; Wu et al., GCN 42440; Beardmore et al., GCN 42445; Mohan et al., GCN 42447; Hernández Funget al., GCN 42450; Pereyra et al., GCN 42452; Li et al., GCN 42453; Mo et al., GCN 42459; Rakotondrainibe et al., GCN 42460; Rajabov et al., GCN 42466; Saccardi et al., GCN 42472; Freeberg et al., GCN 42474; Volnova et al., GCN 42475; Gupta et al., GCN 42500; Mohan et al., GCN 42503; Adami et al., GCN 42547) is clearly detected in the stacked frame of every epoch. Preliminary photometry is the following: Date UT start t-T0 Exp. Filter OT Err. UL (mid,days) (n*s) (3sigma) 2025-20-27 15:53:18 2.08280 30*120 R 21.22 0.07 22.8 2025-10-28 16:11:51 3.11396 29*120 R 21.82 0.17 22.3 2025-10-29 15:14:24 4.03841 5*120 R 21.95 0.25 22.2 2025-11-01 15:12:37 7.07680 60*120 R 22.94 0.26 23.2 The photometry is based on several nearby SDSS stars (R-magnitudes Lupton's transformation) and is not corrected for the Galactic extinction, all magnitudes are in Vega system. View this GCN Circular online at https://gcn.nasa.gov/circulars/42711. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40774] GRB 251111A: Mondy optical upper limit
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42710 SUBJECT: GRB 251111A: Mondy optical upper limit DATE: 25/11/17 08:05:29 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We observed the field of the GRB 251111A (Cheng et al., GCN 42637) with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy) in the R-filter starting Nov., 11, 2025, UT 16:26:22, and taking several frames with 120 s exposures. In the stacked frame we do not detect the optical counterpart (López-Cámara et al., GCN 42638; Wu et al., GCNs 42639, 42641; Ma et al., GCN 42647). Preliminary photometry is the following: Date UT start t-T0 Exp. Filter OT Err. UL (mid,days) (n*s) (3sigma) 2025-11-11 16:26:22 0.48686 25*120 R n/d n/d 22.1 The photometry is based on several nearby SDSS stars (R-magnitudes Lupton's transformation) and is not corrected for the Galactic extinction, all magnitudes are in Vega system. View this GCN Circular online at https://gcn.nasa.gov/circulars/42710. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40773] GRB 251116B: EP-FXT follow-up observation
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42709 SUBJECT: GRB 251116B: EP-FXT follow-up observation DATE: 25/11/17 03:44:02 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> D.Y. Li, G. J. Yang, C. L. Guo (NAO, CAS), D. Z. Du (ZJU), R. X. Hu (WHU), Q. J. Huang(PMO, CAS), Y. Liu (NAO, CAS) on behalf of the Einstein Probe (EP) team: EP-FXT performed a follow-up observation of the SVOM/ECLAIRs-detected burst GRB 251116B (SVOM/sb25111604, Pillas et al., GCN #42702) at 2025-11-16 17:13:25 (UTC), about 1.7 hours after the SVOM/ECLAIRs trigger, with an exposure time of 5832s. Six uncataloged sources are detected within the ECLAIRs error circle. Preliminary analysis on these sources is automatically conducted, and the details are listed as follows. EPF_J011551.9-410700 RA (J2000): 18.9664 Dec (J2000): -41.1167 Flux: 5.54 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.68 x 10^-14 erg/s/cm2 (1 sigma) EPF_J011518.5-405816 RA (J2000): 18.8272 Dec (J2000): -40.971 Flux: 1.35 x 10^-13 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 4.97 x 10^-14 erg/s/cm2 (1 sigma) EPF_J011442.3-410511 RA (J2000): 18.6761 Dec (J2000): -41.0863 Flux: 4.54 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.58 x 10^-14 erg/s/cm2 (1 sigma) EPF_J011604.1-410246 RA (J2000): 19.0172 Dec (J2000): -41.0461 Flux: 6.74 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.73 x 10^-14 erg/s/cm2 (1 sigma) EPF_J011523.3-410250 RA (J2000): 18.8471 Dec (J2000): -41.0471 Flux: 6.72 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 2.29 x 10^-14 erg/s/cm2 (1 sigma) EPF_J011535.7-410502 RA (J2000): 18.8988 Dec (J2000): -41.0839 Flux: 7.66 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.59x 10^-14 erg/s/cm2 (1 sigma) View this GCN Circular online at https://gcn.nasa.gov/circulars/42709. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40772] LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42708 SUBJECT: LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate DATE: 25/11/17 00:04:59 GMT FROM: Jyotirmaya Mohanta at University of Tsukuba <s2430161(a)u.tsukuba.ac.jp> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S251116en during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2025-11-16 23:22:21.761 UTC (GPS time: 1447370559.761). The candidate was found by the Aframe [1], cWB [2], cWB BBH [3], GstLAL [4], MBTA [5], MLy [6], PyCBC Live [7], and SPIIR [8] analysis pipelines. S251116en 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/S251116en The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), BNS (<1%), or NSBH (<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%. [9] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [9] 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: * amplfi.multiorder.fits,0, an initial localization generated by AMPLFI [10], distributed via GCN and SCiMMA notices about 25 seconds after the candidate event time. * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [11], 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,0. For the bayestar.multiorder.fits,0 sky map, the 90% credible region is 788 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1741 +/- 490 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] Skliris et al. PRD 110, 104034 (2024) doi:10.1103/PhysRevD.110.104034 [7] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [8] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023 [9] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [10] Chatterjee et al. MLST 5, 045030 (2024) doi:10.1088/2632-2153/ad8982 [11] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/42708. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40771] LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
by GCN Circulars 16 Nov '25

16 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42707 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory DATE: 25/11/16 23:22:33 GMT FROM: Sean MacBride at University of Zurich <sean.p.macbride(a)gmail.com> Sean MacBride (University of Zurich), Erin Howard, Ian Sullivan, Peter Yoachim, Eric Bellm (University of Washington), Shreya Anand (Stanford University), Federica Bianco (University of Delaware), Tiago Ribeiro, Lynne Jones, Alysha Shugart, Narayan Khadka, Kshitija Kelkar, Danica Zilkova, Kevin Fanning, Paulina Venegas, Kate Napier, Erik Dennihy, Anastasia Alexov, Bob Blum (NSF-DOE Vera C Rubin Observatory), Yousuke Utsumi (National Astronomical Observatory of Japan), Robert Lupton (Princeton University), Keith Bechtol (University of Wisconsin-Madison), reporting on behalf of NSF-DOE Vera C Rubin Observatory: We observed the localization region of the sub-solar mass merger S251112cm, reported by LIGO/Virgo/KAGRA (GCN 42650, GCN 42690) with the 9.6 square degree field of view LSST Camera mounted on the 8.4-m Simonyi Survey Telescope at the Vera C. Rubin Observatory. As reported in GCN 42690, S251112cm has a reported 90% localization area of 1681 square degrees and an expected false alarm rate of approximately one in four years. This is the first Target-of-Opportunity observation with Rubin Observatory since the transition to operations in late October 2025. Rubin Observatory is in an early operations period of continued system optimization, prior to beginning sustained LSST observations [1]. During this period, data quality and acquisition rate are variable. Not all data products that will be available during the Legacy Survey of Space and Time (LSST) operations are currently available [2]. Observations were conducted through engagement of the new Rubin Target-of-Opportunity advisory board, as a sub-solar mass merger does not meet the typical alert quality criteria for Rubin Target-of-Opportunity (ToO) observation [3]. The observing strategy for this event is to image the localization area in LSST g and i bands, with one 30 second visit for each band, on nights 0, 2, 4, and 6 of the observing campaign. On November 15 2025, at 01:49:27 UTC, we began observing the localization region of S251112cm, using the initial localization information provided in GCN 42650. We observed 39.2% (849.1 deg^2) of the localization area in the g-band, and 33.5% (754.9 deg^2) of the localization area in the i band. The difference in coverage was due to the localization area of S251112cm setting early in the night in Chile, before the telescope could observe the region in i band. For these observations, we reached a median depth of 24.8 mag in g band, 23.7 mag in the i band. Due to the lack of prior Rubin observations in most of the imaging area, we performed image differencing against DECam templates. To support the usage of DECam templates, we devised a custom image processing task to create DECam templates from DES templates for use with LSSTCam observations. Apart from the DECam template task, we utilize the standard LSST data release production pipeline to obtain difference images and photometry on difference image sources [4]. With only a single epoch of observations at Rubin Observatory, we are unable to characterize viable candidates from Rubin observations alone. Here, we report on candidates reported in GCN 42658, 42663, 42666, 42675, 42677, 42681, 42682, and 42691. We do not recover several candidates from these GCN’s for one of many reasons: lack of signal in the difference images, poor image subtraction near the source, or a lack of imaging in the region. Here, we report the candidates that pass these criteria, and comment on any notable nearby galaxies, given the reported luminosity distance from LVK (GCN 42650). We perform visual inspection on difference images that are coincident with previously reported candidates. We positively detect AT2025adgq, AT2025adhf, AT2025adkl, AT2025adjp, and AT2025addc. AT2025adhf and AT2025adkl were only detected unambiguously in one band (g and i respectively). Whether they are not detected in the other band is still under investigation.. AT2025adgq is detected unambiguously in two bands, separated from a host galaxy by ~10 arcseconds. AT2025adhf is nuclear to a barred spiral galaxy (WISEA J024344.38-551906.1), but its WISE colors are not consistent with the host being an AGN. AT2025adkl is offset by 90’ from a galaxy within the NED volume (GCN 42653), slightly offset from a small distant galaxy, and detected unambiguously in one band. AT2025adjp and AT2025addc are isolated sources detected unambiguously in two bands. Here we report difference photometry for the aforementioned candidates: | AT Name | Observation Date [UTC] | RA | Dec | g | unc_g | i | unc_i | |------------|------------------------|---------|----------|-------|-------|-------|-------| | AT2025adgq | 2025-11-15 | 7.3825 | -39.5143 | 19.55 | 0.005 | 19.52 | 0.003 | | AT2025adhf | 2025-11-15 | 40.9351 | -55.3184 | - | - | 19.21 | 0.004 | | AT2025adkl | 2025-11-15 | 7.5357 | -41.0787 | 21.58 | 0.014 | - | - | | AT2025adjp | 2025-11-15 | 4.5396 | -33.8543 | 21.17 | 0.010 | 20.90 | 0.016 | | AT2025addc | 2025-11-15 | 73.8589 | -53.1621 | 20.91 | 0.009 | 21.25 | 0.022 | Analysis of these candidates is ongoing. We will continue to observe the localization area of S251112cm in the coming days according to the observing plan. We thank all who contributed to the design and implementation of the Vera C. Rubin Observatory Target-of-Opportunity system, including but not limited to, the LSST Transients and Variable Stars Science Collaboration Multiwavelength Characterization and Counterparts subgroup. We especially thank the Rubin Observatory observers, who are instrumental to the performance and success of the LSST. This material is based upon work supported in part by the National Science Foundation through Cooperative Agreements AST-1258333 and AST-2241526 and Cooperative Support Agreements AST-1202910 and 2211468 managed by the Association of Universities for Research in Astronomy (AURA), and the Department of Energy under Contract No. DE-AC02-76SF00515 with the SLAC National Accelerator Laboratory managed by Stanford University. Additional Rubin Observatory funding comes from private donations, grants to universities, and in-kind support from LSST-DA Institutional Members. [1] sitcomtn-005.lsst.io, §6 [2] lse-163.lsst.io [3] www.inspirehep.net/literature/2846480 [4] pstn-019.lsst.io View this GCN Circular online at https://gcn.nasa.gov/circulars/42707. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40770] GRB 251116B: LCO optical upper limits
by GCN Circulars 16 Nov '25

16 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42706 SUBJECT: GRB 251116B: LCO optical upper limits DATE: 25/11/16 20:59:01 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> D. Turpin, A. Saccardi, J. T. Palmerio (CEA/Irfu), L. P. Xin, C. Wu (NAOC), B. Cordier (CEA/Irfu), M. Pillas (IAP), M.G. Bernardini (INAF-OAB, LUPM), report on behalf of the SVOM mission team: We observed the field of GRB 251116B (Pillas et al., GCN 42702) with the LCO 1m telescope at the South African Astronomical Observatory (SAAO) equipped with the Sinistro instrument. Our observation started at 2025-11-16T18:42:46, about 3.1 hours after the SVOM/ECLAIRs trigger time. We obtained 3x200 s exposures in the SDSS r and the Pan-STARRS z filters. No uncatalogued source was identified in our stacked frames after subtraction against the Legacy Survey DR10 catalog image. We measure the following upper limits (5 sigma) calibrated against the SkyMapper DR4 catalog, and not corrected for Galactic extinction: r = 22.1 (AB) T_mid - T0 = 3.26 hr z = 20.1 (AB) T_mid - T0 = 3.98 hr This project is funded by the SVOM collaboration. View this GCN Circular online at https://gcn.nasa.gov/circulars/42706. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40769] GRB 251116C: LCO optical upper limits
by GCN Circulars 16 Nov '25

16 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42705 SUBJECT: GRB 251116C: LCO optical upper limits DATE: 25/11/16 20:07:59 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> D. Turpin, A. Saccardi, J. T. Palmerio (CEA/Irfu), L. P. Xin (NAOC), C. Wu (NAOC), B. Cordier (CEA/Irfu), M. Pillas (IAP), M.G. Bernardini (INAF-OAB, LUPM), report on behalf of the SVOM mission team: We observed the field of GRB 251116C (Pillas et al., GCN 42703) with the LCO 1m telescope at the South African Astronomical Observatory (SAAO) equipped with the Sinistro instrument. Our observation started at 2025-11-16T18:45:47 about 2.8 hours after the SVOM/ECLAIRs trigger time. We obtained 3x200 s exposures in the SDSS r and 3x200s exposures in the PanSTARRS z filters. No any uncatalogued source was identified in our stacked frames. We measure the following upper limits (5 sigma) calibrated against the PanSTARRS DR1 catalog, and not corrected for Galactic extinction: r = 21.5 (AB) T_mid - T0 = 3.1 hr z = 19.9 (AB) T_mid - T0 = 2.9 hr This project is funded by the SVOM collaboration. View this GCN Circular online at https://gcn.nasa.gov/circulars/42705. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40768] SVOM GRB251116.66: Global MASTER-Net observations report
by GCN Circulars 16 Nov '25

16 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42704 SUBJECT: SVOM GRB251116.66: Global MASTER-Net observations report DATE: 25/11/16 16:56:29 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) was pointed to the SVOM GRB251116.66 (trigger No 1763308636,22h 21m 03.65s , -10d 24m 37.8s, R=0.1302) errorbox 25 sec after notice time and 310 sec after trigger time at 2025-11-16 16:02:26 UT, with upper limit up to 13.6 mag. The observations began at zenith distance = 83 deg. The sun altitude is -56.4 deg. The galactic latitude b = -51 deg., longitude l = 52 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3043922 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 341 | 2025-11-16 16:02:26 | MASTER-Tunka | (22h 21m 03.35s , -10d 19m 13.2s) | P- | 60 | 13.6 | 341 | 2025-11-16 16:02:26 | MASTER- | (22h 20m 46.89s , -10d 14m 22.2s) | C | 60 | 16.6 | 404 | 2025-11-16 16:03:30 | MASTER-Tunka | (22h 21m 03.18s , -10d 19m 14.1s) | P- | 60 | 13.3 | 405 | 2025-11-16 16:03:30 | MASTER- | (22h 20m 45.91s , -10d 14m 11.5s) | C | 60 | 16.6 | 468 | 2025-11-16 16:04:33 | MASTER-Tunka | (22h 21m 03.13s , -10d 19m 13.7s) | P- | 60 | 13.4 | 468 | 2025-11-16 16:04:33 | MASTER- | (22h 20m 45.80s , -10d 14m 11.6s) | C | 60 | 16.4 | 532 | 2025-11-16 16:05:37 | MASTER-Tunka | (22h 21m 03.20s , -10d 19m 09.1s) | P- | 60 | 13.5 | 532 | 2025-11-16 16:05:37 | MASTER- | (22h 20m 45.69s , -10d 14m 13.4s) | C | 60 | 16.3 | 596 | 2025-11-16 16:06:42 | MASTER-Tunka | (22h 21m 02.88s , -10d 19m 13.7s) | P- | 60 | 13.0 | 596 | 2025-11-16 16:06:42 | MASTER- | (22h 20m 45.81s , -10d 14m 10.6s) | C | 60 | 16.3 | 660 | 2025-11-16 16:07:45 | MASTER-Tunka | (22h 21m 02.81s , -10d 19m 14.0s) | P- | 60 | 13.3 | 723 | 2025-11-16 16:08:49 | MASTER-Tunka | (22h 21m 02.83s , -10d 19m 13.6s) | P- | 60 | 13.1 | 723 | 2025-11-16 16:08:49 | MASTER- | (22h 20m 45.60s , -10d 14m 12.6s) | C | 60 | 16.3 | 794 | 2025-11-16 16:09:59 | MASTER-Tunka | (22h 21m 02.55s , -10d 19m 16.7s) | P- | 60 | 13.0 | 794 | 2025-11-16 16:09:59 | MASTER- | (22h 20m 45.36s , -10d 14m 16.4s) | C | 60 | 16.3 | 857 | 2025-11-16 16:11:03 | MASTER-Tunka | (22h 21m 02.58s , -10d 19m 14.6s) | P- | 60 | 12.3 | 857 | 2025-11-16 16:11:03 | MASTER- | (22h 20m 45.53s , -10d 14m 12.8s) | C | 60 | 16.2 | 921 | 2025-11-16 16:12:07 | MASTER-Tunka | (22h 21m 02.72s , -10d 19m 10.5s) | P- | 60 | 13.1 | 921 | 2025-11-16 16:12:07 | MASTER- | (22h 20m 44.78s , -10d 14m 31.2s) | C | 60 | 16.3 | 985 | 2025-11-16 16:13:10 | MASTER-Tunka | (22h 21m 02.34s , -10d 19m 15.4s) | P- | 60 | 12.5 | 1068 | 2025-11-16 16:14:34 | MASTER-Tunka | (22h 21m 02.35s , -10d 19m 11.9s) | P- | 60 | 12.7 | 1132 | 2025-11-16 16:15:37 | MASTER-Tunka | (22h 21m 02.11s , -10d 19m 15.6s) | P- | 60 | 12.4 | 1132 | 2025-11-16 16:15:37 | MASTER- | (22h 20m 43.68s , -10d 14m 23.0s) | C | 60 | 16.2 | 1195 | 2025-11-16 16:16:41 | MASTER-Tunka | (22h 21m 01.96s , -10d 19m 17.1s) | P- | 60 | 12.0 | 1322 | 2025-11-16 16:18:48 | MASTER-Tunka | (22h 21m 01.71s , -10d 19m 17.4s) | P- | 60 | 12.0 | 1323 | 2025-11-16 16:18:48 | MASTER- | (22h 20m 43.97s , -10d 14m 36.1s) | C | 60 | 15.9 | 1386 | 2025-11-16 16:19:51 | MASTER-Tunka | (22h 21m 01.46s , -10d 19m 21.7s) | P- | 60 | 12.0 | 1450 | 2025-11-16 16:20:55 | MASTER-Tunka | (22h 21m 01.38s , -10d 19m 19.5s) | P- | 60 | 12.3 | 1577 | 2025-11-16 16:23:02 | MASTER-Tunka | (22h 21m 01.10s , -10d 19m 17.9s) | P- | 60 | 12.3 | 1641 | 2025-11-16 16:24:06 | MASTER-Tunka | (22h 21m 01.02s , -10d 19m 18.5s) | P- | 60 | 12.0 | 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/42704. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40767] GRB 251116C: SVOM detection of a burst
by GCN Circulars 16 Nov '25

16 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42703 SUBJECT: GRB 251116C: SVOM detection of a burst DATE: 25/11/16 16:22:19 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> M. Pillas (IAP), M.G. Bernardini (INAF-OAB, LUPM), M. Brunet (IRAP), A. Saccardi (CEA/Irfu), report on behalf of the SVOM mission team: At 2025-11-16T15:57:41 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251116C (SVOM burst-id sb25111605). 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 3 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 12.47 in the [5-20] keV energy band over a time window of 40.96 seconds starting at 2025-11-16T15:57:36. The localization of the best alert is R.A., Dec. 335.3182, -10.4239 degrees: R.A. (J2000) = 22h21m16.37s Dec. (J2000) = -10d25m26.01s with a 90% confidence level (C.L.) radius of 6.49 arcmin (including systematic error of 2 arcmin added in quadrature). SVOM slewed to the burst. No X-ray observation could be performed by SVOM/MXT for the time being. No optical observation could be performed by SVOM/VT for the time being. 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 Marion Pillas: marion.pillas(a)iap.fr. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42703. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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