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[vsnet-grb-info 41393] Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB
by GCN Circulars 02 Jan '26

02 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43302 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 789047602/260102495 is not a GRB DATE: 26/01/02 13:09:36 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 789047602/260102495 at 11:53:17.07 UT on 02 January 2026, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to local particle activity." View this GCN Circular online at https://gcn.nasa.gov/circulars/43302. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41392] GRB 251230A / EP251230a: GECAM-B detection
by GCN Circulars 02 Jan '26

02 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43301 SUBJECT: GRB 251230A / EP251230a: GECAM-B detection DATE: 26/01/02 13:08:59 GMT FROM: guohx(a)ihep.ac.cn Hao-Xuan Guo, Chen-Wei Wang, Zheng-Hang Yu, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered in-flight by GRB 251230A / EP251230a at 2025-12-30T01:21:44.050 UTC (denoted as T0), which is also detected by Swift (Lanava et al., GCN #43252), EP-WXT (Li et al., GCN #43255 and Wang et al., GCN #43272) and Insight-HXMT/HE (Guo et al., GCN #43299). According to the GECAM-B light curve in about 70-6000 keV, this burst mainly consists of multi-pulses with a duration (T90) of 71.2 +4.6/-8.2 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb251230A.png Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS). View this GCN Circular online at https://gcn.nasa.gov/circulars/43301. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41391] GRB 260102A: SVOM/VT optical counterpart
by GCN Circulars 02 Jan '26

02 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43300 SUBJECT: GRB 260102A: SVOM/VT optical counterpart DATE: 26/01/02 12:45:56 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> C. Wu, H. L. Li, L. P. Xin, Y. L. Qiu, Y. N. Ma, Z. H. Yao, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, L. Lan, J. R. Xu, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA), W. J. Tan (IHEP) report on behalf of the SVOM team. SVOM performed an automatic slew on the burst GRB 260102A triggered by SVOM/ECLAIRs (sb26010201, Xie et al., GCN 42295) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. The observation began at 2026-01-02T04:13:40, i.e., 217 sec post trigger. An optical uncatalogued source was detected within errorbox of ECLAIRs (Xie et al., GCN 42295) and Swift-XRT source #2 (Evans et al., GCN 43298), compared to the Legacy survey catalog. The position is at R.A., Dec. = 183.95015, 48.25116 degrees, equivalent to: R.A. (J2000) = 12:15:48.03 Dec. (J2000) = 48:15:04.18 with an uncertainty of 0.5 arcsec. The magnitudes are: Mid_time Band Exposure Time Magnitude (AB) 242 sec VT_B 50 sec 19.98+/-0.06 242 sec VT_R 50 sec 18.46+/-0.03 872 sec VT_B 50 sec 21.40+/-0.16 872 sec VT_R 50 sec 20.21+/-0.10 Our photometry was not corrected for Galactic extinction. More follow-ups for this burst 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/43300. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41390] GRB 251230A / EP251230a: Insight-HXMT/HE detection
by GCN Circulars 02 Jan '26

02 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43299 SUBJECT: GRB 251230A / EP251230a: Insight-HXMT/HE detection DATE: 26/01/02 12:17:17 GMT FROM: guohx(a)ihep.ac.cn Hao-Xuan Guo, Chen-Wei Wang, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng (IHEP) report on behalf of the Insight-HXMT team: At 2025-12-30T01:22:22.000 (T0), Insight-HXMT/HE detected a burst, GRB 251230A / EP251230a, which is also detected by Swift (Lanava et al., GCN #43252) and EP-WXT (Li et al., GCN #43255 and Wang et al., GCN #43272). The Insight-HXMT/HE light curve mainly consists of multiple pulses with T90 of 54.4 +11.6/-8.4 s. The 1s peak rate, measured from T0-0.70 s, is 797 cnts/sec. Insight-HXMT/HE detected a total of 10,311 counts from this burst. The Insight-HXMT /HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251230A.png All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the Low-Gain mode with the energy range of about 300-3000 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org View this GCN Circular online at https://gcn.nasa.gov/circulars/43299. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41389] GRB 260102A: Swift ToO observations
by GCN Circulars 02 Jan '26

02 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43298 SUBJECT: GRB 260102A: Swift ToO observations DATE: 26/01/02 06:48:54 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a ToO observation of the SVOM/ECLAIRs-detected event GRB 260102A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021896 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the SVOM/ECLAIRs event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43298. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41388] GRB 260101A: Fermi GBM Observation
by GCN Circulars 02 Jan '26

02 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43297 SUBJECT: GRB 260101A: Fermi GBM Observation DATE: 26/01/02 05:59:57 GMT FROM: Glowbug DEV <boyan.a.hristov(a)nasa.gov> B. Hristov (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 00:56:30.65 UT on 01 January 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260101A (trigger 788921795/260101039). which was also detected by Swift (S. B. Cenko et al. 2026, GCN 43285), SVOM/GRM (Z. Yu et al. 2026, GCN 43292) and GECAM-B (C. Wang et al. 2026, GCN 43294). The Fermi GBM on-ground location is consistent with the one reported by Swift. The angle from the Fermi LAT boresight is 43 degrees. The GBM light curve consists of multiple emission episodes with a duration (T90) of about 27.4 s (50-300 keV). The time-averaged spectrum from T0 to T0+29.6 s s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.09 +/- 0.01 and the cutoff energy, parameterized as Epeak, is 143.5 +/- 1.5 keV. The event fluence (10-1000 keV) in this time interval is (6.7 +/- 0.12)e-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+25 s in the 10-1000 keV band is 9.6 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: sftp://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" View this GCN Circular online at https://gcn.nasa.gov/circulars/43297. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41387] EP260101a: refined analysis of the EP-WXT and EP-FXT observations
by GCN Circulars 02 Jan '26

02 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43296 SUBJECT: EP260101a: refined analysis of the EP-WXT and EP-FXT observations DATE: 26/01/02 04:56:23 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> M.-H. Zhang, Y.-L. Wang, W. Chen, H. Sun (NAO, CAS) on behalf of the Einstein Probe (EP) team: The fast X-ray transient EP260101a was detected by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Zhang et al., GCN 43288). The refined analysis of the WXT data shows that the event started at T0=2026-01-01T06:31:46 (UTC) and lasted for 200 seconds before the observation was interrupted by the autonomous follow-up. The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 1.3 x 10^21 cm^-2 and a photon index of 1.7 (-0.7/+0.7). The derived average unabsorbed 0.5-4 keV flux is 6.6 (-3.2/+2.0) x 10^(-11) erg/s/cm^2. The Follow-up X-ray Telescope (FXT) on board EP observed this source autonomously at 2026-01-01T06:38:27 (UTC), about 7 minutes after T0. The exposure time of this observation is 4674s. On-ground analysis of the FXT data found an uncatalogued source at R.A. = 46.0631, DEC = 39.4376 (J2000) with an uncertainty of about 10 arcsec (radius, 90% C.L. statistical and systematic), which is consistent with the WXT position. A significant decay was detected in the light curve during the initial phase of FXT observation. The average 0.5-10 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 1.3 x 10^21 cm^-2 and a photon index of 2.9 (-0.4/+0.3). The derived average unabsorbed 0.5-10 keV flux is 8.4 (-1.3/+1.2) x 10^(-13) erg/s/cm^2. We performed another ToO observation with EP-FXT, starting at 2026-01-01T11:08:28 (UTC), with an exposure time of 6950 s. The average 0.5-10 keV spectrum can be fitted with an absorbed power law with the same fixed Galactic hydrogen column density and a photon index of 3.5 (-1.1/+1.0). The derived average unabsorbed 0.5-10 keV flux is 8.6 (-4.1/+2.9) x 10^(-14) erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/43296. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41386] GRB 260102A: SVOM detection of a burst
by GCN Circulars 02 Jan '26

02 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43295 SUBJECT: GRB 260102A: SVOM detection of a burst DATE: 26/01/02 04:43:22 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Wenjin XIE (NAOC), Wenjun TAN (IHEP), Donhua ZHAO (NAOC), Chenwei WANG (IHEP) report on behalf of the SVOM mission team: At 2026-01-02T04:10:03 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260102A (SVOM burst-id sb26010201). 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 14 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 16.44 in the [8-120] keV energy band over a time window of 40.96 seconds starting at 2026-01-02T04:09:45. The localization of the best alert is R.A., Dec. 183.8803, 48.2583 degrees: R.A. (J2000) = 12h15m31.28s Dec. (J2000) = 48d15m29.77s with a 90% confidence level (C.L.) radius of 5.09 arcmin (including systematic error of 2 arcmin added in quadrature). SVOM/GRM detected the burst also. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb260102A.png SVOM slewed to the burst. SVOM/MXT and 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 Wenjin XIE: xiewj(a)bao.ac.cn. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/43295. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41385] GRB 260101A: GECAM-B detection
by GCN Circulars 02 Jan '26

02 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43294 SUBJECT: GRB 260101A: GECAM-B detection DATE: 26/01/02 04:42:19 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> Chen-Wei Wang, Zheng-Hang Yu, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered in-flight by GRB 260101A at 2026-01-01T00:56:34.100 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #43284), Swift (S. B. Cenko et al., GCN #43285), SVOM/GRM (Yu et al., GCN #43292). According to the GECAM-B light curve in about 70-6000 keV, this burst mainly consists of multi-pulses with a duration (T90) of 30.0 +6.0/-3.0 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb260101A.png Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS). View this GCN Circular online at https://gcn.nasa.gov/circulars/43294. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41384] GRB 260101A: NOT spectroscopic observations
by GCN Circulars 01 Jan '26

01 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43293 SUBJECT: GRB 260101A: NOT spectroscopic observations DATE: 26/01/01 21:05:21 GMT FROM: Andrea Saccardi at CEA/Irfu <andrea.saccardi(a)cea.fr> A. Saccardi (CEA/Irfu), L. Izzo (INAF/OACN and DARK/NBI), A. Martin-Carrillo (UCD), G. Corcoran (UCD), D. B. Malesani (DAWN/NBI and Radboud), K. Valeckas (NOT & NBI), report on behalf of a larger collaboration: We observed the optical afterglow (Cenko et al., GCN 43285; Perez-Fournon et al., GCN 43286; de Ugarte Postigo et al., GCN 43287) of GRB 260101A detected by Fermi (Fermi GBM team, GCN 43284), Swift (Cenko et al., GCN 43285) and SVOM/GRM (Yu et al., GCN 43292) with the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. A spectrum using grism #4 was secured starting on 2026 Jan 1 at 01:43:54 UT (47 min after the GRB trigger). Due to bad weather and seeing, we only got two spectra, one of which had a very short exposure time, resulting in a relatively low S/N for the stacked spectrum. The total exposure time is ~ 1500 s covering the wavelength range 3800-9300 AA. From the unfiltered acquisition 30 s image we measure an AB magnitude of 17.30 +/- 0.07, at a mid-time of 45 minutes after the trigger. Our photometry was calibrated against nearby stars from the r-band PanSTARRS catalogue and not corrected for Galactic extinction. In a preliminary reduction of the stacked spectrum, we detect a trace over the whole observed wavelength range. At the redshift of z = 2.623 reported by de Ugarte Postigo et al. (GCN 43287) we identify different absorption features, which we interpret as due to Si IV, C IV, and Al II. We note that we do not see a clear absorption corresponding to the weak Ly-alpha. Further analysis is ongoing. View this GCN Circular online at https://gcn.nasa.gov/circulars/43293. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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