February 2026 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 41699] GRB 260127A: GECAM-B observation
by GCN Circulars 02 Feb '26

02 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43596 SUBJECT: GRB 260127A: GECAM-B observation DATE: 26/02/02 03:09:30 GMT FROM: renyz16607(a)163.com Yang-Zhao Ren, Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered on-ground by GRB 260127A, at 2026-01-27T17:51:07.000 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN #43528) and Swift/BAT (Klingler et al., GCN #43529). According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of a pulse with a duration (T90) of 6 +1/-1 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb260127A.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/43596. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41698] GRB 260131A: NOT spectroscopic redshift z = 1.434
by GCN Circulars 01 Feb '26

01 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43595 SUBJECT: GRB 260131A: NOT spectroscopic redshift z = 1.434 DATE: 26/02/01 22:04:19 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani(a)nbi.ku.dk> A. Saccardi (CEA/Irfu), J. An (NAOC), G. Corcoran (UCD), B. Gompertz (Birmingham), L. Izzo (INAF/OAC and DARK/NBI), D. B. Malesani (DAWN/NBI and Radboud), A. Martin-Carrillo (UCD), B. Schneider (LAM), A de Ugarte Postigo (LAM), K. Valeckas (NOT and NBI), report on behalf of a larger collaboration: We observed the optical counterpart GOTO26akj / AT2026bwg (Gompertz et al., GCN 43586; Lee et al., GCN 43587) of the Fermi and MAXI GRB 260131A (Roberts, GCN 43585; a.k.a. GRB 260131B: Sugai et al., GCN 43580) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC spectrograph. We measure the afterglow brightness to be r = 18.98 +/- 0.02 (AB) at a mean epoch 2026 Feb 01 at 19:45:24 UT (37.1 hr after the burst), calibrated against nearby Pan-STARRS stars and not corrected for Galactic extinction. A spectrum consisting of 4x900 s exposures was secured starting on 2026 Feb 01 at 19:57 UT (37.3 hr after the Fermi/GBM trigger), using grism #4 which covers the wavelength range 3200-9600 AA. Based on a preliminary reduction of part of the spectra, a continuum is detected down to 3600 AA, setting an upper limit to the redshift z < 1.95 based on the lack of HI absorption. From the detection of several absorption features, among which Mg II 2804/2796, Fe II 2600, Fe II 2382, and Al III 1863/1855, we infer a redshift z = 1.434. Further analysis is ongoing. View this GCN Circular online at https://gcn.nasa.gov/circulars/43595. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41697] EP260131a: Liverpool Telescope optical upper limits
by GCN Circulars 01 Feb '26

01 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43594 SUBJECT: EP260131a: Liverpool Telescope optical upper limits DATE: 26/02/01 19:40:28 GMT FROM: A. Bochenek at Liverpool John Moores University <a.m.bochenek(a)2023.ljmu.ac.uk> A. Bochenek, D. A. Perley (LJMU), report: We observed the field of EP 260131a (Ding et al., GCN 43574, Wu et al. GCN 43583) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 8x150s exposures in SDSS r filter and 10x120s in SDSS z, starting at 2026-01-31 23:25:26 UT, approximately 19.9 hours after trigger. One z-band exposure had to be discarded due to telescope movement. We report non-detections in the stacked images in both filters at the position of the counterpart first reported by Li et al. GCN 43577 and Álvarez et al., GCN 43578, with 3-sigma upper limits being r > 22.05 and z > 21.90 mag. The photometry was obtained using nearby PanSTARRS secondary standards and was not corrected for extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43594. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41696] EP260131a: COLIBRÍ further observations
by GCN Circulars 01 Feb '26

01 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43593 SUBJECT: EP260131a: COLIBRÍ further observations DATE: 26/02/01 17:30:24 GMT FROM: globus(a)astro.unam.mx Benjamin Schneider (LAM), William H. Lee (UNAM), Alan M. Watson (UNAM), Noémie Globus (UNAM), Stéphane Basa (UAR Pytheas), Edilberto Aguilar-Ruiz (UNAM), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Jean-Luc Atteia (IRAP), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Asuka Kuwata (UNAM), Nikos Mandarakas (LAM), 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) report: We imaged the field of the EP260131a (Ding et al., GCN Circ. 43574; Wu et al, GCN Circ 43583) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-02-01 06:33 to 12:16 UTC (from 27.04 to 32.74 hours after the trigger) and obtained, respectively, 160 minutes of exposure in the r and z filters. The data were reduced and coadded with the COLIBRÍ ASU pipeline 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. The candidate optical counterpart reported by Li et al. (GCN Circ. 43577), Sánchez Álvarez et al (GCN Circ. 43578), Malesani et al. (GCN Circ 43581), Schneider et al. (GCN Circ. 43582), Schneider et al. (GCN Circ 43584), Mu el al. (GCN Circ 43588), and Yao et al. (GCN CIrc. 43589) is clearly detected in our data, with a preliminary magnitude of r ~ 22. We find that the optical counterpart fades with an average temporal power-law index of ~ -0.5. We encourage further observations. 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/43593. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41695] Konus-Wind detection of GRB 260128A / EP260128a
by GCN Circulars 01 Feb '26

01 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43592 SUBJECT: Konus-Wind detection of GRB 260128A / EP260128a DATE: 26/02/01 16:47:41 GMT FROM: Dmitry Frederiks at Ioffe Institute <fred(a)mail.ioffe.ru> D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long-duration GRB 260128A/EP260128a (Einstein Probe detection: Zhow et al., GCN 43549; Fermi-GBM Sub-Threshold Detection: Ravasio et al., GCN 43556) was detected by Konus-Wind (KW) in the waiting mode at T0=T0(KW)~23:40:00 UTC. A Bayesian block analysis of the KW data in the 20-1500 keV band reveals a >10 sigma count rate increase in the interval from ~T0-101 s to ~T0+61 s. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260128A/ The time-integrated spectrum of the burst (measured from from ~T0-101 s to ~T0+61 s) is best described in the 20 - 1500 keV range by a power law with exponential cutoff (CPL) model with alpha = -0.93 ± 0.99 and Ep = (103 ± 16) keV. The spectrum near the peak count rate (measured from ~T0-4 s to T0+14 s) is best described by a CPL model with alpha = -1.26 ± 0.30 and Ep = (178 ± 31) keV. The total burst fluence is (6.12 ± 2.89)x10^-6 erg/cm^2, and the 2.944 s peak energy flux, measured from T0+2.082 s, is (1.57 ± 0.44)x10^-7 erg/cm^2 (both in the 20 - 1500 keV energy range). All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/43592. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41694] GRB 260131A: Insight-HXMT/HE detection
by GCN Circulars 01 Feb '26

01 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43591 SUBJECT: GRB 260131A: Insight-HXMT/HE detection DATE: 26/02/01 15:06:33 GMT FROM: Xinghao Luo at IHEP <2952704891(a)qq.com> Xing-Hao Luo, Chen-Wei Wang, Chao Zheng, Hao-Xuan Guo, Xiao-Bo Li and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team: At 2026-01-31T06:39:31.400 (T0), Insight-HXMT/HE detected the long burst GRB 260131A, which is also detected by Fermi/GBM (Fermi GBM Team, GCN #43579) . The Insight-HXMT/HE light curve mainly consists of multiple pulses with a T90 of 7.0 +2.5/-1.0 s. The 1s peak rate, measured from T0+1.75 s, is 982 cnts/sec. Insight-HXMT/HE detected a total of 5366 counts form this burst. The HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb260131A.png All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the regular mode with the energy range of about 60-900 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://hxmten.ihep.ac.cn/ View this GCN Circular online at https://gcn.nasa.gov/circulars/43591. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41693] Konus-Wind detection of GRB 260131A/B
by GCN Circulars 01 Feb '26

01 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43590 SUBJECT: Konus-Wind detection of GRB 260131A/B DATE: 26/02/01 14:06:26 GMT FROM: Dmitry Frederiks at Ioffe Institute <fred(a)mail.ioffe.ru> D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long GRB 260131A/B (Fermi-GBM detection: The Fermi GBM team, GCN 43579, Roberts, GCN 43585; MAXI/GSC detection: Sugai et al., GCN 43580) triggered Konus-Wind (KW) at T0=23972.646 s UT (06:39:32.646). The burst consists of two separated emission pulses, peaked around ~T0 and to T0+215 s, respectively. The total duration of the burst is ~250 s. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260131_T23972/ As observed by Konus-Wind, the burst had a fluence of (4.14 ± 0.91)x10^-5 erg/cm^2 and a 64-ms peak energy flux, measured from T0 + 0.384 s, of (4.33 ± 0.52)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum (measured from T0 to T0+238 s) is best fit in the 20 keV - 15 MeV range by a GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.15 (-0.70,+1.61), the high energy photon index beta = -1.97 (-0.20,+0.14), the peak energy Ep = 124 (-40,+56) keV, chi2 = 83/97 dof. The spectrum near the peak count rate (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 15 MeV range by a GRB (Band) function with the following model parameters: the low-energy photon index alpha = -1.17 (-0.15,+0.17), the high energy photon index beta = -1.98 (-0.18,+0.10), the peak energy Ep = 300 (-68,+131) keV, chi2 = 74/79 dof. All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/43590. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41692] EP260131a: SVOM/VT optical observation
by GCN Circulars 01 Feb '26

01 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43589 SUBJECT: EP260131a: SVOM/VT optical observation DATE: 26/02/01 08:04:28 GMT FROM: zhyao(a)bao.ac.cn Z. H. Yao, C. Wu, L. P. Xin, H. L. Li, Y. N. Ma, Y. L. Qiu, X. H. Han, Y. Xu, 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) and S. D. Vergani (LUX-Paris Obs.) report on behalf of the SVOM/VT team. SVOM/VT performed a Target of Opportunity observation of EP260131a detected by EP/WXT (Ding et al., GCN 43574). SVOM/VT began observing the field at 2026-01-31T17:47:46.506 UTC, ~14.3 h after T0, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. With X-band data available, the optical counterpart (Li et al., GCN 43577; Álvarez et al., GCN 43578; Malesani et al., GCN 43581; Schneider et al., GCN 43582; Schneider et al., GCN 43584; Mu el al., GCN 43588) was detected in both VT_B and VT_R band within EP/WXT's (Ding et al., GCN 43574) and EP/FXT's (Wu et al., GCN 43583) error box. The position of this target is R.A., Dec. = 149.902458, -3.307450 degrees, corresponding to: R.A. (J2000) = 09:59:36.59 Dec. (J2000) = -03:18:26.82 with an uncertainty of 0.5 arcsec. The photometric measurements are as follows: mid time (h) | exposure time (s) | band | mag (AB) --------------|-------------------|------|------------- 15.50 | 40*70 | VT_B | 22.38+/-0.05 15.31 | 41*70 | VT_R | 21.70+/-0.03 Our photometry was not corrected for Galactic extinction. 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/43589. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41691] EP260131a: Xinglong optical upper limit
by GCN Circulars 01 Feb '26

01 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43588 SUBJECT: EP260131a: Xinglong optical upper limit DATE: 26/02/01 04:16:49 GMT FROM: Xinglong Observatory at National Astronomical Observatories (NAOC), Chinese Academy of Sciences (CAS) <xinglong(a)nao.cas.cn> Haiyang-Mu (NAOC),Junjie-Jin (NAOC), Feng-Xiao (NAOC), Pengliang-Du (NAOC), Zhou-Fan (NAOC), Hong-Wu (NAOC) report: Following the detection of EP260131a by EP-WXT (GCN Circular 43574,GCN Circular 43577,GCN Circular 43578), we observed the field of EP260131a using the 2.16-m telescope at Xinglong Observatory, NAOC. We obtained 300s r-band frames with a median time of (2026-01-31 16:25:55(UT)) 13 hr after the EP trigger. No uncatalogued optical transient is detected in the stacked images within the 3 arcmin EP/WXT error circle (GCN Circular 43574,GCN Circular 43578), down to 5-sigma limiting magnitudes of r ~ 19.1(not good day with thin cloud and bad seeing), calibrated with Pan-STARRS sources in the field. Also there is no apparent brightening for the catalogued sources within the error circle. Based on the location of the report(GCN Circular 43574,GCN Circular 43578), the target was not observed. View this GCN Circular online at https://gcn.nasa.gov/circulars/43588. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41690] GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
by GCN Circulars 01 Feb '26

01 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43587 SUBJECT: GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading DATE: 26/02/01 03:45:33 GMT FROM: William H. Lee at UNAM <wlee(a)astro.unam.mx> We observed the optical afterglow candidate AT2026bwg discovered by Gompertz et al. (GCN 43586), of GRB 260131A (Fermi/GBM Team, GCN 43579), also associated with GRB 260131B (Sugai et al., GCN 43580; Roberts et al., GCN 43585), using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-02-01 02:06 to 03:05 UTC (from 19.45 to 20.46 hours after the trigger) and obtained 23 minutes of simultaneous exposure in the r and z filters. The data were reduced, coadded, calibrated, and analyzed with the COLIBRÍ ASU pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. The optical counterpart is clearly detected with preliminary magnitudes of: r = 17.96 +/- 0.01, z = 17.61 +/- 0.01. Since the start of our observations, the source has faded with an apparent average temporal power-law index of -2.01 +/ 0.26 (in r) and -1.50 +/- 0.33 (in z). 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/43587. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0