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

[vsnet-grb-info 41829] GRB 260211A: EP-FXT follow-up observation
by GCN Circulars 13 Feb '26

13 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43721 SUBJECT: GRB 260211A: EP-FXT follow-up observation DATE: 26/02/13 14:06:23 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> R.D. Liang, M. J. Liu (NAOC), H. Z. Wu (HUST), H. Sun (NAOC) on behalf of the Einstein Probe (EP) team: EP-FXT performed a follow-up observation of the SVOM/ECLAIRs-detected burst GRB 260211A (SVOM/sb26021102, Gotz et al., GCN 43705) at 2026-02-11 21:16:34 (UTC), about 52 minutes after the SVOM/ECLAIRs trigger, with an exposure time of 4569 s. Two 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_J054755.7-002705 RA (J2000): 86.9816 Dec (J2000): -0.4505 Flux: 1.2432 x 10^-12 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 2.2401 x 10^-13 erg/s/cm2 (1 sigma) EPF_J054802.6-002834 RA (J2000): 87.0127 Dec (J2000): -0.4750 Flux: 3.1645 x 10^-13 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 4.0267x 10^-14 erg/s/cm2 (1 sigma) Note that the position of the second candidate is consistent with a known X-ray source 1eRASS J054803.1-002833. 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/43721. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41828] GRB 260211A: SVOM/VT optical observation
by GCN Circulars 13 Feb '26

13 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43720 SUBJECT: GRB 260211A: SVOM/VT optical observation DATE: 26/02/13 09:02:26 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, Y. N. Ma, C. Wu, Z. H. Yao, Y. L. Qiu, L. P. Xin, 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/Irfu), R. C. Chen (NJU), A. Li (BNU), W. K. Zheng (UCB) report on behalf of the SVOM/VT team. SVOM/VT performed ToO observation to GRB260211A detected by SVOM/Eclairs (sb26021102, Gotz et al., GCN 43705) and Fermi GBM (Hamburg et al., GCN 43713). The observation started at 2026-02-11T20:48:38 UTC, i.e., 1.41 hours post trigger in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. SVOM/VT performed ToO observation to GRB260211A detected by SVOM/Eclairs (sb26021102, Gotz et al., GCN 43705) and Fermi GBM (Hamburg et al., GCN 43713). The observation started at 2026-02-11T20:48:38 UTC, i.e., 1.41 hours post trigger in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. Following EP-FXT's detections, two optical candidates were detected only in VT_R images compared to the PanSTARRS catalogue: Source1 : R.A., Dec. (2000)= 86.978758, -0.450528 4.7 arcsecs from the center of FXT src-1 Source2 : R.A., Dec. (2000)= 86.977490, -0.453334 17.9 arcsecs from the center of FXT src-1 The positions are given with an uncertainty of 0.5 arcsec. The measurements in AB magnitudes are given below: ID. Mid time. Band Exposure Time Magnitude (AB) Source1. 2.35 hour VT_R 16*70 sec 22.5+/-0.3 mag 5.63 hour VT_R 12*70 sec >22.6 mag 1.52 hour VT_B 16*70 sec >23.0 mag 5.95 hour VT_B 6*70 sec >22.5 mag Source2. 2.35 hour VT_R 16*70 sec 21.9+/-0.2 mag 5.63 hour VT_R 12*70 sec 21.9+/-0.2 mag 1.52 hour VT_B 16*70 sec >23.0 mag 5.95 hour. VT_B 6*70 sec >22.5 mag Our photometry was not corrected for Galactic extinction. For source2, we notice that there is a faint source in the PanSTARRS image. More followup observation is encouraged to confirm the nature of the sources. 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/43720. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41827] GRB 260212A: Glowbug gamma-ray detection
by GCN Circulars 13 Feb '26

13 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43719 SUBJECT: GRB 260212A: Glowbug gamma-ray detection DATE: 26/02/13 03:41:12 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 260212A, which was also detected by Fermi/GBM (GCN 43716). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-02-12 17:49:06.400 with a duration of 10.5 s and a total significance of about 69 sigma. The light curve comprises two primary peaks at ~T0+1s and +10s. 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 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 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/43719. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41826] GRB 260211A: GOTO optical upper limit
by GCN Circulars 12 Feb '26

12 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43718 SUBJECT: GRB 260211A: GOTO optical upper limit DATE: 26/02/12 19:44:39 GMT FROM: I. Worssam at University of Birmingham <ixw352(a)student.bham.ac.uk> S. Belkin, I. Worssam, A. Kumar, D. O’Neill, G. Ramsay, B. P. Gompertz, R. Starling, M. Wortley, M. Kennedy, K. Ackley, M. Dyer, J. Lyman, K. Ulaczyk, D. Steeghs, D. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. Kotak, R. Breton, J. Casares, L. Nuttall, B. Godson, T. Killestein, M. Pursiainen, on behalf of GOTO collaboration: We report on optical observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al. 2024) in response to the SVOM detected GRB 260211A (Gotz et al., GCN 43705). Two epochs of observations covering the localisation area were taken at 2026-02-11 20:08:30 UT (+44min post trigger) and 2026-02-11 21:16:33 UT (+1.87h post trigger) utilising GOTO-North. Each observation consisted of 4x90 s exposures in the GOTO L-band (400-700 nm). Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations. No new transients that could be credibly associated with GRB 260211A were detected down to an average 5-sigma depth of 20.6 mag (AB), see also Globus et al., GCN 43707; Wu et al., GCN 43709; Konno et al., GCN 43715. GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester, the University of Birmingham and the Instituto de Astrofisica de Canarias (IAC). View this GCN Circular online at https://gcn.nasa.gov/circulars/43718. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41825] Fermi GRB 260212A: Global MASTER-Net observations report
by GCN Circulars 12 Feb '26

12 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43717 SUBJECT: Fermi GRB 260212A: Global MASTER-Net observations report DATE: 26/02/12 19:15:22 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) started inspect of the Fermi GRB 260212A ( Fermi GBM team, GCN 43716) errorbox 552 sec after notice time and 585 sec after trigger time at 2026-02-12 17:58:53 UT, with upper limit up to 18.0 mag. The observations began at zenith distance = 59 deg. The sun altitude is -37.1 deg. The galactic latitude b = 40 deg., longitude l = 111 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3132416 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 645 | 2026-02-12 17:58:53 | MASTER-Kislovodsk | (15h 16m 06.75s , +73d 36m 46.3s) | C | 120 | 18.0 | 786 | 2026-02-12 18:01:14 | MASTER-Kislovodsk | (15h 16m 08.64s , +73d 36m 52.0s) | C | 120 | 17.5 | 926 | 2026-02-12 18:03:34 | MASTER-Kislovodsk | (15h 16m 10.47s , +73d 36m 57.7s) | C | 120 | 17.6 | 1068 | 2026-02-12 18:05:56 | MASTER-Kislovodsk | (15h 16m 12.12s , +73d 37m 03.6s) | C | 120 | 17.7 | 1209 | 2026-02-12 18:08:16 | MASTER-Kislovodsk | (15h 16m 13.41s , +73d 37m 09.3s) | C | 120 | 17.4 | 1652 | 2026-02-12 18:16:09 | MASTER-Kislovodsk | (15h 10m 30.28s , +72d 55m 28.4s) | C | 60 | 17.0 | 1860 | 2026-02-12 18:19:38 | MASTER-Kislovodsk | (15h 30m 36.29s , +74d 48m 40.5s) | C | 60 | 17.3 | 2274 | 2026-02-12 18:26:31 | MASTER-Kislovodsk | (15h 03m 57.80s , +76d 45m 03.8s) | C | 60 | 17.0 | 2516 | 2026-02-12 18:30:34 | MASTER-Kislovodsk | (15h 52m 21.24s , +72d 54m 23.0s) | C | 60 | 17.3 | 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/43717. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41824] GRB 260212A: Fermi GBM Final Real-time Localization
by GCN Circulars 12 Feb '26

12 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43716 SUBJECT: GRB 260212A: Fermi GBM Final Real-time Localization DATE: 26/02/12 17:59:41 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 17:49:08 UT on 12 Feb 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260212A (trigger 792611353.21224 / 260212742). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 228.9, Dec = 74.1 (J2000 degrees, equivalent to J2000 15h 15m, 74d 05'), with a statistical uncertainty of 1.1 degrees. The angle from the Fermi LAT boresight is 127.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260212742/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260212742/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260212742/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43716. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41823] GRB 260211A: LAST optical upper limit
by GCN Circulars 12 Feb '26

12 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43715 SUBJECT: GRB 260211A: LAST optical upper limit DATE: 26/02/12 17:46:24 GMT FROM: Ruslan Konno at Weizmann Institute of Science <ruslankonno(a)gmail.com> R. Konno (WIS), S. Garrappa (WIS), E. A. Zimmerman (WIS), A. Horowicz (WIS), E. O. Ofek (WIS), S. Ben-Ami (WIS), D. Polishook (WIS), O. Yaron (WIS), S. Fainer (WIS), A. Krassilchtchikov (WIS), Y. M. Shani (WIS), E. Segre (WIS), A. Gal-Yam (WIS), and S. Spitzer (WIS) report on behalf of the LAST Collaboration. We report observations of GRB 260211A, detected by SVOM (Gotz et al., GCN 43705). Observations were conducted with the Large Array Survey Telescope (LAST; Ofek et al. 2023, PASP 135, 5001; Ben-Ami et al. 2023, PASP 135, 5002). We observed the field of GRB 260211A using 4 divergent telescopes (each with a 7.4 deg^2 FoV) in clear band (similar to the Gaia Bp band) over 18 sequential epochs. Each epoch consists of 20x20s exposures. We began observations at 2026-02-11 19:27:31 UTC (T-T0 = 178 s). We coadd a total of 220x20s exposure images and perform image subtraction using a reference image of the field. We do not detect any new optical source up to a limiting magnitude of 20.12 (AB) within the error region reported in Gotz et al., GCN 43705. LAST is a survey telescope array of the Weizmann Astrophysical Observatory (https://www.weizmann.ac.il/wao/) View this GCN Circular online at https://gcn.nasa.gov/circulars/43715. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41822] GRB 260210A: SVOM/GRM observation
by GCN Circulars 12 Feb '26

12 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43714 SUBJECT: GRB 260210A: SVOM/GRM observation DATE: 26/02/12 16:38:55 GMT FROM: guohx(a)ihep.ac.cn SVOM/GRM team: Hao-Xuan Guo, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Feliu Lacreu (IAP), Olivier GODET (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by GRB 260210A at 2026-02-10T11:27:37.300 (T0), which is also detected by KONUS-Wind, AstroSat CZTI (Arya et al., GCN #43686) and Glowbug (Cheung et al., GCN #43689). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multiple pulses with a T90 of 34.4 +8.8/-5.2 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb260210A.png In addition, the position of this burst, as determined by on-ground trigger (RA = 254, Dec = 19, Error = 57), is located at about 72 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. But this burst is still detected by ECLAIRs through the shield. With this localization, the time-averaged spectrum from T0-30 to T0+62 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.33 +0.15/-0.14 and the cutoff energy, parameterized as Epeak, is 182 +65/-36 keV. The event fluence (10-1000 keV) in this time interval is (1.67 +0.17/-0.15)E-05 erg/cm^2. The 1s peak spectrum, measured from T0+0.7 to T0+1.7 s, is also best fitted by a power law function with an exponential high-energy cutoff. The power law index is -0.74 +0.17/-0.16 and the cutoff energy, parameterized as Epeak, is 207 +33/-24 keV. The flux (10-1000 keV) in this time interval is (1.34 +0.11/-0.10)E-06 erg/cm^2/s. The localization of GRB 260210A in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb260210A_amati.png And the localization in the 'Yonetoku' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb260210A_yonetoku.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/GRM point of contact for this burst is: Hao-Xuan Guo (IHEP) (guohx(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/43714. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41821] Fermi GBM Sub-Threshold Detection of GRB 260211A
by GCN Circulars 12 Feb '26

12 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43713 SUBJECT: Fermi GBM Sub-Threshold Detection of GRB 260211A DATE: 26/02/12 14:47:00 GMT FROM: rhamburg(a)usra.edu R. Hamburg (USRA) reports on behalf of the Fermi-GBM Team: SVOM/ECLAIRs detected GRB 260211A on 2026-02-11 at 19:24:33 UTC (GCN 43705). There was no Fermi-GBM onboard trigger around this time. An automated, blind search for gamma-ray bursts below the onboard triggering threshold in Fermi-GBM identified no candidates. The GBM Targeted Search [1], the most sensitive coherent search for GRB-like signals in GBM, identified a transient starting 0.8 seconds after the ECLAIRs trigger time, most significantly on the 16 s timescale and with a false alarm rate of 4.3e-05 Hz. The Fermi-MET of this transient is 792530678.844 s. The Targeted Search localization is consistent with the ECLAIRs location. Additionally, the GBM Targeted Search transient was found with highest significance using a soft spectral template (i.e., Band function with Epeak = 70 keV, alpha = -1.9, beta = -3.7). [1] Goldstein et al. 2019 arXiv:1903.1259 View this GCN Circular online at https://gcn.nasa.gov/circulars/43713. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 41820] Konus-Wind detection of GRB 260207B
by GCN Circulars 12 Feb '26

12 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43712 SUBJECT: Konus-Wind detection of GRB 260207B DATE: 26/02/12 14:06:38 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The short-duration GRB with extended emission (EE) GRB 260207B (Fermi-GBM detection: Fermi GBM team, GCN 43629; Sonawane & Bala, GCN 43634; GECAM-B detection: Zao et al., GCN 43644; AstroSat-CZTI detection: Goyal et al., GCN 43680; IPN triangulation: Kozyrev et al., GCN 43691; GRID detection: Zeng et al., GCN 43710) triggered Konus-Wind at T0=47529.467 s UT (13:12:09.467). The burst light curve shows a short initial pulse, which starts at ~T0-40 ms and has a duration of ~220 ms. The initial pulse is followed by a weaker extended emission (EE), starting at ~T0+9 s, peaking at ~T0+43 s, and lasting up to ~T0+95 s. The emission in the initial pulse is seen up to ~2 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260207_T47529/ As observed by Konus-Wind, the initial pulse had the fluence of 2.66(-0.19,+0.20)x10^-6 erg/cm2, and the 16-ms peak flux, measured from T0+0.104 s, of 4.41(-0.54,+0.58)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the initial pulse (measured from T0 to T0+0.192 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.99(-0.08,+0.08) and Ep = 495(-60,+72) keV (chi2 = 44/43 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -3.1 (chi2 = 44/42 dof). The time-averaged spectrum of the EE (measured from T0+8.448 s to T0+73.984 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: with alpha = -1.67(-0.21,+0.24) and Ep = 44 (-19,+11) keV (chi2 = 93/98 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -3.0 (chi2 = 93/97 dof). From this spectrum, the total EE fluence is 5.02(-0.4,+0.4)x10^-6 erg/cm2, a factor of ~2 higher than that of the initial pulse. All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/43712. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0