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

[vsnet-grb-info 41809] Konus-Wind detection of GRB 260209B
by GCN Circulars 11 Feb '26

11 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43703 SUBJECT: Konus-Wind detection of GRB 260209B DATE: 26/02/11 19:06:19 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, hard-spectrum GRB 260209B triggered Konus-Wind (KW) at T0=66273.996 s UT (18:24:33.996). The burst consists of two bright, multi-peaked emission pulses and has a total duration of ~26 s. The emission is seen up to ~7 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260209_T66273/ As observed by Konus-Wind, the burst had the fluence of (3.44 ± 0.35)x10^-5 erg/cm^2 and the 64-ms peak energy flux, measured from T0 + 2.880 s, of (3.70 ± 0.28)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum of the burst (measured from T0 to T0+24.832 s) is best fitted in the 20 keV - 15 MeV range by a power law with exponential cutoff (CPL) model dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.34 (-0.04, + 0.05) and Ep = 1340(-257,+343) keV, chi^2 = 112/98 dof. Fitting this spectrum by a Band GRB function yields the same values of alpha and Ep, and only an upper limit on the high energy photon index beta of -2.7 The spectrum near the peak count rate (measured from T0 to T0+8.448 s) is best fitted in the 20 keV - 15 MeV range by a CPL model with alpha = -1.25 (-0.3, + 0.04)and Ep = 1704(-233,+277) keV, chi^2 = 97/85 dof. Fitting this spectrum by a Band function yields the same values of alpha and Ep, and only an upper limit on the high energy photon index beta of -2.8 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/43703. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41808] GRB 260228A: Swift UVOT detection
by GCN Circulars 11 Feb '26

11 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43702 SUBJECT: GRB 260228A: Swift UVOT detection DATE: 26/02/11 17:42:26 GMT FROM: Paul Kuin at MSSL <npkuin(a)gmail.com> Paul Kuin (MSSL/UCL) and Brad Cenko (NSA/GSFC) reports on behalf of the Swift/UVOT team: The Swift/UVOT began observations of the Fermi-detected GRB 260208A 35.4 ks after the Fermi Trigger (Fermi GBM team, GCN Circ. 43635; Longo et al., GCN Circ. 43645). We detect the afterglow at the position given by Podesta et al., GCN Circ. 43640. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 35662.9 41566.1 1208 20.84 +/-0.10 €€€€€€€€€€€€ white 46325.8 47072.6 735 21.45 +/-0.21 u 35131.3 40857.7 1208 20.34 +/-0.14 €€€€€€€€€€€€ u 45572.3 46319.1 735 20.12 +/-0.15 y. v 36195.1 47089.2 938 20.01 +/-0.32 View this GCN Circular online at https://gcn.nasa.gov/circulars/43702. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41807] Konus-Wind detection of GRB 260127B
by GCN Circulars 11 Feb '26

11 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43701 SUBJECT: Konus-Wind detection of GRB 260127B DATE: 26/02/11 17:39:39 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(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 260127B (Fermi-GBM detection: The Fermi GBM team, GCN 43533; Trigg, GCN 43573; IPN triangulation: Ridnaia et al., GCN 43559; AstroSat-CZTI detection: ,GCN 43576; GECAM-B observation: Ren et al., GCN 43597; Insight-HXMT/HE detection: Ren et al., GCN 43598) triggered Konus-Wind at T0=72154.163 s UT (20:02:34.163). The burst light curve shows a multipeaked structure, which starts at ~T0-0.1 s and has a total duration of ~0.3 s. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260127_T72154/ As observed by Konus-Wind, the burst had a fluence of 2.09(-0.27,+0.38)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0+0.062 s, of 1.80(-0.40,+0.51)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+0.128 s) is best fit in the 20 keV - 1.3 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.21(-0.27,+0.31) and Ep = 796(-151,+261) keV (chi2 = 24/25 dof). 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/43701. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41806] EP260209a: COLIBRÍ optical upper limit
by GCN Circulars 11 Feb '26

11 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43700 SUBJECT: EP260209a: COLIBRÍ optical upper limit DATE: 26/02/11 16:49:52 GMT FROM: Jean-Luc Atteia at IRAP <jean-luc.atteia(a)irap.omp.eu> Jean-Luc Atteia (IRAP), Fredd Sánchez Álvarez (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Edilberto Aguilar-Ruiz (UNAM), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), 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), Noémie Globus (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), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM) report: We imaged the field of the EP transient EP260209a (Zhang et al., GCN Circ. 43693) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-02-11 12:43 to 13:02 UTC ( 47.0 to 47.4 hours after the trigger) and obtained 960 seconds 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. In the stacked image, we do not detect any new source at the FXT source position (Zhang et al., GCN Circ. 43693) down to the following 5-sigma limit: r > 20.4, z > 18.8. These limits are compatible with those of LCO (Corcoran et al. GCN Circ. 43698) 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/43700. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41805] Fermi GRB 260210C: Global MASTER-Net observations report
by GCN Circulars 11 Feb '26

11 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43699 SUBJECT: Fermi GRB 260210C: Global MASTER-Net observations report DATE: 26/02/11 16:45:47 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 260210C ( Fermi GBM team, GCN 43690) errorbox 71030 sec after notice time and 71220 sec after trigger time at 2026-02-11 15:36:42 UT, with upper limit up to 17.7 mag. Observations started at twilight. The observations began at zenith distance = 67 deg. The sun altitude is -11.6 deg. The galactic latitude b = -30 deg., longitude l = 87 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3128802 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 71250 | 2026-02-11 15:36:42 | MASTER-Kislovodsk | (22h 34m 34.78s , +22d 28m 07.7s) | C | 60 | 15.8 | 71357 | 2026-02-11 15:38:29 | MASTER-Kislovodsk | (22h 21m 37.65s , +22d 26m 29.0s) | C | 60 | 15.9 | 71964 | 2026-02-11 15:48:36 | MASTER-Kislovodsk | (22h 27m 29.52s , +24d 20m 43.1s) | C | 60 | 16.7 | 72653 | 2026-02-11 16:00:05 | MASTER-Kislovodsk | (22h 30m 03.09s , +20d 30m 18.0s) | C | 60 | 17.4 | 72765 | 2026-02-11 16:01:57 | MASTER-Kislovodsk | (22h 14m 25.78s , +24d 18m 57.0s) | C | 60 | 17.5 | 72867 | 2026-02-11 16:03:39 | MASTER-Kislovodsk | (22h 21m 40.66s , +26d 11m 29.9s) | C | 60 | 17.7 | 72975 | 2026-02-11 16:05:27 | MASTER-Kislovodsk | (22h 47m 29.43s , +22d 24m 59.2s) | C | 60 | 17.3 | 73080 | 2026-02-11 16:07:12 | MASTER-Kislovodsk | (22h 17m 16.21s , +20d 30m 58.2s) | C | 60 | 16.7 | 73648 | 2026-02-11 16:16:40 | MASTER-Kislovodsk | (22h 42m 55.62s , +20d 31m 49.9s) | C | 60 | 17.3 | 74157 | 2026-02-11 16:25:09 | MASTER-Kislovodsk | (22h 53m 48.41s , +24d 19m 15.5s) | C | 60 | 16.9 | 74286 | 2026-02-11 16:27:18 | MASTER-Kislovodsk | (22h 44m 21.71s , +28d 05m 30.3s) | C | 60 | 16.8 | 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/43699. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41804] EP260209a: LCO optical upper limits
by GCN Circulars 11 Feb '26

11 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43698 SUBJECT: EP260209a: LCO optical upper limits DATE: 26/02/11 16:41:01 GMT FROM: Gregory Corcoran at University College Dublin <gregory.corcoran(a)ucdconnect.ie> G. Corcoran (UCD) and J. A. Quirola-Vasquez (Radboud) report on behalf of a larger collaboration: We observed the field of the fast X-ray transient EP260209a (Zhang et al., GCN 43693) using the LCO 1m telescope located at the McDonald Observatory (Texas, USA) equipped with the SINISTRO instrument. Our observations consisted of a sequence of 4x300 s exposures in the SDSS r-band starting on 2026-02-11 at 12:22:56 UT (~1.44 days after the WXT trigger). We do not detect any sources within the EP/FXT uncertainty region (Zhang et al., GCN 43693). From the stacked image, we obtain the following 3-sigma upper limiting magnitude:  r > 22.5 This limit is in the AB system, calibrated using nearby stars from the Pan-STARRS catalog, and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43698. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41803] EP260210a: Global MASTER-Net observations report
by GCN Circulars 11 Feb '26

11 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43697 SUBJECT: EP260210a: Global MASTER-Net observations report DATE: 26/02/11 15:54:23 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 EP260210a ( EP Team et al., GCN 43681) errorbox 1 days 8970 sec after notice time and 1 days 16089 sec after trigger time at 2026-02-11 14:49:07 UT, with upper limit up to 20.9 mag. The observations began at zenith distance = 41 deg. The sun altitude is -42.1 deg. The galactic latitude b = 65 deg., longitude l = 162 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3130129 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 7568 | 2026-02-10 12:25:35 | MASTER- | (11h 18m 01.50s , +46d 01m 48.3s) | C | 180 | 20.1 | 7568 | 2026-02-10 12:25:35 | MASTER- | (11h 19m 42.26s , +45d 29m 04.1s) | C | 180 | 19.9 | 7757 | 2026-02-10 12:28:45 | MASTER- | (11h 18m 02.83s , +46d 02m 53.1s) | C | 180 | 20.0 | 7757 | 2026-02-10 12:28:45 | MASTER- | (11h 19m 43.41s , +45d 30m 08.6s) | C | 180 | 19.8 | 7947 | 2026-02-10 12:31:54 | MASTER- | (11h 18m 09.32s , +46d 01m 59.2s) | C | 180 | 19.9 | 7947 | 2026-02-10 12:31:54 | MASTER- | (11h 19m 49.66s , +45d 29m 14.2s) | C | 180 | 19.7 | 8137 | 2026-02-10 12:35:04 | MASTER- | (11h 18m 03.97s , +46d 01m 06.6s) | C | 180 | 19.7 | 8137 | 2026-02-10 12:35:04 | MASTER- | (11h 19m 44.15s , +45d 28m 20.7s) | C | 180 | 19.5 | 8327 | 2026-02-10 12:38:14 | MASTER- | (11h 19m 50.14s , +45d 28m 55.2s) | C | 180 | 18.1 | 9693 | 2026-02-10 13:01:01 | MASTER- | (11h 18m 06.50s , +46d 04m 07.7s) | C | 180 | 19.5 | 9693 | 2026-02-10 13:01:01 | MASTER- | (11h 19m 42.80s , +45d 31m 23.3s) | C | 180 | 19.3 | 102519 | 2026-02-11 14:49:07 | MASTER-Tunka | (11h 17m 51.29s , +45d 05m 25.7s) | C | 60 | 20.1 | 102519 | 2026-02-11 14:49:07 | MASTER-Tunka | (11h 17m 17.48s , +45d 11m 57.6s) | C | 60 | 20.1 | 102579 | 2026-02-11 14:49:07 | MASTER-Tunka | (11h 17m 17.48s , +45d 11m 57.6s) | C | 180 | 20.8 | Coadd 102593 | 2026-02-11 14:50:21 | MASTER-Tunka | (11h 17m 48.72s , +45d 07m 01.6s) | C | 60 | 20.1 | 102593 | 2026-02-11 14:50:21 | MASTER-Tunka | (11h 17m 14.82s , +45d 13m 33.5s) | C | 60 | 20.1 | 102675 | 2026-02-11 14:51:42 | MASTER-Tunka | (11h 17m 14.77s , +45d 11m 48.3s) | C | 60 | 20.2 | 102675 | 2026-02-11 14:51:42 | MASTER-Tunka | (11h 17m 48.77s , +45d 05m 16.6s) | C | 60 | 20.1 | 102777 | 2026-02-11 14:52:55 | MASTER-Tunka | (11h 17m 18.23s , +45d 13m 40.4s) | C | 120 | 20.3 | 102897 | 2026-02-11 14:52:55 | MASTER-Tunka | (11h 17m 18.23s , +45d 13m 40.3s) | C | 360 | 20.9 | Coadd 102777 | 2026-02-11 14:52:55 | MASTER-Tunka | (11h 17m 52.48s , +45d 07m 09.3s) | C | 120 | 20.3 | 102911 | 2026-02-11 14:55:08 | MASTER-Tunka | (11h 17m 11.60s , +45d 12m 39.5s) | C | 120 | 20.4 | 102911 | 2026-02-11 14:55:08 | MASTER-Tunka | (11h 17m 46.09s , +45d 06m 09.1s) | C | 120 | 20.4 | 103052 | 2026-02-11 14:57:30 | MASTER-Tunka | (11h 17m 46.28s , +45d 07m 08.1s) | C | 120 | 20.4 | 103052 | 2026-02-11 14:57:30 | MASTER-Tunka | (11h 17m 11.47s , +45d 13m 37.9s) | C | 120 | 20.4 | 103185 | 2026-02-11 14:59:43 | MASTER-Tunka | (11h 17m 52.89s , +45d 06m 06.4s) | C | 120 | 20.3 | 103185 | 2026-02-11 14:59:43 | MASTER-Tunka | (11h 17m 17.88s , +45d 12m 35.6s) | C | 120 | 20.4 | 103349 | 2026-02-11 15:02:26 | MASTER-Tunka | (11h 16m 48.88s , +46d 09m 10.4s) | C | 120 | 20.4 | 103349 | 2026-02-11 15:02:26 | MASTER-Tunka | (11h 17m 28.36s , +46d 01m 15.6s) | C | 120 | 20.3 | 103469 | 2026-02-11 15:02:26 | MASTER-Tunka | (11h 17m 28.35s , +46d 01m 15.6s) | C | 360 | 20.8 | Coadd 103485 | 2026-02-11 15:04:42 | MASTER-Tunka | (11h 16m 55.90s , +46d 09m 20.0s) | C | 120 | 20.4 | 103485 | 2026-02-11 15:04:42 | MASTER-Tunka | (11h 17m 35.59s , +46d 01m 25.7s) | C | 120 | 20.4 | 103618 | 2026-02-11 15:06:56 | MASTER-Tunka | (11h 16m 51.63s , +46d 10m 48.7s) | C | 120 | 20.4 | 103618 | 2026-02-11 15:06:56 | MASTER-Tunka | (11h 17m 31.57s , +46d 02m 54.6s) | C | 120 | 20.3 | 103751 | 2026-02-11 15:09:09 | MASTER-Tunka | (11h 16m 51.33s , +46d 09m 05.5s) | C | 120 | 20.3 | 103751 | 2026-02-11 15:09:09 | MASTER-Tunka | (11h 17m 31.48s , +46d 01m 11.8s) | C | 120 | 20.3 | 103871 | 2026-02-11 15:09:09 | MASTER-Tunka | (11h 17m 31.47s , +46d 01m 11.8s) | C | 360 | 20.7 | Coadd 103885 | 2026-02-11 15:11:23 | MASTER-Tunka | (11h 17m 34.65s , +46d 02m 45.1s) | C | 120 | 20.3 | 103885 | 2026-02-11 15:11:23 | MASTER-Tunka | (11h 16m 54.22s , +46d 10m 39.3s) | C | 120 | 20.3 | 104023 | 2026-02-11 15:13:41 | MASTER-Tunka | (11h 17m 29.15s , +46d 02m 05.1s) | C | 120 | 20.3 | 104023 | 2026-02-11 15:13:41 | MASTER-Tunka | (11h 16m 48.47s , +46d 09m 59.3s) | C | 120 | 20.3 | 104159 | 2026-02-11 15:15:56 | MASTER-Tunka | (11h 17m 27.69s , +46d 03m 03.6s) | C | 120 | 20.3 | 104279 | 2026-02-11 15:15:56 | MASTER-Tunka | (11h 17m 27.68s , +46d 03m 03.7s) | C | 360 | 20.7 | Coadd 104159 | 2026-02-11 15:15:56 | MASTER-Tunka | (11h 16m 46.62s , +46d 10m 57.7s) | C | 120 | 20.3 | 104292 | 2026-02-11 15:18:10 | MASTER-Tunka | (11h 16m 53.54s , +46d 09m 55.8s) | C | 120 | 20.3 | 104292 | 2026-02-11 15:18:10 | MASTER-Tunka | (11h 17m 34.89s , +46d 02m 02.3s) | C | 120 | 20.2 | 104425 | 2026-02-11 15:20:23 | MASTER-Tunka | (11h 16m 46.28s , +46d 08m 53.8s) | C | 120 | 20.3 | 104425 | 2026-02-11 15:20:23 | MASTER-Tunka | (11h 17m 27.96s , +46d 01m 00.0s) | C | 120 | 20.3 | 104559 | 2026-02-11 15:22:36 | MASTER-Tunka | (11h 16m 53.19s , +46d 09m 18.6s) | C | 120 | 20.3 | 104559 | 2026-02-11 15:22:36 | MASTER-Tunka | (11h 17m 35.15s , +46d 01m 24.7s) | C | 120 | 20.3 | 104679 | 2026-02-11 15:22:36 | MASTER-Tunka | (11h 17m 35.15s , +46d 01m 24.6s) | C | 360 | 20.7 | Coadd 104693 | 2026-02-11 15:24:50 | MASTER-Tunka | (11h 16m 48.89s , +46d 10m 36.4s) | C | 120 | 20.2 | 104693 | 2026-02-11 15:24:50 | MASTER-Tunka | (11h 17m 31.14s , +46d 02m 42.6s) | C | 120 | 20.2 | 104826 | 2026-02-11 15:27:04 | MASTER-Tunka | (11h 16m 48.61s , +46d 08m 57.8s) | C | 120 | 20.2 | 104826 | 2026-02-11 15:27:04 | MASTER-Tunka | (11h 17m 31.07s , +46d 01m 04.0s) | C | 120 | 20.0 | 104964 | 2026-02-11 15:29:21 | MASTER-Tunka | (11h 16m 51.20s , +46d 10m 29.3s) | C | 120 | 20.2 | 104964 | 2026-02-11 15:29:21 | MASTER-Tunka | (11h 17m 33.89s , +46d 02m 34.8s) | C | 120 | 20.0 | 105084 | 2026-02-11 15:29:21 | MASTER-Tunka | (11h 17m 33.89s , +46d 02m 34.8s) | C | 360 | 20.6 | Coadd 105098 | 2026-02-11 15:31:35 | MASTER-Tunka | (11h 16m 44.36s , +46d 09m 44.7s) | C | 120 | 20.2 | 105098 | 2026-02-11 15:31:35 | MASTER-Tunka | (11h 17m 27.28s , +46d 01m 49.9s) | C | 120 | 20.2 | 105231 | 2026-02-11 15:33:48 | MASTER-Tunka | (11h 16m 43.65s , +46d 10m 43.2s) | C | 120 | 20.2 | 105231 | 2026-02-11 15:33:48 | MASTER-Tunka | (11h 17m 26.90s , +46d 02m 48.1s) | C | 120 | 20.2 | 105363 | 2026-02-11 15:36:01 | MASTER-Tunka | (11h 16m 49.86s , +46d 09m 40.6s) | C | 120 | 20.2 | 105363 | 2026-02-11 15:36:01 | MASTER-Tunka | (11h 17m 33.35s , +46d 01m 46.0s) | C | 120 | 20.2 | 105513 | 2026-02-11 15:36:01 | MASTER-Tunka | (11h 17m 33.35s , +46d 01m 46.1s) | C | 420 | 20.6 | Coadd 105496 | 2026-02-11 15:38:13 | MASTER-Tunka | (11h 16m 44.46s , +46d 08m 38.1s) | C | 120 | 19.8 | 105496 | 2026-02-11 15:38:13 | MASTER-Tunka | (11h 17m 28.25s , +46d 00m 43.9s) | C | 120 | 19.9 | 105659 | 2026-02-11 15:40:27 | MASTER-Tunka | (11h 16m 48.73s , +46d 08m 57.2s) | C | 180 | 20.1 | 105659 | 2026-02-11 15:40:27 | MASTER-Tunka | (11h 17m 32.92s , +46d 01m 02.1s) | C | 180 | 20.1 | 105853 | 2026-02-11 15:43:40 | MASTER-Tunka | (11h 16m 46.04s , +46d 10m 05.2s) | C | 180 | 20.1 | 105853 | 2026-02-11 15:43:40 | MASTER-Tunka | (11h 17m 30.80s , +46d 02m 10.3s) | C | 180 | 20.1 | 106045 | 2026-02-11 15:46:53 | MASTER-Tunka | (11h 17m 30.87s , +46d 00m 58.4s) | C | 180 | 20.0 | 106045 | 2026-02-11 15:46:53 | MASTER-Tunka | (11h 16m 45.59s , +46d 08m 52.7s) | C | 180 | 20.0 | 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/43697. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41802] EP260210a: refined analysis of the EP-FXT observation
by GCN Circulars 11 Feb '26

11 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43696 SUBJECT: EP260210a: refined analysis of the EP-FXT observation DATE: 26/02/11 14:20:01 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Z. H. Yang, R. Shi (PMO), Q. C. Zhao (IHEP), G. Y. Zhao (SYSU), Y. J. Zhang (THU) and Z. X. Ling (NAOC) on behalf of the Einstein Probe (EP) team: The fast X-ray transient EP260210a was detected by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Shi et al., GCN 43681). The refined analysis of the WXT data shows that the event started at T0=2026-02-10T10:20:58.53 (UTC), and lasted for approximately 220 seconds. The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 1.6×10^20 cm^-2, and a photon index of 1.57 (-0.4/+0.4). The derived average unabsorbed 0.5-4 keV flux is 1.5 (-0.3/+0.4) × 10^(-10) erg/s/cm^2. The Follow-up X-ray Telescope (FXT) on board EP autonomously observed this source a few minutes after the on board trigger. The FXT observation started at 2026-02-10T10:24:57 (UTC, T0+238 s). The effective exposure time of the observation is around 5 ks. On-ground analysis of the FXT data found an uncatalogued source at R.A. = 169.8314, DEC = 45.3949 (J2000) with an uncertainty of 10 arcsec in radius (90% C.L. statistical and systematic). The average 0.5-10 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 1.6 × 10^20 cm^-2, and a photon index of 2.7 (-0.1/+0.1). The derived average unabsorbed 0.5-10 keV flux is 6.4 (-1.0/+1.0) ×10^(-12) erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. Further FXT follow-up observations have been arranged. 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/43696. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41801] EP260209a: Global MASTER-Net observations report
by GCN Circulars 11 Feb '26

11 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43695 SUBJECT: EP260209a: Global MASTER-Net observations report DATE: 26/02/11 12:45:25 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 EP260209a ( EP Team et al., GCN 43693) errorbox 105 sec after notice time and 1 days 79337 sec after trigger time at 2026-02-11 11:46:23 UT, with upper limit up to 19.1 mag. Observations started at twilight. The observations began at zenith distance = 73 deg. The sun altitude is -14.9 deg. The galactic latitude b = 61 deg., longitude l = 203 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3129906 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 165768 | 2026-02-11 11:46:23 | MASTER-Tunka | (10h 36m 50.32s , +28d 07m 55.2s) | C | 60 | 18.9 | 165768 | 2026-02-11 11:46:23 | MASTER-Tunka | (10h 37m 06.41s , +28d 01m 58.3s) | C | 60 | 19.1 | 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/43695. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41800] GRB 260208A: LCO detection of the optical counterpart
by GCN Circulars 11 Feb '26

11 Feb '26

TITLE: GCN CIRCULAR NUMBER: 43694 SUBJECT: GRB 260208A: LCO detection of the optical counterpart DATE: 26/02/11 12:33:24 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf(a)iac.es> I. Pérez-Fournon (IAC and ULL), F. Poidevin (IAC and ULL), D. Cano-Morales, A.E. Hernández-Díaz, I. Correa-Plasencia, E. Lekaroz-Urriza, M. Quintana-Ansaldo (all ULL), and A. López-Oramas (IAC and ULL) Following the detection of the bright and long GRB 260208A detected by Fermi GMB (Fermi GBM Team, GCN #43635; Mukherjee and Meegan, GCN #43673), Fermi LAT (Longo et al., GCN #43645), Swift-XRT (Dichiara et al., GCN #43652; Longo et al., GCN #43643), GECAM-B (Luo et al., GCN #43658), NuSTAR (Waratkar et al., GCN #43674), and Glowbug (Cheung et al., GCN #43675), we observed the field with one of the three Las Cumbres Observatory (LCO) 1-m telescopes located at the LCO node at Cerro Tololo Inter-American Observatory (CTIO), Chile. The observation, a single exposure of 300 sec in the SDSS r' filter, started on 2026-02-09 at 07:48:36 UT, about 26.69 hours after the Fermi trigger. The optical counterpart AT 2026ciw (MASTER OT J133855.62+334806.9, GOTO26aob, ZTF26aafswob) first detected by Podesta et al. (MASTER, GCN #43640) and Wortley et al. (GOTO, GCN #43641) is detected in our image with an AB magnitude of r' = 20.92 +/- 0.17, calibrated against PanSTARRS-1 DR2 stars and not corrected for Galactic extinction. This result is consistent with the late evolution of the optical afterglow of this redshfit z = 2.36 GRB (Dimple et al., GCN #43662). Optical detections have been reported by Podesta et al. (GCN #43640), Wortley et al. (GCN #43641), Ma et al. (GCN #43655), Ahumada et al. (GCN #43657), Dimple et al. (GCN #43661), Dimple et al. (GCN #43662), Magnani et al. (GCN #43664), Gupta et al. (GCN #43665), Volnova et al. (GCN #43666), and Bochenek et al. (GCN #43676). This work makes use of observations from the Las Cumbres Observatory global telescope network (LCO program IAC2026A-011, SGLF and Superluminous Supernovae surveys). This work made use of the Astro-COLIBRI platform (P. Reichherzer et al. 2021, ApJS, 256, 5). View this GCN Circular online at https://gcn.nasa.gov/circulars/43694. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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