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

[vsnet-grb-info 41640] GRB 260127B: GOTO candidate optical counterpart
by GCN Circulars 28 Jan '26

28 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43538 SUBJECT: GRB 260127B: GOTO candidate optical counterpart DATE: 26/01/28 10:22:31 GMT FROM: d.s.oneill(a)bham.ac.uk D. O’Neill, B. P. Gompertz, G. Ramsay, M. Kennedy, D. Steeghs, J. Lyman, R. Starling, K. Ackley, M. Dyer, K. Ulaczyk, D. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. Kotak, R. Breton, J. Casares, L. Nuttall, B. Godson, T. Killestein, A. Kumar, M. Pursiainen report 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 short GRB 260127B (Fermi GBM Team, GCN 43533). Observations covering the localisation area began at 2026-01-28 00:20:53 UT (+4.31h post trigger) and continued through to 2026-01-28 05:10:59 (+9.14h post trigger). 141 images were taken, across 9 unique pointings, covering 242.7 square degrees within the 90% localisation contour. ~61.4% of the total 2D localisation probability was covered, with an average 5-sigma depth of 20.2 mag. Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations. Source candidates were initially filtered using a classifier (Killestein et al. 2021) and cross-matched against a variety of contextual and minor planet catalogs. Human vetting was carried out in real time on any candidates that passed the above checks. We identify one candidate optical counterpart, GOTO26aih (AT2026bnn), within the 90% probability contour at coordinates RA = 12:49:52.73, Dec = +66:44:58.87, equivalent to RA = 192.469711, Dec =66.74969 degrees. This position lies on the 84th percentile probability contour of the Fermi/GBM localisation map. The source was initially detected with L = 19.15 ± 0.14 AB mag (t0+5.66h), before fading to L = 19.82 ± 0.11 mag (t0+7.91h). The measured rate of decay is t^-1.66 ± 0.97. We find no evidence of the source prior to the GRB trigger time in the most recent GOTO observations taken at 2026-01-20 06:01:17 (t0-7.6 days) down to a 5-sigma depth of >20.8 AB mag. We also find no evidence for pre-GRB emission in the ZTF observations provided by the Lasair broker (Smith et al. 2019), or the ATLAS forced photometry server (Shingles et al. 2021). GOTO26aih/AT2026bnn is spatially coincident with the galaxy SDSS J124952.79+664500.4, offset by 1.5” from the core. This galaxy has a measured spectroscopic redshift of z = 0.12 (DESI Collaboration, 2025). A summary of our observations is presented below. +------------------------------------------------------------+ | Observation time (UT) | t-t0 | filter | mag | +------------------------------------------------------------+ | 2026-01-20 06:01:17 | -181.42h | L | >20.8 | | 2026-01-28 01:01:13 | +5.66h | L | 19.15 ± 0.14 | | 2026-01-28 02:01:23 | +6.78h | L | 19.79 ± 0.14 | | 2026-01-28 03:01:22 | +7.91h | L | 19.82 ± 0.11 | +-------------------------------------------------------------+ Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and not corrected for Galactic extinction. 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/43538. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41639] GRB 260127A: SVOM/C-GFT optical observations
by GCN Circulars 28 Jan '26

28 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43537 SUBJECT: GRB 260127A: SVOM/C-GFT optical observations DATE: 26/01/28 04:44:46 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> C. Wu (NAOC), Z. Kang (CHO), L.P. Xin, X.H. Han, P.P. Zhang, X.M. Lu (NAOC), Z.W. Li, Y. Lv (CHO), R.S. Zhang, Y.J. Xiao, Y.L. Qiu, J. Wang, J.S. Deng, L. Huang, J.Y. Wei (NAOC) report on behalf of the SVOM/C-GFT team: We observed the field of GRB 260127A detected by Fermi/GBM (Fermi GBM team, GCN 43528) and Swift/BAT (Klingler et al., GCN 43529) with LATIOS on SVOM/C-GFT. Observations started at 2026-01-27T19:07:40 UTC, ~76.55 min after the trigger. The optical counterpart (Saccardiet et al., GCN 43530), consistent with XRT position (Evans et al., GCN 43532; Osborne et al., GCN 43535), was detected in our stacked i-band image. The magnitude is: | Mid_t-T0(hr) | exposure time (s) | band | mag (AB) | mag_err| |--------------|-------------------|------|----------|--------| | 2.24 | 30x90s | i | 20.37 | 0.20 | Our detection is deeper than the upper limit reported by Lipunov et al. (GCN 43532). The photometry was calibrated against nearby stars from UCAC4 catalog and no correction for Galactic dust extinction was applied. We thank the observation assistants Yin-Huai Hao Chun-Lei Guo at Jilin observatory for their excellent support. The Chinese Ground Follow-up Telescope (C-GFT) for the SVOM mission is located at Jilin Station, Changchun Observatory, National Astronomical Observatories, CAS. It features two instruments: (1) CATCH at the Cassegrain focus with a 21 arcsec x 21 arcsec FOV for simultaneous g/r/i-band imaging, and (2) LATIOS, a 4k x 4k CMOS camera at the prime focus with a 1.28 deg x 1.28 deg FOV that images in g, r, and i bands via filter switching. View this GCN Circular online at https://gcn.nasa.gov/circulars/43537. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41638] GRB 260127A: SVOM/C-GFT optical observations
by GCN Circulars 28 Jan '26

28 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43537 SUBJECT: GRB 260127A: SVOM/C-GFT optical observations DATE: 26/01/28 04:44:46 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> C. Wu (NAOC), Z. Kang (CHO), L.P. Xin, X.H. Han, P.P. Zhang, X.M. Lu (NAOC), Z.W. Li, Y. Lv (CHO), R.S. Zhang, Y.J. Xiao, Y.L. Qiu, J. Wang, J.S. Deng, L. Huang, J.Y. Wei (NAOC) report on behalf of the SVOM/C-GFT team: We observed the field of GRB 260127A detected by Fermi/GBM (Fermi GBM team, GCN 43528) and Swift/BAT (Klingler et al., GCN 43529) with LATIOS on SVOM/C-GFT. Observations started at 2026-01-27T19:07:40 UTC, ~76.55 min after the trigger. The optical counterpart (Saccardiet et al., GCN 43530), consistent with XRT position (Evans et al., GCN 43532; Osborne et al., GCN 43535), was detected in our stacked i-band image. The magnitude is: | Mid_t-T0(hr) | exposure time (s) | band | mag (AB) | mag_err| |--------------|-------------------|------|----------|--------| | 2.24 | 30x90s | i | 20.37 | 0.20 | Our detection is deeper than the upper limit reported by Lipunov et al. (GCN 43532). The photometry was calibrated against nearby stars from UCAC4 catalog and no correction for Galactic dust extinction was applied. We thank the observation assistants Yin-Huai Hao Chun-Lei Guo at Jilin observatory for their excellent support. The Chinese Ground Follow-up Telescope (C-GFT) for the SVOM mission is located at Jilin Station, Changchun Observatory, National Astronomical Observatories, CAS. It features two instruments: (1) CATCH at the Cassegrain focus with a 21 arcsec x 21 arcsec FOV for simultaneous g/r/i-band imaging, and (2) LATIOS, a 4k x 4k CMOS camera at the prime focus with a 1.28 deg x 1.28 deg FOV that images in g, r, and i bands via filter switching. View this GCN Circular online at https://gcn.nasa.gov/circulars/43537. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41637] GRB 260127A: SVOM/C-GFT optical observations
by GCN Circulars 28 Jan '26

28 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43537 SUBJECT: GRB 260127A: SVOM/C-GFT optical observations DATE: 26/01/28 04:44:46 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> C. Wu (NAOC), Z. Kang (CHO), L.P. Xin, X.H. Han, P.P. Zhang, X.M. Lu (NAOC), Z.W. Li, Y. Lv (CHO), R.S. Zhang, Y.J. Xiao, Y.L. Qiu, J. Wang, J.S. Deng, L. Huang, J.Y. Wei (NAOC) report on behalf of the SVOM/C-GFT team: We observed the field of GRB 260127A detected by Fermi/GBM (Fermi GBM team, GCN 43528) and Swift/BAT (Klingler et al., GCN 43529) with LATIOS on SVOM/C-GFT. Observations started at 2026-01-27T19:07:40 UTC, ~76.55 min after the trigger. The optical counterpart (Saccardiet et al., GCN 43530), consistent with XRT position (Evans et al., GCN 43532; Osborne et al., GCN 43535), was detected in our stacked i-band image. The magnitude is: | Mid_t-T0(hr) | exposure time (s) | band | mag (AB) | mag_err| |--------------|-------------------|------|----------|--------| | 2.24 | 30x90s | i | 20.37 | 0.20 | Our detection is deeper than the upper limit reported by Lipunov et al. (GCN 43532). The photometry was calibrated against nearby stars from UCAC4 catalog and no correction for Galactic dust extinction was applied. We thank the observation assistants Yin-Huai Hao Chun-Lei Guo at Jilin observatory for their excellent support. The Chinese Ground Follow-up Telescope (C-GFT) for the SVOM mission is located at Jilin Station, Changchun Observatory, National Astronomical Observatories, CAS. It features two instruments: (1) CATCH at the Cassegrain focus with a 21 arcsec x 21 arcsec FOV for simultaneous g/r/i-band imaging, and (2) LATIOS, a 4k x 4k CMOS camera at the prime focus with a 1.28 deg x 1.28 deg FOV that images in g, r, and i bands via filter switching. View this GCN Circular online at https://gcn.nasa.gov/circulars/43537. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41636] The EP-WXT trigger 01709253145 is likely a flaring star
by GCN Circulars 28 Jan '26

28 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43536 SUBJECT: The EP-WXT trigger 01709253145 is likely a flaring star DATE: 26/01/28 03:45:30 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> S.Y. Fu (HUST), D.F. Hu (PMO, CAS), J. Yang (ZZU), Y. Liu (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709253145 at the time of 2026-01-28T03:17:37 is likely a stellar flare associated with CD-37 6436. The estimated flux of the flare is around 6x10^-11 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 5.6x10^32 erg/s. 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/43536. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41635] GRB 260127A: Enhanced Swift-XRT position
by GCN Circulars 27 Jan '26

27 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43535 SUBJECT: GRB 260127A: Enhanced Swift-XRT position DATE: 26/01/27 21:35:45 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 1612 s of XRT Photon Counting mode data and 2 UVOT images for GRB 260127A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 231.87939, +6.76215 which is equivalent to: RA (J2000): 15h 27m 31.05s Dec (J2000): +06d 45' 43.7" with an uncertainty of 2.1 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at https://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43535. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41634] Fermi GRB 260127B: Global MASTER-Net observations report
by GCN Circulars 27 Jan '26

27 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43534 SUBJECT: Fermi GRB 260127B: Global MASTER-Net observations report DATE: 26/01/27 21:30:30 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) started inspect of the Fermi GRB 260127B ( Fermi GBM team, GCN 43533) errorbox 2657 sec after notice time and 2678 sec after trigger time at 2026-01-27 20:47:11 UT, with upper limit up to 19.7 mag. The observations began at zenith distance = 7 deg. The sun altitude is -37.8 deg. The galactic latitude b = 60 deg., longitude l = 125 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3117123 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 2709 | 2026-01-27 20:47:11 | MASTER-Tunka | (12h 37m 21.08s , +57d 00m 17.6s) | C | 60 | 19.5 | 2822 | 2026-01-27 20:49:04 | MASTER-Tunka | (12h 51m 46.69s , +57d 02m 10.2s) | C | 60 | 19.7 | 2897 | 2026-01-27 20:50:19 | MASTER-Tunka | (12h 19m 40.16s , +58d 55m 09.9s) | C | 60 | 19.7 | 2970 | 2026-01-27 20:51:32 | MASTER-Tunka | (12h 34m 49.83s , +58d 54m 52.1s) | C | 60 | 19.7 | 3049 | 2026-01-27 20:52:51 | MASTER-Tunka | (12h 27m 48.95s , +55d 06m 33.8s) | C | 60 | 19.7 | 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/43534. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41633] GRB 260127B: Fermi GBM Final Real-time Localization
by GCN Circulars 27 Jan '26

27 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43533 SUBJECT: GRB 260127B: Fermi GBM Final Real-time Localization DATE: 26/01/27 20:13:04 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 SHORT GRB At 20:02:32 UT on 27 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260127B (trigger 791236957.568148 / 260127835). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 190.4, Dec = 56.9 (J2000 degrees, equivalent to J2000 12h 41m, 56d 53'), with a statistical uncertainty of 5.2 degrees. The angle from the Fermi LAT boresight is 109.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260127835/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260127835/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260127835/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43533. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41632] GRB 260127A: Prompt enhanced Swift-XRT position
by GCN Circulars 27 Jan '26

27 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43532 SUBJECT: GRB 260127A: Prompt enhanced Swift-XRT position DATE: 26/01/27 19:08:40 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-XRT team: Using 1.6 ks of promptly downlinked XRT event data for GRB 260127A, we find an enhanced XRT position of the afterglow: RA, Dec: 231.87962, 6.76262 which is equivalent to: RA (J2000) = 15h 27m 31.11s Dec (J2000) = 00h 27m 03.03s with an uncertainty of 1.9 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/1444088. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43532. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41631] Swift GRB 260127A: Global MASTER-Net observations report
by GCN Circulars 27 Jan '26

27 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43531 SUBJECT: Swift GRB 260127A: Global MASTER-Net observations report DATE: 26/01/27 19:08:27 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 Swift GRB 260127A ( N. J. Klingler et al., GCN 43529) errorbox 3854 sec after notice time and 3972 sec after trigger time at 2026-01-27 18:56:47 UT, with upper limit up to 17.1 mag. The observations began at zenith distance = 77 deg. The sun altitude is -52.1 deg. The galactic latitude b = 47 deg., longitude l = 12 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3117002 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 3988 | MASTER-Tunka | C | 30 | 17.1 | 4030 | MASTER-Tunka | C | 30 | 17.1 | 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/43531. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41630] GRB 260127A: LCO optical afterglow discovery
by GCN Circulars 27 Jan '26

27 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43530 SUBJECT: GRB 260127A: LCO optical afterglow discovery DATE: 26/01/27 19:06:16 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> A. Saccardi (CEA/Irfu), D. B. Malesani (DAWN/NBI and Radboud) report on behalf of the SVOM mission team: We observed the field of GRB 260127A (Fermi GBM team, GCN 43528; Klingler et al., GCN 43529) with the LCO 1-m telescope at Siding Spring Observatory equipped with the Sinistro instrument. Our observation started on 2026-01-27 at 18:12:42 (about 22 min after the trigger) and we obtained 3x200 s exposures in the SDSS r filter. An uncatalogued optical transient is detected within the XRT error box at the following coordinates (J2000): RA = 15:27:31.14 Dec = +06:45:45.49 with an uncertainty of 0.3". No object is visible at these coordinates in the much deeper archival images from the Legacy Survey, indicating that this object is most likely the optical afterglow of GRB 260127A. We measure the following magnitude, calibrated against the Pan-STARRS catalog, and not corrected for Galactic extinction: r = 20.45 +/- 0.20 AB (mid-time of 27.3 min after the trigger). Further observations are planned. This project is funded by the SVOM collaboration. View this GCN Circular online at https://gcn.nasa.gov/circulars/43530. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41629] GRB 260127A: Swift detection of a burst
by GCN Circulars 27 Jan '26

27 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43529 SUBJECT: GRB 260127A: Swift detection of a burst DATE: 26/01/27 18:17:19 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> N. J. Klingler (GSFC/UMBC/CRESSTII), R. Gupta (NASA GSFC), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), K. L. Page (U Leicester), T. M. Parsotan (GSFC) and B. Sbarufatti (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team: At 17:50:34 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 260127A (trigger=1444088). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 231.857, +6.758 which is RA(J2000) = 15h 27m 26s Dec(J2000) = +06d 45' 30" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed no structure initially, typical of an image trigger, with a more classic pulse structure starting at ~T0+20 sec. The emission has a duration of about 50 sec. The peak count rate was ~1460 counts/sec (15-350 keV), at ~33 sec after the trigger. The XRT began observing the field at 17:54:00.1 UT, 205.3 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 231.87885, 6.76345 which is equivalent to: RA(J2000) = 15h 27m 30.92s Dec(J2000) = +06d 45' 48.4" with an uncertainty of 3.5 arcseconds (radius, 90% containment). This location is 80 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (4.07 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.2 (+2.30/-2.03) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 4.58e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 213 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers none of the XRT error circle. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.049. Burst Advocate for this burst is N. J. Klingler (noelklin AT umbc.edu) Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) View this GCN Circular online at https://gcn.nasa.gov/circulars/43529. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41628] GRB 260127A: Fermi GBM Final Real-time Localization
by GCN Circulars 27 Jan '26

27 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43528 SUBJECT: GRB 260127A: Fermi GBM Final Real-time Localization DATE: 26/01/27 18:01:38 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 17:51:07 UT on 27 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260127A (trigger 791229072.735026 / 260127744). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 226.9, Dec = -2.2 (J2000 degrees, equivalent to J2000 15h 07m, -2d 12'), with a statistical uncertainty of 5.1 degrees. The angle from the Fermi LAT boresight is 79.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260127744/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260127744/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260127744/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43528. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41627] GRB 260125A: Swift-XRT observations
by GCN Circulars 27 Jan '26

27 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43527 SUBJECT: GRB 260125A: Swift-XRT observations DATE: 26/01/27 15:36:17 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), S. Dichiara (PSU), J.A. Kennea (PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), S. Campana (INAF-OAB) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/GBM-detected burst GRB 260125A (Fermi GBM Team, GCN 43510), collecting 3.1 ks of Photon Counting (PC) mode data between T0+64.9 ks and T0+86.3 ks. No X-ray sources have been detected consistent with the GOTO counterpart position (Gompertz et al., GCN 43514). The 3-sigma upper limit in the field is 0.003 ct s^-1, corresponding to a 0.3-10 keV observed flux of 1.0e-13 erg cm^-2 s^-1 (assuming a typical GRB spectrum). Five uncatalogued sources were detected too far from the GOTO position, and not showing significant signs of fading to be likely afterglow candidates. The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/ToO_GRBs/00021899. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43527. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41626] EP260126a: EP-FXT follow-up observation
by GCN Circulars 27 Jan '26

27 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43526 SUBJECT: EP260126a: EP-FXT follow-up observation DATE: 26/01/27 13:40:40 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> S.Y. Fu (HUST), Z.M. Wang (BNU), J.H. Wu (GZHU), H.Y. Liu, H.W. Pan (NAOC, CAS) on behalf of the Einstein Probe (EP) team: EP-FXT performed a follow-up observation of EP260126a (detected by EP-WXT, GCN 43520) about 19.1 hours after the WXT detection, with an exposure time of 5.8 ks. The FXT telemetry data show that an uncatalogued source was detected within the WXT error circle at R.A. = 103.7551, DEC = 37.7053 (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic). The FXT X-ray spectrum of this uncatalogued source can be fitted with an absorbed powerlaw with a hydrogen column density fixed at the Galactic value of 1.21 x 10^21 cm^-2 and a photon index of 1.76 (+/- 0.20). The derived unabsorbed 0.5-10 keV flux is approximately 5.65 (+1.0/-0.85) x 10^-13 erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. Multi-band follow-up observations are encouraged. 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/43526. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41625] EP260126a: Optical upper limit with Kinder observations
by GCN Circulars 27 Jan '26

27 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43525 SUBJECT: EP260126a: Optical upper limit with Kinder observations DATE: 26/01/27 12:48:50 GMT FROM: Amar Aryan at National Central University, Institute of Astronomy (NCUIA) <amararyan941(a)gmail.com> M.-H. Lee, A. Aryan, T.-W. Chen, C.-S. Lin (all NCU), A. K. H. Kong (NTHU), J. H. Gillanders, S. J. Smartt (both Oxford), Y. J. Yang (NYUAD), Y.-H. Lee, A. Sankar.K, Y.-C. Pan, C.-C. Ngeow, C.-H. Lai, W.-J. Hou, H.-Y. Hsiao, H.-C. Lin, J.-K. Guo (all NCU), S. Yang, Z. N. Wang, L. L. Fan, G. H. Sun (all HNAS), H.-W. Lin (UMich), H. F. Stevance, S. Srivastav, L. Rhodes (all Oxford), M. Nicholl, M. Fulton, T. Moore, K. W. Smith, C. Angus, A. Aamer (all QUB), A. Schultz and M. Huber (both IfA, Hawaii) report: We observed the field of the fast X-ray transient EP260126a (Fu et al., GCN 43520) using the 40cm SLT at Lulin Observatory in Taiwan as part of the Kinder collaboration (Chen & Yang et al., 2025, ApJ, 983, 86, doi:10.3847/1538-4357/adb428). The first SLT epoch of observations in r-band started at 13:53 UTC on the 26 January 2026 (MJD 61066.578), 9.46 hr after the EP-WXT trigger. We utilized the astroalign (Beroiz et al., 2020, A&C, 32, 100384) and astropy (Astropy Collaboration et al., 2022, ApJ, 935, 167) packages to align and stack the individual frames. Moreover, we used AutoPhOT (Brennan & Fraser, 2022, A&A, 667, A62) to perform PSF photometry. We do not detect any new or uncataloged sources within the 20" EP-FXT localization circle. The details of the observations and the measured 3-sigma upper limits (in the AB system) are as follows: Telescope | Filter | MJD (start)| t-t0 (hr) | Exposure (s) | Magnitude | avg. Seeing | med. Airmass SLT | r | 61066.578 | 9.46 | 300 * 6 | >21.0 | 2".8 | 1.04 SLT | i | 61066.606 | 10.14 | 300 * 3 | >20.3 | 2".5 | 1.03 The non-detections in our observations are consistent with those reported by Zhu et al. (GCN 43521), Globus et al. (GCN 43522), Eyles-Ferris et al. (GCNs 43523 and 43524). The presented upper limits are calibrated using the field stars from the Pan-STARRS catalog and are not corrected for the expected Galactic foreground extinction of A_r = 0.24 and A_i = 0.18 mag in the direction of the transient (Schlafly & Finkbeiner 2011). The methodology, details on the Lulin observatory telescopes, and a compilation of our optical follow-up campaign for FXTs discovered within the first year of operation of the Einstein-Probe mission are presented in Aryan et al., 2025, ApJS, 281, 20, doi:10.3847/1538-4365/adfc69. View this GCN Circular online at https://gcn.nasa.gov/circulars/43525. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41624] EP260126a: Liverpool Telescope optical upper limits
by GCN Circulars 27 Jan '26

27 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43524 SUBJECT: EP260126a: Liverpool Telescope optical upper limits DATE: 26/01/27 09:58:21 GMT FROM: Rob Eyles-Ferris at U of Leicester <raje1(a)leicester.ac.uk> R. A. J. Eyles-Ferris and N. Habeeb (Leicester) report on behalf of a larger collaboration: We observed the field of EP260126a (Fu et al., GCN 43520) with the 2m Liverpool Telescope on La Palma using the IO:O instrument. We obtained 6x150s exposures in each of the SDSS i’ and SDSS g’ filters starting at 2026-01-26 23:48:56 UT, approximately 19.4 hours after the X-ray detection. We performed image subtraction on the stacked images using reference images from Pan-STARRS and also compared the stacked and reference images manually. Within the EP/FXT localisation, and across the field, we detect no new sources in either the subtractions or stacked images consistent with the results of Zhu et al. (GCN 43521), Globus et al. (GCN 43522) and Eyles-Ferris et al. (GCN 43523). We derive 3-sigma upper limits of i’ > 23.3 and g’ > 23.0 with photometry calibrated to Pan-STARRS and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43524. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41623] EP260126a: Further NOT optical upper limits
by GCN Circulars 27 Jan '26

27 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43523 SUBJECT: EP260126a: Further NOT optical upper limits DATE: 26/01/27 09:56:26 GMT FROM: Rob Eyles-Ferris at U of Leicester <raje1(a)leicester.ac.uk> R. A. J. Eyles-Ferris (Leicester), D. B. Malesani (DAWN/NBI and Radboud), J. A. Quirola-Vasquez (Radboud), J. N. D. van Dalen (Radboud), G. Corcoran (UCD), P. G. Jonker (Radboud), A. Martin-Carrillo (UCD) and A. J. Levan (Radboud) report on behalf of a larger collaboration: We observed the field of the fast X-ray transient EP260126a (Fu et al., GCN 43520) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations were obtained in the SDSS r and z bands, consisting of 3x300 s and 5x200 s exposures, respectively, starting on 2026-01-26 at 23:08:13 UTC (~18.7 hr after the WXT trigger). No new source is detected within or at the border of the EP/FXT uncertainty region (Fu et al., GCN 43520) compared to Legacy DR10. From the stacked images, we obtain the following 3-sigma upper limits:  r > 24.3 z > 23.2 These upper limits are in AB magnitudes, calibrated using nearby stars from the Pan-STARRS catalog, and are not corrected for Galactic extinction. Our non-detection is consistent with the results of Zhu et al. (GCN 43521) and Globus et al. (GCN 43522). View this GCN Circular online at https://gcn.nasa.gov/circulars/43523. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41622] EP260126a: COLIBRÍ optical upper limits
by GCN Circulars 27 Jan '26

27 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43522 SUBJECT: EP260126a: COLIBRÍ optical upper limits DATE: 26/01/27 04:44:01 GMT FROM: globus(a)astro.unam.mx Noémie Globus (UNAM), Jean-Luc Atteia (IRAP), Alan M. Watson (UNAM), Rosa L. Becerra (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), 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), Benjamin Schneider (LAM), and Antonio de Ugarte Postigo (LAM) report: We imaged the field of EP 260126a (Fu et al., GCN Circ. 43520) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-01-27 02:21 to 04:06 UTC (from 21.9 to 23.7 hours after the trigger) and obtained 79 minutes of 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 was not corrected for Galactic extinction. In the stacked image, comparing to LS (Dey et al. 2019), we do not detect any new source at the FXT uncertainty region (Fu et al., GCN Circ. 43520) down to the following preliminary 5-sigma limits: r > 24.0, z > 23.1. 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/43522. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41621] EP260126a: NOT optical observations
by GCN Circulars 27 Jan '26

27 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43521 SUBJECT: EP260126a: NOT optical observations DATE: 26/01/27 04:35:07 GMT FROM: Dong Xu at NAOC/CAS <dxu(a)nao.cas.cn> Z.P. Zhu, J. An, X. Liu, S.Q. Jiang, L.B. He, D. Xu (NAOC), S.Y. Fu (HUST), J.P.U. Fynbo (DAWN/NBI), S. Bijavara (NOT) report on behalf of a large collaboration: We observed the field of EP260126a (Fu et al., GCN 43520) using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations started at 22:13:05 UT on 2026-01-26, i.e., 17.8 hr after the EP trigger, and we obtained 5 x 180 s frames in the Sloan r-band and 5 x 200 s frames in the Sloan z- band. No new optical source is detected within the EP/FXT error circle (Fu et al., GCN 43520), down to 5-sigma upper limits of r ~ 23.6 and z ~ 22.5, calibrated with nearby Pan-STARRS stars and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43521. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41620] EP260126a: Einstein Probe detection of a fast X-ray transient
by GCN Circulars 27 Jan '26

27 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43520 SUBJECT: EP260126a: Einstein Probe detection of a fast X-ray transient DATE: 26/01/27 02:36:26 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> S.Y. Fu (HUST), Z.M. Wang (BNU), J.H. Wu (GZHU), H.Y. Liu, H.W. Pan (NAOC, CAS) on behalf of the Einstein Probe (EP) team: We report on the detection of a fast X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP260126a. The event started at 2026-01-26T04:25:01 (UTC) and lasted for about 1400 seconds. The WXT position of the source is R.A. = 103.737 deg, DEC = 37.699 deg (J2000) with an uncertainty of 2.1 arcmin in radius (90% C.L. statistical and systematic). The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a photon index of 1.16(-/+0.17) and with a fixed galactic hydrogen column density of 1.21 x 10^21 cm^-2. The derived average unabsorbed 0.5-4 keV flux is 2.77 (-0.26/+0.29) x 10^-10 erg/s/cm^2. The peak flux in the 0.5-4 keV band reaches 1.49(-0.14/+0.16) x 10^-9 erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed at 2026-01-26T23:08:05 (UTC), about 19 hours after the trigger. Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 103.7537 deg, DEC = 37.7067 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). Further information will be updated when the telemetry data is received. 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/43520. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41619] Fermi-LAT Gamma-ray Observations of IceCube-260125A
by GCN Circulars 26 Jan '26

26 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43519 SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-260125A DATE: 26/01/26 21:49:24 GMT FROM: Leo Pfeiffer at University of Würzburg <pfeiffer.leo(a)gmail.com> L. Pfeiffer (Univ. of Wuerzburg), S. Buson (DESY, Univ. of Wuerzburg) and S. Garrappa (Weizmann Institute of Science) on behalf of the Fermi-LAT collaboration: We report an analysis of observations of the vicinity of the high-energy IC260125A neutrino event (GCN 43512) with all-sky survey data from the Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope. The IceCube event was detected on 2026-01-25 at 10:09:39.88 UTC (T0) with J2000 position RA = 243.72 (+0.52, -0.56) deg, Decl. = 6.69 (+0.62, -0.61) deg 90% PSF containment (J2000). No cataloged gamma-ray sources are found within the 90% IC260125A localization error (4FGL-DR4; The Fourth Fermi-LAT catalog Data Release 4, The Fermi-LAT collaboration 2023, arXiv:2307.12546). We searched for the existence of intermediate (days to years) timescale emission from a new gamma-ray transient source. Preliminary analysis indicates no significant (>5sigma) new excess emission (> 100 MeV) within the IC260125A 90% confidence localization. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC260125A best-fit position, the >100 MeV flux upper limit (95% confidence) is < 1.4e-10 ph cm^-2 s^-1 for ~17-years (2008-08-04 / T0), <5.3e-09 (<8.8e-08) ph cm^-2 s^-1 for a 1-month (1-day) integration time before T0. Since Fermi normally operates in an all-sky scanning mode, regular monitoring of this source will continue. For this analysis, the Fermi-LAT contact person is L. Pfeiffer (leonard.pfeiffer at uni-wuerzburg.de). The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. View this GCN Circular online at https://gcn.nasa.gov/circulars/43519. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41618] GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
by GCN Circulars 26 Jan '26

26 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43518 SUBJECT: GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf DATE: 26/01/26 14:19:11 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani(a)nbi.ku.dk> D. B. Malesani (DAWN/NBI and Radboud), B. P. Gompertz (Birmingham), G. Corcoran (UCD), L. Izzo (INAF/OAC and DARK/NBI), A. Martin-Carrillo (UCD), S. Bijavara Seshashayana (NOT), report on behalf of a larger collaboration: We observed the optical candidate GOTO26acv / AT 2026bjf (Gompertz et al., GCN 43514) of the Fermi GRB 260125A (Fermi GBM team, GCN 43510) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations were carried out using the SDSS griz filters, and started on 2026 Jan 25.995 UT (16.27 hr after the Fermi/GBM trigger). Visual inspection reveals no obvious point source at the coordinates of GOTO26acv / AT 2026bjf, on top of the galaxy PGC 139241 (LEDA 139241), in any of the observed bands, though we note that the bright and complex morphology of the galaxy makes a clear identification tough. Image subtraction against the Legacy survey archival images yields an upper limit r > 22.75 (AB) at a mean time of 16.47 hr after trigger (5x150 s exposure time). This value is calibrated against the Pan-STARRS catalog and is not corrected for Galactic extinction. Our limit is notionally deeper than the extrapolation of the power-law decay reported by Gompertz et al. (GCN 43514), even after accounting for a GOTO/ALFOSC color term and the quoted decay index uncertainty. View this GCN Circular online at https://gcn.nasa.gov/circulars/43518. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41617] Konus-Wind detection of GRB 260120B
by GCN Circulars 26 Jan '26

26 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43517 SUBJECT: Konus-Wind detection of GRB 260120B DATE: 26/01/26 13:06:35 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru> A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long-duration GRB 260120B (Fermi GBM detection: Fermi GBM team, GCN 43477; Godwin & Meegan, GCN 43489; Swift-BAT detection: Ferro et al., GCN 43479; Palmer et al., GCN 43493; AstroSat CZTI detection: Goyal et al., GCN 43504) triggered Konus-Wind at T0=64826.649 s UT (18:00:26.649). The burst light curve shows a single pulse, which starts at ~T0-3.2 s and has a total duration of ~5.9 s. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260120_T64826/ As observed by Konus-Wind, the burst had a fluence of 3.41(-0.52,+0.58)x10^-6 erg/cm2, and a 64-ms peak flux, measured from T0-0.064 s, of 1.97(-0.58,+0.60)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). Since a major part of the burst emission was detected before the trigger, the spectral analysis was performed using the KW 3-channel light curve data. Modelling the KW 3-channel time-integrated spectrum (measured from T0-3.173 s to T0+2.720 s) by a power law with exponential cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), yields alpha = -0.56(-0.23,+0.30) and Ep = 246(-53,+67) keV. 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/43517. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41616] GRB 251222A: SVOM/ECLAIRs refined analysis
by GCN Circulars 26 Jan '26

26 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43516 SUBJECT: GRB 251222A: SVOM/ECLAIRs refined analysis DATE: 26/01/26 11:12:41 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Hui Yang, Sebastien Guillot, Olivier Godet, Marius Brunet, Guangxuan Lan (IRAP) Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of GRB 251222A (SVOM burst-id sb25122206, GCN 43188). The burst that triggered ECLAIRs consists of multiple peaks, and is detected for more than 200 s in the 4-120 keV energy band. The time-averaged spectrum before the slew from T0-14 s to T0+37 s (T0 = 2025-12-22T17:05:46) in the energy range 5-120 keV is best fitted by a cutoff power-law model with a photon index of 1.3+/-0.1, an Ecut of 54(+29/-15) keV, giving a corresponding 4-120 keV flux of (4.9+/-0.3)e-8 erg/cm^2/s. The spectrum from T0+162 s to T0+192 s after the slew in the energy range 5-120 keV is well fitted by a power-law model with a photon index of 2.4 +/-0.2 giving a corresponding 4-120 keV flux of (9+/-1)e-9 erg/cm^2/s. All the quoted errors are at the 68% confidence level. 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. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs point of contact for this burst is: Hui Yang (IRAP) (hyang(a)irap.omp.eu) View this GCN Circular online at https://gcn.nasa.gov/circulars/43516. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41615] GRB 260125A: Swift ToO observations
by GCN Circulars 26 Jan '26

26 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43515 SUBJECT: GRB 260125A: Swift ToO observations DATE: 26/01/26 02:44:30 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 Fermi/GBM-detected event GRB 260125A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021899 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 Fermi/GBM 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/43515. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41614] GRB 260125A: GOTO candidate optical counterpart
by GCN Circulars 25 Jan '26

25 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43514 SUBJECT: GRB 260125A: GOTO candidate optical counterpart DATE: 26/01/25 20:20:30 GMT FROM: Ben Gompertz at U of Birmingham <b.gompertz(a)bham.ac.uk> B. P. Gompertz, S. Moran, D. O’Neill, R. Starling, K. Ackley, M. Dyer, J. Lyman, K. Ulaczyk, D. Steeghs, D. Galloway, V. Dhillon, P. O'Brien, G. Ramsay, K. Noysena, R. Kotak, R. Breton, J. Casares, L. Nuttall, B. Godson, T. Killestein, A. Kumar, M. Pursiainen report 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 GRB 260125A (Fermi GBM Team, GCN 43510). Observations from GOTO-South (Siding Spring) covering the localisation area began at 2026-01-25 12:06:29 UT (+4.49h post trigger) and continued through to 2026-01-25 15:46:04 UT (+8.54h post trigger). 292 images were taken, across 16 unique pointings, covering 510.2 within the 90% localisation contour. ~78.0% of the total 2D localisation probability was covered, with an average 5-sigma depth of 20.8 mag. Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations. Source candidates were initially filtered using a classifier (Killestein et al. 2021) and cross-matched against a variety of contextual and minor planet catalogs. Human vetting was carried out in real time on any candidates that passed the above checks. Within the 90% probability region, we identify a new transient, GOTO26acv (AT 2026bjf), lying on the 20th percentile contour of the GBM localisation map at coordinates: RA = 10:06:16.71, Dec = -06:34:33.55 (J2000), equivalent to RA = 151.56962, Dec = -6.57599 degrees. GOTO26acv / AT 2026bjf was discovered with an AB magnitude of L = 20.17 ± 0.16 in an epoch taken at 12:29:25 UT, i.e. 4.87h post-trigger. Across three epochs of detection, it was observed to fade by 0.42 ± 0.25 magnitudes in 2.35 hours, equivalent to a power-law decay rate of t^-0.92 ± 0.38. The final detection magnitude was L = 20.59 ± 0.19 at 14:50:26 UT. The source is spatially coincident with the galaxy PGC 139241 at a luminosity distance of 53 Mpc. It is offset from the nucleus by ~9”. The source was not present in the most recent survey image of the field, taken at 13:37:58 UT on 2026-01-24 (0.75 days prior to the GRB trigger), to a 3-sigma limiting magnitude of L > 20.95. We also find no evidence of GOTO26acv / AT 2026bjf prior to the GRB trigger time in the ZTF observations provided by the Lasair broker (Smith et al. 2019), or the ATLAS forced photometry server (Shingles et al. 2021). Further follow-up observations to establish the nature of GOTO26acv / AT2026bjf and its potential association with GRB 260125A are encouraged. Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and not corrected for Galactic extinction. 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/43514. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41613] Fermi GRB 260125B: Global MASTER-Net observations report
by GCN Circulars 25 Jan '26

25 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43513 SUBJECT: Fermi GRB 260125B: Global MASTER-Net observations report DATE: 26/01/25 11:45:33 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) started inspect of the Fermi GRB 260125B ( Fermi GBM team, GCN 43511) errorbox 3759 sec after notice time and 3791 sec after trigger time at 2026-01-25 11:28:56 UT, with upper limit up to 18.4 mag. Observations started at twilight. The observations began at zenith distance = 43 deg. The sun altitude is -16.2 deg. The galactic latitude b = -13 deg., longitude l = 185 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3114740 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 3821 | 2026-01-25 11:28:56 | MASTER-Tunka | (05h 18m 03.87s , +20d 44m 22.3s) | C | 60 | 18.4 | 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/43513. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41612] Fermi GRB 260125B: Global MASTER-Net observations report
by GCN Circulars 25 Jan '26

25 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43513 SUBJECT: Fermi GRB 260125B: Global MASTER-Net observations report DATE: 26/01/25 11:45:33 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) started inspect of the Fermi GRB 260125B ( Fermi GBM team, GCN 43511) errorbox 3759 sec after notice time and 3791 sec after trigger time at 2026-01-25 11:28:56 UT, with upper limit up to 18.4 mag. Observations started at twilight. The observations began at zenith distance = 43 deg. The sun altitude is -16.2 deg. The galactic latitude b = -13 deg., longitude l = 185 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3114740 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 3821 | 2026-01-25 11:28:56 | MASTER-Tunka | (05h 18m 03.87s , +20d 44m 22.3s) | C | 60 | 18.4 | 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/43513. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41611] IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
by GCN Circulars 25 Jan '26

25 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43512 SUBJECT: IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 26/01/25 11:33:55 GMT FROM: A. Zegarelli at Ruhr University Bochum <azegarelli(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 26-01-25 at 10:09:39.88 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_BRONZE alert stream. The average astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 1.9783 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection. After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/141985_63695019.amon) more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 26-01-25 Time: 10:09:39.88 UT RA: 243.72 (+0.52/-0.56 deg 90% PSF containment) J2000 Dec: 6.69 (+0.62/-0.61 deg 90% PSF containment) J2000 As announced in GCN Circular 43419, IceCube alert notices for high-energy track alerts are now also streamed via Kafka. IceCube Gold/Bronze track alerts are available on the Kafka topic 'gcn.notices.icecube.gold_bronze_track_alerts'. The probability distribution of the true neutrino direction, allowing the extraction of precise 90% containment regions around the best-fit direction, is now available for revised reconstruction of high-energy track alerts. The corresponding sky map is distributed as a FITS file and follows the explicit naming convention IceCube-YYMMDDX (e.g. IceCube-260125A, for this alert), where YYMMDD indicates the date of the event and X is a letter distinguishing multiple alerts on the same day. The download link (e.g., for this alert https://roc-2.icecube.wisc.edu/public/alerts/IceCube-260125A_skymap_probden…) is provided through the GCN schema distributed via Kafka. Additional information will be soon available at https://gcn.nasa.gov/missions/icecube. In the near future, classical GCN stream will be deactivated. No known gamma-ray sources listed in the Fermi 4FGL-DR4 or 3FHL catalogs are located within the 90% uncertainty region of this event. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu View this GCN Circular online at https://gcn.nasa.gov/circulars/43512. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41610] GRB 260125B: Fermi GBM Final Real-time Localization
by GCN Circulars 25 Jan '26

25 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43511 SUBJECT: GRB 260125B: Fermi GBM Final Real-time Localization DATE: 26/01/25 10:36:26 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 10:25:45 UT on 25 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260125B (trigger 791029550.226442 / 260125435). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 77.1, Dec = 17.6 (J2000 degrees, equivalent to J2000 05h 08m, 17d 36'), with a statistical uncertainty of 11.6 degrees. The angle from the Fermi LAT boresight is 28.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260125435/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260125435/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260125435/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43511. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41609] GRB 260125A: Fermi GBM Final Real-time Localization
by GCN Circulars 25 Jan '26

25 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43510 SUBJECT: GRB 260125A: Fermi GBM Final Real-time Localization DATE: 26/01/25 07:47:31 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 07:36:58 UT on 25 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260125A (trigger 791019423.079276 / 260125317). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 148.7, Dec = -2.9 (J2000 degrees, equivalent to J2000 09h 54m, -2d 53'), with a statistical uncertainty of 8.9 degrees. The angle from the Fermi LAT boresight is 67.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260125317/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260125317/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260125317/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43510. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41608] GRB 260114A: SVOM/VT optical upper limits
by GCN Circulars 25 Jan '26

25 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43509 SUBJECT: GRB 260114A: SVOM/VT optical upper limits DATE: 26/01/25 04:16:37 GMT FROM: Yinuo Ma <mayn(a)bao.ac.cn> Y. N. Ma (NAOC), R. Z. Li (YNAO), L. P. Xin, H. L. Li, Z. H. Yao, Y. L. Qiu, C. Wu, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei, D. H. Zhao (NAOC), J. Palmerio (CEA), B. T. Wang (YNAO), Y. H. Cheng (YNU) report on behalf of the SVOM/VT team. SVOM/VT performed a Target of Opportunity observation of GRB 260114A detected by Swift/BAT, Fermi/GBM, SVOM/GRM, GECAM-B, Konus-Wind and Insight-HXMT/HE (Fermi GBM Team, GCN 43395; Eyles-Ferris et al., GCN 43396; Bissaldi, GCN 43400; Ren et al., GCN 43402; Wang et al., GCN 43404; Beardmore et al., GCN 43412; Ridnaia et al., GCN 43413; Ren et al., GCN 43503). SVOM/VT began observing the field at 2026-01-14 14:47:02 UTC, 3.11 hours after T0, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. We performed the second observation as a template on January 19th. After performing image subtraction of our stacked images against the second observation, no uncataloged candidate was detected within the error box provided by Swift/XRT position (Beardmore et al., GCN 43412) or the optical counterpart previously reported by GMG (Li et al., GCN Circ. 43398) and the Mondy observatory (Volnova et al., GCN Circ. 43401). The three sigma limits are: mid-time | exposure time | band | upper limit (AB) ----------|-----------------|-------|----------------- 4.241 h | 69*70 sec | VT_B | > 23.8 mag 4.251 h | 67*70 sec | VT_R | > 23.5 mag Our results are consistent with MASTER (Lipunov et al., GCN Circ. 43403), NOT (Corcoran et al., GCN Circ. 43406), TNG (Brivio et al., GCN Circ. 43407), COLIBRÍ (Angulo et al., GCN 43408), MITSuME (Takahashi et al., GCN 43409), VLT (Yang et al., GCN 43414; Schneider et al ., GCN 43423) and Swift/UVOT (Siegel & Eyles-Ferris, GCN 43473). 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/43509. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41607] GRB 260120A: AstroSat CZTI detection
by GCN Circulars 24 Jan '26

24 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43508 SUBJECT: GRB 260120A: AstroSat CZTI detection DATE: 26/01/24 11:33:06 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> Harsha K. H. (IUCAA), M. Tembhurnikar (IUCAA), S. Salunke (IUCAA), A. Arya (IITB), A. Goyal (IITB), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 260120A which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 43467), and GECAM-B (Guo et al., GCN Circ. 43505). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2026-01-20 04:01:55.50 UTC. The measured peak count rate associated with the burst is 264 (+132, -24) counts/s above the background in the combined data of three quadrants (out of four), with a total of 345 (+83, -77) counts. The local mean background count rate was 189 (+3, -7) counts/s. Using cumulative rates, we measure a T90 of 3.1 (+1.1, -0.8) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2026-01-20 04:01:54.79 UTC. The measured peak count rate associated with the burst is 246 (+62, -64) counts/s above the background in the combined data of all quadrants, with a total of 625 (+185, -199) counts. The local mean background count rate was 1120 (+5, -6) counts/s. We measure a T90 of 4.2 (+1.3, -1.5) s from the cumulative Veto light curve. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/43508. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41606] GRB 260122B: Swift-BAT refined analysis
by GCN Circulars 24 Jan '26

24 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43507 SUBJECT: GRB 260122B: Swift-BAT refined analysis DATE: 26/01/24 00:54:15 GMT FROM: Amy <yarleen(a)gmail.com> D. M. Palmer (LANL), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), A. Mei (INAF-OAB), M. J. Moss (GSFC), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 260122B (trigger #1443066) (Mei et al., GCN Circ. 43502). The ground analysis confirms that this event is indeed a GRB and not due to background fluctuations (Mei et al., GCN Circ. 43502). The BAT ground-calculated position is RA, Dec = 336.096, -59.176 deg which is RA(J2000) = 22h 24m 22.9s Dec(J2000) = -59d 10' 32.1" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 57%. The mask-weighted light curve shows a single-pulse structure that starts ~T-1 s, peaks at ~T+9 s, and ends at ~T+20 s. T90 (15-350 keV) is 16.59 +- 3.89 sec (estimated error including systematics). The time-averaged spectrum from T+0.23 to T+19.51 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.34 +- 0.17. The fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+8.46 sec in the 15-150 keV band is 1.6 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1443066 View this GCN Circular online at https://gcn.nasa.gov/circulars/43507. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41605] GRB 260120B: SVOM/GRM observation
by GCN Circulars 23 Jan '26

23 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43506 SUBJECT: GRB 260120B: SVOM/GRM observation DATE: 26/01/23 15:57:20 GMT FROM: renyz16607(a)163.com SVOM/GRM team: Yang-Zhao Ren, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Sebastien Guillot(IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered on-ground by GRB 260120B at 2026-01-20T18:00:26.200 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN #43477) and Swift/BAT (Ferro et al., GCN #43479). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a pulse with a T90 of 8.5 +5.0/-3.5 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb260120B.png In addition, the position of this burst, as determined by Swift/BAT (RA = 284.666, Dec = 61.912, GCN #43479), is located at about 89 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0 to T0+5 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.16 +0.16/-0.18 and the cutoff energy, parameterized as Epeak, is 307 +106/-62 keV. The event fluence (10-1000 keV) in this time interval is (3.78 +0.32/-0.33)E-06 erg/cm^2. The localization of GRB 260120B in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb260120B_amati.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 point of contact for this burst is: Yang-Zhao Ren (IHEP)(renyz(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/43506. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41604] GRB 260120A: GECAM-B observation
by GCN Circulars 23 Jan '26

23 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43505 SUBJECT: GRB 260120A: GECAM-B observation DATE: 26/01/23 15:39:23 GMT FROM: guohx(a)ihep.ac.cn Hao-Xuan Guo, Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered in-flight by GRB 260120A, at 2026-01-20T04:01:55.800 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #43467). According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of 2.3 +1.1/-0.7 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb260120A.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/43505. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41603] GRB 260120B: AstroSat CZTI detection
by GCN Circulars 23 Jan '26

23 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43504 SUBJECT: GRB 260120B: AstroSat CZTI detection DATE: 26/01/23 12:52:45 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> A. Goyal (IITB), A. Arya (IITB), M. Tembhurnikar (IUCAA), S. Salunke (IUCAA), Harsha K. H. (IUCAA), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 260120B which was also detected by Swift BAT (M. Ferro et. ala, GCN Circ. 43479), Fermi GBM (Fermi GBM Team, GCN Circ. 43477), Swift XRT (Goad et al., GCN Circ. 43484), and SVOM/C-GFT (Wu et al., GCN Circ. 43483). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2026-01-20 18:00:23.85 UTC. The measured peak count rate associated with the burst is 312 (+129, -23) counts/s above the background in the combined data of three quadrants (out of four), with a total of 622 (+153, -176) counts. The local mean background count rate was 174 (+4, -6) counts/s. Using cumulative rates, we measure a T90 of 5.0 (+1.5, -1.5) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2026-01-20 18:00:22.68 UTC. The measured peak count rate associated with the burst is 333 (+65, -44) counts/s above the background in the combined data of all quadrants, with a total of 1026 (+266, -251) counts. The local mean background count rate was 1065 (+7, -9) counts/s. We measure a T90 of 4.3 (+1.6, -1.8) s from the cumulative Veto light curve. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/43504. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41602] GRB 260114A: Insight-HXMT/HE detection
by GCN Circulars 23 Jan '26

23 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43503 SUBJECT: GRB 260114A: Insight-HXMT/HE detection DATE: 26/01/23 11:58:54 GMT FROM: renyz16607(a)163.com Yang-Zhao Ren, Chen-Wei Wang, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng (IHEP) report on behalf of the Insight-HXMT team: At 2026-01-14T11:40:26.300 (T0), Insight-HXMT/HE detected a short burst, GRB 260114A, which is also detected by Fermi/GBM (Fermi GBM team, GCN #43395), Swift/BAT (Eyles-Ferris et al., GCN #43396), GECAM-B (Ren et al., GCN #43402), SVOM/GRM (Wang et al., GCN #43404), and Konus-Wind (Ridnaia et al., GCN #43413). The Insight-HXMT/HE light curve mainly consists of multi-pulses with T90 of 0.28 +0.02/-0.02 s. The 1s peak rate, measured from T0-0.09 s, is 3104 cnts/sec. Insight-HXMT/HE detected a total of 3038 counts from this burst. The Insight-HXMT /HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb260114A.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://www.hxmt.org View this GCN Circular online at https://gcn.nasa.gov/circulars/43503. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41601] GRB 260122B: Swift detection of a burst
by GCN Circulars 22 Jan '26

22 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43502 SUBJECT: GRB 260122B: Swift detection of a burst DATE: 26/01/22 23:49:28 GMT FROM: Mike Siegel at PSU/Swift MOC <siegel(a)swift.psu.edu> A. Mei (INAF-OAB), R. Brivio (INAF-OAB), R. Gupta (NASA GSFC), A. Y. Lien (U Tampa) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 23:13:10 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 260122B (trigger=1443066). Swift did not slew immediately to the burst due to observing constraint. The BAT on-board calculated location is RA, Dec 336.079, -59.167 which is RA(J2000) = 22h 24m 19s Dec(J2000) = -59d 10' 02" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 15 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~0 sec after the trigger. We note that the burst occurred during the high background interval near the SAA. Therefore, at this moment we cannot completely rule out the possibility that the event is due to background fluctuation. However, given that the image significance is 9.35 sigma, we believe this is likely a real burst. Further ground data is required to determine the nature of the burst. Due to a Sun observing constraint, Swift cannot slew to the BAT position until 2026 February 16. There will thus be no XRT or UVOT data for this trigger. Burst Advocate for this burst is A. Mei (alessio.mei AT inaf.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) View this GCN Circular online at https://gcn.nasa.gov/circulars/43502. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41600] Swift GRB260122.97: Global MASTER-Net observations report
by GCN Circulars 22 Jan '26

22 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43501 SUBJECT: Swift GRB260122.97: Global MASTER-Net observations report DATE: 26/01/22 23:22:27 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-SAAO robotic telescope [1] located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB260122.97 (trigger No 1443066,22h 24m 18.96s , -59d 10m 01.2s, R=0.05) errorbox 84 sec after notice time and 187 sec after trigger time at 2026-01-22 23:16:17 UT, with upper limit up to 15.9 mag. The observations began at zenith distance = 87 deg. The sun altitude is -38.0 deg. The galactic latitude b = -50 deg., longitude l = 331 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3112208 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 207 | MASTER-SAAO | P\ | 40 | 15.9 | 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/43501. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41599] EP260119a: Assy AZT-20 optical observations
by GCN Circulars 22 Jan '26

22 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43500 SUBJECT: EP260119a: Assy AZT-20 optical observations DATE: 26/01/22 12:09:42 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), A. Pozanenko (IKI), M. Krugov (FAI), N. Pankov (IKI) report on behalf of IKI-GRB-FuN: We observed the field of the EP260119a (Jiang et al., GCN 43447; GCN 43465; Cheng et al., GCN 43449) at the redshift of z ~ 5.47 (Corcoran et al., GCN 43469) with the AZT-20 telescope of Assy-Turgen observatory starting on 2026-01-20 (UT) 14:53 and taking several 60-second exposures in i' filter. In the stacked frame we detect the optical counterpart (Fortin et al., GCN 43450; GCN 43455; Eyles-Ferris et al., GCN 43452; Moskvitin and Spiridonova, GCN 43463; Liu et al., GCN 43464; Ma et al., GCN 43466; Zheng et al., GCN 43468; Corcoran et al., GCN 43469; Bochenek and Perley, GCN 43472; Pankov et al., GCNs 43476, 43499; Jin et al., GCN 43496). Preliminary photometry and observational details are the following: Date UT start t-T0 Exp. Filter Obj. Err. UL Site/Telescope (mid,days) (n*s) (3sigma) 2026-01-20 14:53:00 1.63500 63*60 i' 22.7 0.2 23.2 Assy-Turgen/AZT-20 The photometry is based on several nearby SDSS stars (i-magnitudes) and is not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43500. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41598] EP260119a: Mondy and SAO RAS optical upper limits
by GCN Circulars 22 Jan '26

22 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43499 SUBJECT: EP260119a: Mondy and SAO RAS optical upper limits DATE: 26/01/22 10:50:53 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> N. Pankov (IKI), A. Moskvitin (SAO RAS), A. Volnova (IKI), O. Spiridonova (SAO RAS), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of the IKI-GRB-FuN collaboration: We observed the field of the EP260119a (Jiang et al., GCN 43447; GCN 43465; Cheng et al., GCN 43449) at the redshift of z ~ 5.47 (Corcoran et al., GCN 43469) using the AZT-33IK telescope of the Mondy observatory starting on 2026-01-20 (UT) 18:52:22 and 2026-01-21 (UT) 19:10:23, and the Zeiss-1000 of the SAO RAS starting on 2026-01-21 (UT) 03:05:44. In the stacked frame of each observational epoch we do not detect the optical source reported previously (Fortin et al., GCN 43450; GCN 43455; Eyles-Ferris et al., GCN 43452; Moskvitin and Spiridonova, GCN 43463; Liu et al., GCN 43464; Ma et al., GCN 43466; Zheng et al., GCN 43468; Corcoran et al., GCN 43469; Bochenek and Perley, GCN 43472; Pankov et al., GCN 43476; Jin et al., GCN 43496). Preliminary photometry and observation details are listed below: Date UT start t-T0 Exp. Filter Mag MagErr. UL Site/Telescope (mid,days) (n*s) (3sigma) 2026-01-20 18:52:22 1.80804 45x120 I n/d n/d 22.3 Mondy/AZT-33IK 2026-01-21 03:05:44 2.13449 8*300 Ic n/d n/d 21.9 SAO RAS/Zeiss-1000 2026-01-21 19:10:23 2.82417 52*120 I n/d n/d 21.7 Mondy/AZT-33IK Photometric data are based on nearby SDSS stars (I-magnitudes obtained using the 2005 Lupton transform) and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43499. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41597] GRB 260122A: Fermi GBM Final Real-time Localization
by GCN Circulars 22 Jan '26

22 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43498 SUBJECT: GRB 260122A: Fermi GBM Final Real-time Localization DATE: 26/01/22 09:44:17 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 09:33:43 UT on 22 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260122A (trigger 790767228.420398 / 260122398). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 307.8, Dec = -12.8 (J2000 degrees, equivalent to J2000 20h 31m, -12d 48'), with a statistical uncertainty of 6.5 degrees. The angle from the Fermi LAT boresight is 65.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260122398/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260122398/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260122398/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43498. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41596] IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
by GCN Circulars 22 Jan '26

22 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43497 SUBJECT: IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility DATE: 26/01/22 08:15:17 GMT FROM: Jannis Necker at DESY <jannis.necker(a)desy.de> Akshay Eranhalodi (DESY), Robert Stein (JSI), Jannis Necker (Leiden University), and Anna Franckowiak (Ruhr University Bochum) report, On behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations: As part of the ZTF neutrino follow up program (Stein et al. 2023), we observed the localization region of the neutrino event IceCube-260115A (Zegarelli et. al, GCN 43421) with the Palomar 48-inch telescope, equipped with the 47 square degree ZTF camera (Bellm et al. 2019, Graham et al. 2019). We started observations in the g- and r-band beginning at 2026-01-16 05:53 UTC, approximately 12.3 hours after event time. We covered 99.2% (8.2 sq deg) of the reported localization region. This estimate accounts for chip gaps. Each exposure was 300s with a typical depth of 21.0 mag. The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts (Masci et al. 2019). AMPEL (Nordin et al. 2019, Stein et al. 2021) was used to search the alerts database for candidates. We reject stellar sources (Tachibana and Miller 2018) and moving objects, and apply machine learning algorithms (Mahabal et al. 2019) . We are left with one transient candidate by our pipeline within the 90.0% localization of the skymap. +--------------------------------------------------------------------------------+ | ZTF Name | IAU Name | RA (deg) | DEC (deg) | Filter | Mag | MagErr | +--------------------------------------------------------------------------------+ | ZTF26aabnqai | AT2026azb | 145.5760425 | +13.0239392 | r | 21.08 | 0.15 | +--------------------------------------------------------------------------------+ ZTF26aabnqai was first detected on 2026-01-16 at an apparent magnitude of about 21 mag in r-band. The g-r color is around 0.5 mag. Forced photometry revealed previous detections up to a week earlier with a fading rate of about 0.5 mag per day. The host galaxy has a photometric redshift of 0.23 +/- 0.08 in Legacy Survey. During our latest observatiosn the transient was no longer detectable, consistent with continued fading. This makes the transients too faint for our spectroscopic programs. However, the color, fade time and inferred absolute magnitude are all broadly consistent with a Type Ia supernova. These are not expected to emit high-energy neutrinos and thus we consider ZTF26aabnqai unlikely to be related to IceCube-260115A. We further identify following quasars without contemporaneous flaring activity. The hosts of ZTF22aaejlfn (SDSS J094112.55+131224.9), ZTF25aadwsdp (SDSS J093659.79+124616.6), ZTF25aadxqgk (SDSS J094449.16+120545.5), and ZTF25aarudkx (SDSS J094755.84+125346.4) are listed in MILLIQUAS (Flesch et al., 2023). ZTF24abwkvpl was first detected on 2024-11-05. Its host, SDSS J093633.62+131948.5, is part of a selection of quasars by SDSS photometry (Richards et al., 2009). The hosts of ZTF25aaedxfb, and ZTF25aadxmes show red, AGN-like WISE colors with W1-W2>0.8 (Stern et al., 2012). ZTF25abttvfc was consistently detected over the last 100 days with varying brightness. ZTF18acqfhyp, ZTF25aadnych, and ZTF25aadoovh were sporadically detected before the neutrino arrival and are likely variable sources at the sensitivity limit. ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA; WIS, Israel; OKC, Sweden; JSI/UMd, USA; DESY, Germany; TANGO, Taiwan; UW Milwaukee, USA; LANL, USA; TCD, Ireland; IN2P3, France. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. Alert distribution service provided by DIRAC@UW (Patterson et al. 2019). Alert database searches are done by AMPEL (Nordin et al. 2019). Alert filtering is performed with the nuztf (Stein et al. 2021, https://github.com/desy-multimessenger/nuztf ). View this GCN Circular online at https://gcn.nasa.gov/circulars/43497. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41595] EP260119a: Xinglong optical upper limit
by GCN Circulars 22 Jan '26

22 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43496 SUBJECT: EP260119a: Xinglong optical upper limit DATE: 26/01/22 03:29:52 GMT FROM: Xinglong Observatory at National Astronomical Observatories (NAOC), Chinese Academy of Sciences (CAS) <xinglong(a)nao.cas.cn> Junjie-Jin (NAOC), Haiyang-Mu (NAOC), Sen-Liu (NAOC), Pengliang-Du (NAOC), Zhou-Fan (NAOC), Hong-Wu (NAOC) report: Following the detection of EP260119a by EP-WXT (GCN Circular 43447,GCN Circular 43452), we observed the field of EP260116a using the 2.16-m telescope at Xinglong Observatory, NAOC. We obtained 600s clear-band frames with a median time of 2026-01-19T18:38:00 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 43447), down to 5-sigma limiting magnitudes of z ~ 19.8(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 43452), the target was not observed. View this GCN Circular online at https://gcn.nasa.gov/circulars/43496. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41594] The EP-WXT trigger 01709251871 is likely a flaring star
by GCN Circulars 22 Jan '26

22 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43495 SUBJECT: The EP-WXT trigger 01709251871 is likely a flaring star DATE: 26/01/22 01:53:51 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> R.D. Liang (NAOC), Z. X. Li, G. L. Huang, C. Wang (IHEP) and Y. Liu (NAOC) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709251871 at the time of 2026-01-22T00:00:14, is likely a stellar flare associated with [M81] I-308. The estimated flux of the flare is around 1x10^-10 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 8.5x10^31 erg/s. 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/43495. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41593] The EP-WXT trigger 01709251871 is likely a flaring star
by GCN Circulars 22 Jan '26

22 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43495 SUBJECT: The EP-WXT trigger 01709251871 is likely a flaring star DATE: 26/01/22 01:53:51 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> R.D. Liang (NAOC), Z. X. Li, G. L. Huang, C. Wang (IHEP) and Y. Liu (NAOC) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709251871 at the time of 2026-01-22T00:00:14, is likely a stellar flare associated with [M81] I-308. The estimated flux of the flare is around 1x10^-10 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 8.5x10^31 erg/s. 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/43495. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41592] Fermi GRB 260120C: Global MASTER-Net observations report
by GCN Circulars 22 Jan '26

22 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43494 SUBJECT: Fermi GRB 260120C: Global MASTER-Net observations report DATE: 26/01/22 00:30:53 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 260120C ( Fermi GBM team, GCN 43482) errorbox 1 days 3994 sec after notice time and 1 days 4027 sec after trigger time at 2026-01-22 00:14:13 UT, with upper limit up to 16.8 mag. The observations began at zenith distance = 81 deg. The sun altitude is -47.2 deg. The galactic latitude b = 20 deg., longitude l = 26 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3110218 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 44777 | 2026-01-21 11:32:53 | MASTER- | (17h 17m 02.82s , +06d 50m 25.2s) | C | 60 | 18.4 | 44777 | 2026-01-21 11:32:53 | MASTER- | (17h 18m 05.82s , +06d 16m 01.2s) | C | 60 | 18.4 | 44847 | 2026-01-21 11:34:03 | MASTER- | (17h 25m 13.44s , +06d 50m 33.0s) | C | 60 | 18.3 | 44847 | 2026-01-21 11:34:03 | MASTER- | (17h 26m 16.06s , +06d 16m 06.1s) | C | 60 | 18.2 | 45387 | 2026-01-21 11:43:03 | MASTER- | (17h 18m 07.00s , +06d 16m 05.5s) | C | 60 | 18.6 | 45387 | 2026-01-21 11:43:03 | MASTER- | (17h 17m 03.38s , +06d 50m 02.6s) | C | 60 | 18.5 | 45457 | 2026-01-21 11:44:13 | MASTER- | (17h 26m 15.40s , +06d 16m 14.1s) | C | 60 | 18.5 | 45457 | 2026-01-21 11:44:13 | MASTER- | (17h 25m 12.21s , +06d 50m 13.9s) | C | 60 | 18.4 | 46057 | 2026-01-21 11:54:13 | MASTER- | (17h 17m 05.56s , +06d 51m 19.0s) | C | 60 | 18.6 | 46057 | 2026-01-21 11:54:13 | MASTER- | (17h 18m 09.53s , +06d 17m 03.8s) | C | 60 | 18.8 | 46127 | 2026-01-21 11:55:23 | MASTER- | (17h 25m 09.25s , +06d 49m 58.4s) | C | 60 | 18.5 | 46127 | 2026-01-21 11:55:23 | MASTER- | (17h 26m 12.91s , +06d 15m 41.0s) | C | 60 | 18.6 | 46661 | 2026-01-21 12:04:17 | MASTER- | (17h 18m 10.15s , +06d 16m 41.1s) | C | 60 | 19.0 | 46661 | 2026-01-21 12:04:17 | MASTER- | (17h 17m 05.20s , +06d 51m 05.2s) | C | 60 | 18.7 | 46730 | 2026-01-21 12:05:26 | MASTER- | (17h 25m 08.92s , +06d 49m 31.9s) | C | 60 | 18.5 | 46730 | 2026-01-21 12:05:26 | MASTER- | (17h 26m 13.45s , +06d 15m 06.0s) | C | 60 | 18.8 | 47327 | 2026-01-21 12:15:23 | MASTER- | (17h 17m 06.31s , +06d 49m 15.8s) | C | 60 | 18.7 | 47327 | 2026-01-21 12:15:23 | MASTER- | (17h 18m 11.40s , +06d 14m 44.7s) | C | 60 | 19.0 | 47398 | 2026-01-21 12:16:33 | MASTER- | (17h 25m 11.28s , +06d 50m 36.4s) | C | 60 | 18.6 | 47398 | 2026-01-21 12:16:34 | MASTER- | (17h 26m 16.13s , +06d 16m 02.5s) | C | 60 | 18.9 | 47994 | 2026-01-21 12:26:30 | MASTER- | (17h 17m 04.57s , +06d 49m 46.2s) | C | 60 | 18.7 | 47994 | 2026-01-21 12:26:30 | MASTER- | (17h 18m 10.96s , +06d 15m 15.9s) | C | 60 | 19.1 | 48064 | 2026-01-21 12:27:40 | MASTER- | (17h 25m 06.47s , +06d 50m 37.4s) | C | 60 | 18.7 | 48064 | 2026-01-21 12:27:40 | MASTER- | (17h 26m 12.55s , +06d 16m 04.5s) | C | 60 | 19.1 | 90457 | 2026-01-22 00:14:13 | MASTER-Kislovodsk | (16h 55m 40.00s , +10d 25m 13.1s) | C | 60 | 16.7 | 90573 | 2026-01-22 00:16:09 | MASTER-Kislovodsk | (17h 02m 50.35s , +12d 18m 51.1s) | C | 60 | 16.7 | 90811 | 2026-01-22 00:20:07 | MASTER-Kislovodsk | (16h 45m 12.41s , +06d 36m 17.1s) | 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/43494. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41591] GRB 260120B: Swift-BAT refined analysis
by GCN Circulars 21 Jan '26

21 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43493 SUBJECT: GRB 260120B: Swift-BAT refined analysis DATE: 26/01/21 23:08:12 GMT FROM: D. R. Sadaula at NASA GSFC <dev.r.sadaula(a)nasa.gov> D. M. Palmer (LANL), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-769 to T+303 sec from the recent telemetry downlink, we report further analysis of BAT GRB 260120B (trigger #1442454) (Ferro et al., GCN Circ. 43479). The BAT ground-calculated position is RA, Dec = 284.701, 61.905 deg which is RA(J2000) = 18h 58m 48.3s Dec(J2000) = +61d 54' 19.2" with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 9%. The BAT light curve showed a single-peaked structure with a duration of about 10 sec. T90 (15-350 keV) is 4.48 +- 0.94 sec (estimated error including systematics). The time-averaged spectrum from T-0.34 to T+4.59 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index -0.93 +- 1.35, and Epeak of 103.9 +- 38.6 keV (chi squared 48.41 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.2 +- 0.1 x 10^-06 erg/cm2 and the 1-sec peak flux measured from T+0.48 sec in the 15-150 keV band is 3.1 +- 0.8 ph/cm2/sec. A fit to a simple power law gives a photon index of 0.95 +- 0.21 (chi squared 57.22 for 57 d.o.f.). All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1442454 View this GCN Circular online at https://gcn.nasa.gov/circulars/43493. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41590] GRB 260120B: Swift-XRT refined Analysis
by GCN Circulars 21 Jan '26

21 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43492 SUBJECT: GRB 260120B: Swift-XRT refined Analysis DATE: 26/01/21 20:20:55 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> M. Ferro (INAF-OAB), R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), S. Lanava (PSU), S. Dichiara (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 5.6 ks of XRT data for GRB 260120B, from 130 s to 29.5 ks after the trigger. The data comprise 13 s in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The light curve can be modelled with a power-law decay with a decay index of alpha=0.84 (+/-0.06). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.97 (+0.29, -0.27). The best-fitting absorption column is 2.1 (+1.2, -1.0) x 10^21 cm^-2, in excess of the Galactic value of 7.4 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.7 x 10^-11 (5.1 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.1 (+1.2, -1.0) x 10^21 cm^-2 Galactic foreground: 7.4 x 10^20 cm^-2 Excess significance: 2.4 sigma Photon index: 1.97 (+0.29, -0.27) The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/01442454. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43492. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41589] EP260116a: COLIBRÍ further observations
by GCN Circulars 21 Jan '26

21 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43491 SUBJECT: EP260116a: COLIBRÍ further observations DATE: 26/01/21 19:38:30 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), 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), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM) report: We observed the field of EP260116a (Wang et al., GCN Circ. 43424) with the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope from 2026-01-21 03:47 to 07:39 UTC (from 123.6 to 127.5 hours after the trigger) and obtained 99 and 171 minutes of exposure in the r and z filters, respectively. The observing conditions were good. 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 source we have previously reported (Butler et al., GCN Circ 43459; Watson et al., GCN Circ 43480) is clearly detected with preliminary magnitudes of r = 23.09 +/- 0.06, z = 23.10 +/- 0.13. Considering all of our data, the rebrightening we tentatively reported (Watson et al., GCN Circ 43480) is not confirmed and the data seem to be best explained by a simple flattening. We also note that while this source is within the WXT error regions, it is not within the FXT error region (Wang et al., GCN Circ. 43424). We do not consider it to be associated with EP 260116a. 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/43491. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41588] GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
by GCN Circulars 21 Jan '26

21 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43490 SUBJECT: GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765 DATE: 26/01/21 17:54:30 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani(a)nbi.ku.dk> B. Schneider (LAM), A. Saccardi (CEA/Irfu), J. T. Palmerio (CEA/Irfu), S. D. Vergani (LUX-Paris Obs.), D. B. Malesani (DAWN/NBI and Radboud), M. Ferro (INAF/OAB), G. Corcoran (UCD), C. Lachaud (APC), Z.-Y. Lin (APC), report on behalf of the Stargate collaboration: At the position of the optical counterpart (Cheng et al., GCN 42803; Li et al., GCN 42806; Sun et al., GCN 42807; Ma et al., GCN 42811; Gupta et al., GCN 42813; Busman et al., GCN 42814; Volnova et al., GCN 42950) of the high-energy transient GRB 251122A / EP251122a (Wang et al., GCN 42799; Lin et al., GCN 42800), a galaxy is visible in the Legacy survey, with magnitude r ~ 24.6, which is also detected in archival images from the Hyper Suprime-Cam Legacy Archive (Tanaka et al. 2021, doi:10.1093/pasj/psab034) A spectrum of this object was secured using the ESO VLT UT3 (Melipal) equipped with the X-shooter spectrograph. The spectrum covers the wavelength range 3000-25000 AA, and consists of 4 exposures of 1200 s each. The observation mid time is 2025 Dec 23.08 UT (30.5 days after the GRB). A single, very clear emission line is detected at 18140 Å. We discuss its interpretation below. - At the X-shooter resolution we would expect to resolve it if it was the [O II] 3727/3729 doublet (at z = 3.87). While the line is indeed resolved in wavelength space, it does not show a doublet profile; there is also no hint of Lyalpha nor [O III] 5008 in emission at this redshift. - The line cannot be [O III] 5008 (at z = 2.62), otherwise we would also detect [O III] 4959, which is expected from first principles to be ~1/3 as intense, and is excluded by our data. We also do not detect Halpha in the K band, a region clean of atmospheric absorption. - The line is however consistent with Halpha at z = 1.765; at this redshift, both Hbeta and [O III] fall at observed wavelengths with poor atmospheric transmission, and their non-detection is thus not unexpected. The [O II] doublet is not detected at this redshift, although it falls in a noisy region of the spectrum (at the interface between the X-shooter VIS and NIR arms). Dust extinction could also contribute to the faintness of this line. We conclude that z = 1.765 is most likely the redshift of GRB 251122A / EP251122a. We acknowledge excellent support from the observing staff at Paranal, in particular Claudia Cid, Florian Rodler, Jonathan Smoker and Thomas Rivinius. The analysis of this spectrum was carried out with the help of the zHunter tool (https://doi.org/10.5281/zenodo.15189495) View this GCN Circular online at https://gcn.nasa.gov/circulars/43490. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41587] GRB 260120B: Fermi GBM Observation
by GCN Circulars 21 Jan '26

21 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43489 SUBJECT: GRB 260120B: Fermi GBM Observation DATE: 26/01/21 16:21:32 GMT FROM: Matt Godwin <msg0028(a)uah.edu> Matt Godwin (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 18:00:26.05 UT on 20 January 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260120B (trigger 790624831/260120750), which was also detected by Swift BAT (Ferro et al. 2026, GCN 43479), Swift XRT (Goad et al. 2026, GCN 43484), and SVOM/C-GFT (Wu et al. 2026, GCN 43483). The Fermi GBM real-time localization (GCN 43477) is consistent with the Swift BAT position. The angle from the Fermi LAT boresight is 10 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 7 s (50-300 keV). The time-averaged spectrum from T0-1.1 to T0+9.9 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.19 +/- 0.01 and the cutoff energy, parameterized as Epeak, is 214 +/- 4 keV. The event fluence (10-1000 keV) in this time interval is (3.1 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.38 s in the 10-1000 keV band is 5.8 +/- 0.3 ph/s/cm^2. A Band function fits the spectrum equally well with Epeak= 152 +/- 2 keV, alpha = 0.36 +/- 0.02 and beta = -2.26 +/- 0.05. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://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/43489. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41586] EP260105a: GTC/HiPERCAM optical observations
by GCN Circulars 21 Jan '26

21 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43488 SUBJECT: EP260105a: GTC/HiPERCAM optical observations DATE: 26/01/21 16:05:28 GMT FROM: javisansie(a)gmail.com J. Sanchez-Sierras (Radboud), G. Corcoran (UCD), P. G. Jonker (Radboud), D. B. Malesani (DAWN/NBI and Radboud), D. Mata Sanchez (IAC), A. L. Cabrera Lavers (GTC), report on behalf of a larger collaboration: We observed the field of EP260105a (Zhou et al., GCN 43327) with the HiPERCAM instrument attached to the Gran Telescopio Canarias (GTC; La Palma, Spain). The observation simultaneously covered the u, g, r, i and z bands with a total exposure time of 1612 s (150 x 10.75 s), starting on 2026-01-15 at 05:49:40 UT (i.e. 10 days after the trigger). Several sources are detected within the EP/FXT error circle, but comparison with archival i-band imaging from the Hyper Suprime-Cam Legacy Archive (Tanaka et al. 2021, doi:10.1093/pasj/psab034) shows all of them to be pre-existing. We carried out subtraction in the i-band with PyZOGY (Guevel et al. 2021), using the HSC image as a template. The subtraction does not show any new source inside the EP-FXT error region (Zhou et al., GCN 43333) down to a limiting AB magnitude of i > 25.5, not corrected by Galactic extinction. This non-detection is consistent with the others reported by Lipunov et al. (GCN 43328), Corcoran et al. (GCN 43332), Li et al. (GCN 43337) and Busmann et al. (GCN 43345). View this GCN Circular online at https://gcn.nasa.gov/circulars/43488. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41585] EP260105a: GTC/HiPERCAM optical observations
by GCN Circulars 21 Jan '26

21 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43488 SUBJECT: EP260105a: GTC/HiPERCAM optical observations DATE: 26/01/21 16:05:28 GMT FROM: javisansie(a)gmail.com J. Sanchez-Sierras (Radboud), G. Corcoran (UCD), P. G. Jonker (Radboud), D. B. Malesani (DAWN/NBI and Radboud), D. Mata Sanchez (IAC), A. L. Cabrera Lavers (GTC), report on behalf of a larger collaboration: We observed the field of EP260105a (Zhou et al., GCN 43327) with the HiPERCAM instrument attached to the Gran Telescopio Canarias (GTC; La Palma, Spain). The observation simultaneously covered the u, g, r, i and z bands with a total exposure time of 1612 s (150 x 10.75 s), starting on 2026-01-15 at 05:49:40 UT (i.e. 10 days after the trigger). Several sources are detected within the EP/FXT error circle, but comparison with archival i-band imaging from the Hyper Suprime-Cam Legacy Archive (Tanaka et al. 2021, doi:10.1093/pasj/psab034) shows all of them to be pre-existing. We carried out subtraction in the i-band with PyZOGY (Guevel et al. 2021), using the HSC image as a template. The subtraction does not show any new source inside the EP-FXT error region (Zhou et al., GCN 43333) down to a limiting AB magnitude of i > 25.5, not corrected by Galactic extinction. This non-detection is consistent with the others reported by Lipunov et al. (GCN 43328), Corcoran et al. (GCN 43332), Li et al. (GCN 43337) and Busmann et al. (GCN 43345). View this GCN Circular online at https://gcn.nasa.gov/circulars/43488. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41584] GRB 260120B: Swift/UVOT Detection
by GCN Circulars 21 Jan '26

21 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43487 SUBJECT: GRB 260120B: Swift/UVOT Detection DATE: 26/01/21 14:04:46 GMT FROM: Alice Breeveld at MSSL-UCL <a.breeveld(a)ucl.ac.uk> A.A. Breeveld (UCL-MSSL) and M. Ferro (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 260120B 149 s after the BAT trigger (Ferro et al., GCN Circ. 43479). A fading source consistent with the optical counterpart position given by Wu et al., (GCN Circ. 43483) and also the enhanced XRT position (Goad et al., GCN Circ. 43484) is detected in the initial UVOT exposures. Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 149 299 147 18.38 ± 0.06 white 588 776 35 >19.4 v 637 657 19 >17.4 b 563 755 39 >18.7 u 307 557 246 18.80 ± 0.14 w1 686 705 19 >17.4 m2 661 681 19 >17.1 w2 613 633 19 >17.5 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.063 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/43487. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41583] GRB 260120B: COLIBRÍ optical upper limits
by GCN Circulars 21 Jan '26

21 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43486 SUBJECT: GRB 260120B: COLIBRÍ optical upper limits DATE: 26/01/21 03:39:32 GMT FROM: globus(a)astro.unam.mx Noémie Globus (UNAM), Antonio de Ugarte Postigo (LAM), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), 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), 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 Benjamin Schneider (LAM): We imaged the field of the Swift GRB 260120B (Ferro at al., GCN Circ. 43479; Goad et al., GCN Circ. 43484), also detected by Fermi (Fermi GBM team, GCN Circ. 43477) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-01-21 02:00 to 02:19 UTC (from 8.01 to 8.31 hours after the trigger) and obtained 16 minutes of simultaneous exposure in the r and z filters during evening twilight. The data were reduced and coadded 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. We do not detect any source within the enhanced XRT error circle (Goad et al., GCN Circ 43484) down to the following 3-sigma limits: r > 22.87, z > 22.12. We do not detect the afterglow candidate reported by Wu et al (GCN Circ. 43483). This is consistent with the source having faded below our detection limit by the time of our observation, and indicates a temporal index steeper than -1.0. 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/43486. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41582] SVOM GRB260121.06: Global MASTER-Net observations report
by GCN Circulars 21 Jan '26

21 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43485 SUBJECT: SVOM GRB260121.06: Global MASTER-Net observations report DATE: 26/01/21 02:56:37 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-SAAO robotic telescope [1] located in South Africa (South African Astronomical Observatory) started inspect of the SVOM GRB260121.06 (trigger No 1768959043,10h 09m 06.72s , +04d 48m 17.6s, R=1) errorbox 28 sec after notice time and 143 sec after trigger time at 2026-01-21 01:33:06 UT, with upper limit up to 19.7 mag. The observations began at zenith distance = 38 deg. The sun altitude is -24.9 deg. MASTER-OAFA robotic telescope located in Argentina (OAFA observatory of San Juan National University) started inspect of the SVOM GRB260121.06 errorbox 1707 sec after notice time and 1822 sec after trigger time at 2026-01-21 02:01:05 UT, with upper limit up to 19.9 mag. The observations began at zenith distance = 76 deg. The sun altitude is -25.5 deg. The galactic latitude b = 46 deg., longitude l = 236 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3110313 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 159 | 2026-01-21 01:33:06 | MASTER-SAAO | (10h 07m 16.32s , +04d 43m 38.5s) | C | 30 | 19.2 | 159 | 2026-01-21 01:33:06 | MASTER-SAAO | (10h 05m 27.00s , +04d 59m 33.9s) | C | 30 | 19.0 | 213 | 2026-01-21 01:33:55 | MASTER-SAAO | (10h 07m 16.37s , +04d 43m 40.6s) | C | 40 | 19.3 | 213 | 2026-01-21 01:33:55 | MASTER-SAAO | (10h 05m 27.09s , +04d 59m 36.5s) | C | 40 | 19.2 | 277 | 2026-01-21 01:34:54 | MASTER-SAAO | (10h 07m 16.48s , +04d 43m 42.9s) | C | 50 | 19.6 | 277 | 2026-01-21 01:34:54 | MASTER-SAAO | (10h 05m 27.21s , +04d 59m 39.0s) | C | 50 | 19.4 | 351 | 2026-01-21 01:36:03 | MASTER-SAAO | (10h 07m 16.52s , +04d 43m 45.3s) | C | 60 | 19.6 | 351 | 2026-01-21 01:36:03 | MASTER-SAAO | (10h 05m 27.32s , +04d 59m 41.6s) | C | 60 | 19.6 | 430 | 2026-01-21 01:37:22 | MASTER-SAAO | (10h 07m 16.50s , +04d 43m 47.8s) | C | 60 | 19.7 | 430 | 2026-01-21 01:37:23 | MASTER-SAAO | (10h 05m 27.44s , +04d 59m 44.2s) | C | 60 | 19.6 | 509 | 2026-01-21 01:38:41 | MASTER-SAAO | (10h 07m 16.66s , +04d 43m 50.7s) | C | 60 | 19.7 | 509 | 2026-01-21 01:38:41 | MASTER-SAAO | (10h 05m 27.61s , +04d 59m 47.4s) | C | 60 | 19.6 | 588 | 2026-01-21 01:40:00 | MASTER-SAAO | (10h 07m 16.81s , +04d 43m 53.2s) | C | 60 | 19.7 | 588 | 2026-01-21 01:40:00 | MASTER-SAAO | (10h 05m 27.77s , +04d 59m 50.0s) | C | 60 | 19.5 | 667 | 2026-01-21 01:41:20 | MASTER-SAAO | (10h 07m 16.96s , +04d 43m 55.6s) | C | 60 | 19.5 | 667 | 2026-01-21 01:41:20 | MASTER-SAAO | (10h 05m 27.93s , +04d 59m 52.5s) | C | 60 | 19.5 | 746 | 2026-01-21 01:42:39 | MASTER-SAAO | (10h 07m 17.14s , +04d 43m 58.4s) | C | 60 | 19.7 | 746 | 2026-01-21 01:42:39 | MASTER-SAAO | (10h 05m 28.11s , +04d 59m 55.5s) | C | 60 | 19.6 | 825 | 2026-01-21 01:43:58 | MASTER-SAAO | (10h 07m 17.17s , +04d 44m 00.9s) | C | 60 | 19.6 | 825 | 2026-01-21 01:43:58 | MASTER-SAAO | (10h 05m 28.27s , +04d 59m 58.2s) | C | 60 | 19.5 | 904 | 2026-01-21 01:45:17 | MASTER-SAAO | (10h 07m 17.19s , +04d 44m 03.4s) | C | 60 | 19.6 | 904 | 2026-01-21 01:45:17 | MASTER-SAAO | (10h 05m 28.40s , +05d 00m 00.9s) | C | 60 | 19.6 | 983 | 2026-01-21 01:46:36 | MASTER-SAAO | (10h 07m 17.39s , +04d 44m 05.8s) | C | 60 | 19.6 | 983 | 2026-01-21 01:46:36 | MASTER-SAAO | (10h 05m 28.59s , +05d 00m 03.4s) | C | 60 | 19.5 | 1062 | 2026-01-21 01:47:55 | MASTER-SAAO | (10h 07m 17.56s , +04d 44m 08.7s) | C | 60 | 19.7 | 1062 | 2026-01-21 01:47:55 | MASTER-SAAO | (10h 05m 28.76s , +05d 00m 06.5s) | C | 60 | 19.6 | 1142 | 2026-01-21 01:49:14 | MASTER-SAAO | (10h 07m 17.74s , +04d 44m 11.1s) | C | 60 | 19.6 | 1142 | 2026-01-21 01:49:14 | MASTER-SAAO | (10h 05m 28.95s , +05d 00m 08.9s) | C | 60 | 19.5 | 1221 | 2026-01-21 01:50:33 | MASTER-SAAO | (10h 07m 17.92s , +04d 44m 13.6s) | C | 60 | 19.7 | 1221 | 2026-01-21 01:50:33 | MASTER-SAAO | (10h 05m 29.13s , +05d 00m 11.3s) | C | 60 | 19.5 | 1300 | 2026-01-21 01:51:52 | MASTER-SAAO | (10h 07m 18.11s , +04d 44m 16.4s) | C | 60 | 19.6 | 1300 | 2026-01-21 01:51:52 | MASTER-SAAO | (10h 05m 29.32s , +05d 00m 14.0s) | C | 60 | 19.5 | 1379 | 2026-01-21 01:53:11 | MASTER-SAAO | (10h 07m 17.98s , +04d 44m 19.0s) | C | 60 | 19.6 | 1379 | 2026-01-21 01:53:11 | MASTER-SAAO | (10h 05m 29.44s , +05d 00m 16.7s) | C | 60 | 19.5 | 1458 | 2026-01-21 01:54:31 | MASTER-SAAO | (10h 07m 18.15s , +04d 44m 21.6s) | C | 60 | 19.6 | 1458 | 2026-01-21 01:54:31 | MASTER-SAAO | (10h 05m 29.62s , +05d 00m 19.6s) | C | 60 | 19.5 | 1537 | 2026-01-21 01:55:49 | MASTER-SAAO | (10h 07m 18.33s , +04d 44m 24.5s) | C | 60 | 19.7 | 1537 | 2026-01-21 01:55:49 | MASTER-SAAO | (10h 05m 29.81s , +05d 00m 22.7s) | C | 60 | 19.6 | 1616 | 2026-01-21 01:57:08 | MASTER-SAAO | (10h 05m 29.97s , +05d 00m 24.8s) | C | 60 | 19.6 | 1852 | 2026-01-21 02:01:05 | MASTER-OAFA | (10h 09m 19.08s , +04d 45m 04.6s) | C | 60 | 14.8 | 1918 | 2026-01-21 02:02:10 | MASTER-OAFA | (10h 09m 19.20s , +04d 45m 08.9s) | C | 60 | 14.5 | 1984 | 2026-01-21 02:03:17 | MASTER-OAFA | (10h 09m 19.35s , +04d 45m 14.0s) | C | 60 | 14.8 | 2182 | 2026-01-21 02:06:35 | MASTER-OAFA | (10h 09m 19.86s , +04d 45m 30.4s) | C | 60 | 14.8 | 2248 | 2026-01-21 02:07:40 | MASTER-OAFA | (10h 09m 20.05s , +04d 45m 36.7s) | C | 60 | 14.2 | 2313 | 2026-01-21 02:08:46 | MASTER-OAFA | (10h 09m 20.21s , +04d 45m 41.4s) | C | 60 | 15.6 | 2379 | 2026-01-21 02:09:52 | MASTER-OAFA | (10h 09m 20.36s , +04d 45m 46.1s) | C | 60 | 17.2 | 2445 | 2026-01-21 02:10:57 | MASTER-OAFA | (10h 09m 20.47s , +04d 45m 50.5s) | C | 60 | 16.1 | 2511 | 2026-01-21 02:12:03 | MASTER-OAFA | (10h 09m 20.62s , +04d 45m 55.5s) | C | 60 | 13.3 | 2577 | 2026-01-21 02:13:10 | MASTER-OAFA | (10h 09m 20.79s , +04d 46m 01.4s) | C | 60 | 14.9 | 2643 | 2026-01-21 02:14:16 | MASTER-OAFA | (10h 09m 20.87s , +04d 46m 05.5s) | C | 60 | 13.5 | 2840 | 2026-01-21 02:17:32 | MASTER-OAFA | (10h 09m 21.35s , +04d 46m 21.7s) | C | 60 | 14.4 | 3103 | 2026-01-21 02:21:56 | MASTER-OAFA | (10h 09m 21.91s , +04d 46m 40.3s) | C | 60 | 14.9 | 3234 | 2026-01-21 02:24:07 | MASTER-OAFA | (10h 09m 22.15s , +04d 46m 50.2s) | C | 60 | 15.4 | 3300 | 2026-01-21 02:25:12 | MASTER-OAFA | (10h 09m 22.25s , +04d 46m 54.4s) | C | 60 | 17.2 | 3366 | 2026-01-21 02:26:19 | MASTER-OAFA | (10h 09m 22.36s , +04d 46m 59.7s) | C | 60 | 16.6 | 3432 | 2026-01-21 02:27:24 | MASTER-OAFA | (10h 09m 22.43s , +04d 47m 03.4s) | C | 60 | 17.1 | 3498 | 2026-01-21 02:28:30 | MASTER-OAFA | (10h 09m 22.54s , +04d 47m 06.7s) | C | 60 | 15.5 | 3629 | 2026-01-21 02:30:42 | MASTER-OAFA | (10h 09m 22.83s , +04d 47m 18.1s) | C | 60 | 17.1 | 3695 | 2026-01-21 02:31:47 | MASTER-OAFA | (10h 09m 22.90s , +04d 47m 21.4s) | C | 60 | 19.1 | 3760 | 2026-01-21 02:32:53 | MASTER-OAFA | (10h 09m 23.01s , +04d 47m 25.9s) | C | 60 | 18.8 | 3826 | 2026-01-21 02:33:59 | MASTER-OAFA | (10h 09m 23.12s , +04d 47m 30.8s) | C | 60 | 19.1 | 3892 | 2026-01-21 02:35:04 | MASTER-OAFA | (10h 09m 23.23s , +04d 47m 35.2s) | C | 60 | 19.1 | 3958 | 2026-01-21 02:36:11 | MASTER-OAFA | (10h 09m 23.30s , +04d 47m 39.2s) | C | 60 | 19.6 | 4024 | 2026-01-21 02:37:17 | MASTER-OAFA | (10h 09m 23.40s , +04d 47m 43.3s) | C | 60 | 19.4 | 4089 | 2026-01-21 02:38:22 | MASTER-OAFA | (10h 09m 23.48s , +04d 47m 47.2s) | C | 60 | 18.1 | 4156 | 2026-01-21 02:39:28 | MASTER-OAFA | (10h 09m 23.54s , +04d 47m 50.6s) | C | 60 | 15.0 | 4222 | 2026-01-21 02:40:34 | MASTER-OAFA | (10h 09m 23.68s , +04d 47m 56.6s) | C | 60 | 19.3 | 4288 | 2026-01-21 02:41:40 | MASTER-OAFA | (10h 09m 23.74s , +04d 48m 00.0s) | C | 60 | 19.8 | 4354 | 2026-01-21 02:42:46 | MASTER-OAFA | (10h 09m 23.82s , +04d 48m 03.9s) | C | 60 | 19.9 | 4419 | 2026-01-21 02:43:52 | MASTER-OAFA | (10h 09m 23.88s , +04d 48m 07.9s) | C | 60 | 19.8 | 4485 | 2026-01-21 02:44:57 | MASTER-OAFA | (10h 09m 23.96s , +04d 48m 11.7s) | C | 60 | 18.9 | 4551 | 2026-01-21 02:46:03 | MASTER-OAFA | (10h 09m 24.01s , +04d 48m 15.3s) | C | 60 | 18.6 | 4616 | 2026-01-21 02:47:09 | MASTER-OAFA | (10h 09m 24.08s , +04d 48m 19.3s) | C | 60 | 18.8 | 4682 | 2026-01-21 02:48:15 | MASTER-OAFA | (10h 09m 24.14s , +04d 48m 22.9s) | C | 60 | 18.9 | 4750 | 2026-01-21 02:49:22 | MASTER-OAFA | (10h 09m 24.22s , +04d 48m 26.6s) | C | 60 | 19.0 | 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/43485. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41581] GRB 260120B: Enhanced Swift-XRT position
by GCN Circulars 21 Jan '26

21 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43484 SUBJECT: GRB 260120B: Enhanced Swift-XRT position DATE: 26/01/21 01:28:46 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 609 s of XRT Photon Counting mode data and 1 UVOT images for GRB 260120B, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 284.65977, +61.90497 which is equivalent to: RA (J2000): 18h 58m 38.34s Dec (J2000): +61d 54' 17.9" with an uncertainty of 2.3 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at https://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43484. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41580] GRB 260120B: SVOM/C-GFT optical counterpart detection
by GCN Circulars 21 Jan '26

21 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43483 SUBJECT: GRB 260120B: SVOM/C-GFT optical counterpart detection DATE: 26/01/21 01:08:29 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> C. Wu (NAOC), Z. Kang (CHO), L.P. Xin, X.H. Han, P.P. Zhang, X.M. Lu (NAOC), Z.W. Li, Y. Lv (CHO), R.S. Zhang, Y.J. Xiao, Y.L. Qiu, J. Wang, J.S. Deng, L. Huang, J.Y. Wei (NAOC) report on behalf of the SVOM/C-GFT team: We observed the field of GRB 260120B detected by Fermi/GBM(Fermi GBM team, GCN 43477) and Swift/BAT (Ferro et al., GCN 43479) with LATIOS on SVOM/C-GFT. Observa-tions started at 2026-01-20T18:01:29 UTC, ~63 seconds after the trigger. An uncatalogued optical source, compared to Legacy Surveys DR10 Source Catalog, is detected in our images within the localization error circle (Ferro et al., GCN 43479) at: RA (J2000) = 18h58m38.35s = 284.65980 degrees Dec (J2000) = +61d54m18s = 61.90508 degrees with an uncertainty of ~0.5 arcsec. The magnitudes are: | Mid_t-T0(s) | exposure time (s) | band | mag (AB) | mag_err| |-------------|-------------------|------|----------|--------| | 68 | 1x10 | i | 15.74 | 0.04 | | 634 | 6x30 | g | 19.18 | 0.12 | | 854 | 6x30 | r | 19.03 | 0.12 | The brightness decays very rapidly, with the source fading by ~3.4 mag in the i band over 1000 s starting at T0+68 s. The photometry was calibrated against nearby stars in UCAC4 catalogue and no correction for Galactic dust extinction was applied. We thank the observation assistants Hong-Xv Xue and Bo-Wen Li at Jilin observatory for their excellent support. The Chinese Ground Follow-up Telescope (C-GFT) for the SVOM mission is located at Jilin Station, Changchun Observatory, National Astronomical Observatories, CAS. It features two instruments: (1) CATCH at the Cassegrain focus with a 21 arcsec x 21 arcsec FOV for simultaneous g/r/i-band imaging, and (2) LATIOS, a 4k x 4k CMOS camera at the prime focus with a 1.28 deg x 1.28 deg FOV that images in g, r, and i bands via filter switching. View this GCN Circular online at https://gcn.nasa.gov/circulars/43483. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41579] GRB 260120C: Fermi GBM Final Real-time Localization
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43482 SUBJECT: GRB 260120C: Fermi GBM Final Real-time Localization DATE: 26/01/20 23:15:26 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 SHORT GRB At 23:07:06 UT on 20 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260120C (trigger 790643231.34709 / 260120963). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 262.0, Dec = 3.4 (J2000 degrees, equivalent to J2000 17h 27m, 3d 23'), with a statistical uncertainty of 9.3 degrees. The angle from the Fermi LAT boresight is 108.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260120963/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260120963/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260120963/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43482. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41578] GRB 260101A: 239Alferov CubeSat detection
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43481 SUBJECT: GRB 260101A: 239Alferov CubeSat detection DATE: 26/01/20 20:52:27 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> D. Svinkin (Ioffe), D. Frederiks (Ioffe), D. Kapshtan (Geoscan), M. Orlov (Geoscan), V. Bazunova (Geoscan), E. Shchepin (Geoscan), E. Meltsov (Geoscan), K. Starikov (Geoscan, SPbSU), A. Khogoev (Geoscan), A. Razdobarin (SPbAU), and D. Dolmatov (SPbSU), on behalf of the 239Alferov team, report: The long-duration GRB 260101A (Fermi-GBM detection: The Fermi GBM team, GCN 43284; Hristov and Meegan, GCN 43297; Swift-BAT detection: Cenko et al., GCN 43285; Markwardt et al., GCN 43354; SVOM-GRM detection: Yu et al., GCN 43292; GECAM-B detection: Wang et al., GCN 43294; Konus-Wind detection: Svinkin et al., GCN 43389) was detected by 239Alferov 3U CubeSat at about 00:56:30 UT. The burst light curve, as measured by 239Alferov detector, shows a multipeaked structure very similar to that observed by other IPN instruments. The total burst duration duration is ~28 s. The emission is seen up to ~500 keV. The light curve recorded by 239Alferov is available at: http://www.ioffe.ru/LEA/GRBs/GRB260101_T03419/239Alferov/ 239Alferov is an educational 3U CubeSat mission at SSO combining amateur radio and space research objectives. The gamma-ray detector onboard 239Alferov contains a 64x72x15 mm NaI(Tl) scintillator read out by a SiPM array and covers the energy range from ~20 keV to ~1000 keV. The spacecraft is now at a commissioning stage, with scientific observations started in December 2025. Currently, the instrument records count rates in five energy bands: ~20-50 keV, ~50-100 keV, ~100-500 keV, 500-1000 keV, and > 1000 keV, with 1 s temporal resolution. The surveys span a couple of days with about a day-long analysis and maintenance intervals between the observations. The ground segment of the mission utilizes the SONIKS open ground station network. View this GCN Circular online at https://gcn.nasa.gov/circulars/43481. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41577] EP260116a: COLIBRÍ observations of a tentative optical rebrightening
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43480 SUBJECT: EP260116a: COLIBRÍ observations of a tentative optical rebrightening DATE: 26/01/20 18:36:58 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Alan M. Watson (UNAM), Noémie Globus (UNAM), Nathaniel R. Butler (ASU), Antonio de Ugarte Postigo (LAM) Jean-Luc Atteia (IRAP), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), 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 Benjamin Schneider (LAM) report: We observed the field of EP260116a (Wang et al., GCN Circ. 43424) with the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope from 2026-01-20 03:54 to 08:25 UTC (from 99.7 to 104.3 hours after the trigger) and obtained 142 and 198 minutes of exposure in the r and z filters, respectively. Conditions were poor with variable transparency. 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. Compared to our observations on the previous night (Butler et al., GCN Circ 43459), we measure an apparent rebrightening of Delta r = -0.17 +/- 0.11 Delta z = -0.30 +/- 0.21 Individually, these apparent rebrightenings are only at the level of about 1.5 sigma. However, together they point to a possibly more significant result, minimally that the decay seen previously appears to have slowed. Further observations are planned and encouraged. 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/43480. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41576] GRB 260120B: Swift detection of a burst
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43479 SUBJECT: GRB 260120B: Swift detection of a burst DATE: 26/01/20 18:16:31 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> M. Ferro (INAF-OAB), R. Gupta (NASA GSFC), A. Y. Lien (U Tampa), K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 18:00:26 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 260120B (trigger=1442454). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 284.666, +61.912 which is RA(J2000) = 18h 58m 40s Dec(J2000) = +61d 54' 42" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 10 sec. The peak count rate was ~1700 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 18:02:51.6 UT, 145.5 seconds after the BAT trigger. No source was detected in the 2.5-s promptly available image. We are waiting for the full dataset to detect and localise the XRT counterpart. No UVOT data are available at this time. Burst Advocate for this burst is M. Ferro (matteo.ferro AT inaf.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) View this GCN Circular online at https://gcn.nasa.gov/circulars/43479. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41575] Swift GRB260120.75: Global MASTER-Net observations report
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43478 SUBJECT: Swift GRB260120.75: Global MASTER-Net observations report DATE: 26/01/20 18:16:28 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) was pointed to the Swift GRB260120.75 (trigger No 1442454,18h 58m 39.84s , +61d 54m 43.2s, R=0.05) errorbox 277 sec after notice time and 308 sec after trigger time at 2026-01-20 18:05:34 UT, with upper limit up to 17.0 mag. The observations began at zenith distance = 72 deg. The sun altitude is -43.2 deg. The galactic latitude b = 23 deg., longitude l = 92 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3109829 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 399 | MASTER-Kislovodsk | C | 180 | 12.3 | 399 | MASTER-Kislovodsk | C | 180 | 17.0 | 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/43478. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41574] GRB 260120B: Fermi GBM Final Real-time Localization
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43477 SUBJECT: GRB 260120B: Fermi GBM Final Real-time Localization DATE: 26/01/20 18:10:48 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 18:00:26 UT on 20 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260120B (trigger 790624831.046372 / 260120750). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 282.2, Dec = 64.2 (J2000 degrees, equivalent to J2000 18h 48m, 64d 12'), with a statistical uncertainty of 1.5 degrees. The angle from the Fermi LAT boresight is 11.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260120750/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260120750/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260120750/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43477. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41573] EP260119A: Mondy I-Band Observations
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43476 SUBJECT: EP260119A: Mondy I-Band Observations DATE: 26/01/20 18:05:21 GMT FROM: Nicolai Pankov at IKI <colinsergesen(a)gmail.com> N. Pankov (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova (IKI) report on behalf of IKI-GRB-FuN: We observed the field of the EP260119a (Jiang et al., GCN 43447; Cheng et al., GCN 43449) at the redshift of z ~ 5.47 (Corcoran et al., GCN 43469) with the AZT-33IK 1.5-meter telescope of the Mondy observatory. We obtained 45x120 sec total exposure in the I-band, starting on 2026-01-19 at 17:18:42 UT. The afterglow (Fortin et al., GCN 43450; GCN 43455; Eyles-Ferris et al., GCN 43452; Moskvitin & Spiridonova, GCN 43463; Liu et al., GCN 43464; Ma et al., GCN 43466; Zheng et al., GCN 43468; Corcoran et al., GCN 43469; Bochenek & Perley, GCN 43472) is clearly detected in the stacked image. The preliminary photometry and observation details are provided below: Date UT start t-T0 Exp. Filter Mag MagErr. UL (mid,days) (n*s) (3sigma) 2026-01-19 17:18:42 0.74299 45*120 I 20.87 0.11 22.2 The photometry is based on the same stars used by (Moskvitin & Spiridonova, GCN 43463) and has not been corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43476. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41572] Fermi trigger No 790601190: Global MASTER-Net observations report
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43475 SUBJECT: Fermi trigger No 790601190: Global MASTER-Net observations report DATE: 26/01/20 17:16:02 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 GRB260120.48 (trigger No 790601190,02h 33m 50.40s , +52d 51m 00.0s, R=2.66) errorbox 18094 sec after notice time and 18127 sec after trigger time at 2026-01-20 16:28:32 UT, with upper limit up to 18.0 mag. The observations began at zenith distance = 15 deg. The sun altitude is -25.6 deg. The galactic latitude b = -7 deg., longitude l = 139 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3109139 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 18157 | 2026-01-20 16:28:32 | MASTER-Kislovodsk | (02h 09m 49.63s , +52d 59m 30.1s) | C | 60 | 18.0 | 18566 | 2026-01-20 16:35:21 | MASTER-Kislovodsk | (02h 24m 49.14s , +48d 54m 14.6s) | C | 60 | 12.7 | 18566 | 2026-01-20 16:35:21 | MASTER-Kislovodsk | (02h 17m 56.92s , +49d 13m 20.4s) | C | 60 | 18.0 | 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/43475. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41571] Fermi trigger No 790570272: Global MASTER-Net observations report
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43474 SUBJECT: Fermi trigger No 790570272: Global MASTER-Net observations report DATE: 26/01/20 17:15:40 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-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB260120.12 (trigger No 790570272,03h 14m 19.20s , -35d 09m 36.0s, R=1.41) errorbox 133 sec after notice time and 170 sec after trigger time at 2026-01-20 02:53:57 UT, with upper limit up to 20.9 mag. The observations began at zenith distance = 41 deg. The sun altitude is -32.2 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB260120.12 errorbox 50498 sec after notice time and 50534 sec after trigger time at 2026-01-20 16:53:22 UT, with upper limit up to 13.0 mag. The observations began at zenith distance = 78 deg. The sun altitude is -30.1 deg. The galactic latitude b = -58 deg., longitude l = 236 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3108498 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 185 | 2026-01-20 02:53:57 | MASTER-OAFA | (02h 59m 50.02s , -35d 32m 29.5s) | C | 30 | 18.5 | 226 | 2026-01-20 02:54:33 | MASTER-OAFA | (02h 59m 50.06s , -35d 32m 29.0s) | C | 40 | 20.7 | 277 | 2026-01-20 02:55:19 | MASTER-OAFA | (02h 59m 50.12s , -35d 32m 29.0s) | C | 50 | 20.8 | 338 | 2026-01-20 02:56:15 | MASTER-OAFA | (02h 59m 50.21s , -35d 32m 29.0s) | C | 60 | 20.9 | 50565 | 2026-01-20 16:53:22 | MASTER-Kislovodsk | (03h 10m 05.18s , -34d 42m 45.9s) | C | 60 | 13.0 | 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/43474. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41570] GRB 260114A: Swift/UVOT Upper Limits
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43473 SUBJECT: GRB 260114A: Swift/UVOT Upper Limits DATE: 26/01/20 17:04:02 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M.H. Siegel (PSU) and R. A. J. Eyles-Ferris (U Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 260114A 164 s after the BAT trigger (Eyles-Ferris et al., GCN Circ. 43396). No optical afterglow consistent with the XRT position (Beardmore et al., GCN Circ 43412) or the faint red counterpart (Li et al., GCN Circ. 43398; Volnova et al, GCN Circ. 43401) is detected in the initial UVOT exposures. 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 164 848 102 >20.50 v 705 1100 52 >18.44 b 631 824 38 >19.22 u 507 799 136 >19.56 uvw1 755 774 19 >17.70 uvm2 730 750 19 >17.28 uvw2 681 1080 58 >18.59 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.069 in the direction of the burst (Schlegel et al. 1998) View this GCN Circular online at https://gcn.nasa.gov/circulars/43473. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41569] GRB 260114A: Swift/UVOT Upper Limits
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43473 SUBJECT: GRB 260114A: Swift/UVOT Upper Limits DATE: 26/01/20 17:04:02 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M.H. Siegel (PSU) and R. A. J. Eyles-Ferris (U Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 260114A 164 s after the BAT trigger (Eyles-Ferris et al., GCN Circ. 43396). No optical afterglow consistent with the XRT position (Beardmore et al., GCN Circ 43412) or the faint red counterpart (Li et al., GCN Circ. 43398; Volnova et al, GCN Circ. 43401) is detected in the initial UVOT exposures. 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 164 848 102 >20.50 v 705 1100 52 >18.44 b 631 824 38 >19.22 u 507 799 136 >19.56 uvw1 755 774 19 >17.70 uvm2 730 750 19 >17.28 uvw2 681 1080 58 >18.59 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.069 in the direction of the burst (Schlegel et al. 1998) View this GCN Circular online at https://gcn.nasa.gov/circulars/43473. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41568] EP260119a: Liverpool Telescope optical follow-up observations
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43472 SUBJECT: EP260119a: Liverpool Telescope optical follow-up observations DATE: 26/01/20 16:34:32 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 260119a (Jiang et al., GCN 43447, Cheng et al. GCN 43449, Jiang et al. GCN 43465) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 12x100s exposures in the SDSS r and i filters and 11x100s in SDSS z, starting at 2026-01-19 23:58:53 UT, approximately 24 hours after trigger. We report detections in the stacked images in SDSS i and z filters at the position first reported by Fortin et al. GCN 43450 and Eyles-Ferris et al. GCN 43452, as well as a non-detection in the SDSS r filter: MJD (mid) T_mid-T_0 Filter Mag. (AB) 61060.02484 24.37 h r >22.92 61060.03376 24.58 h i 22.06 ± 0.18 61060.04432 24.83 h z 20.85 ± 0.16 The photometry is consistent with measurements taken at similar time by Liu et al. GCN 43464. 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/43472. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41567] GRB 251202A: further radio observations with the VLA
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43471 SUBJECT: GRB 251202A: further radio observations with the VLA DATE: 26/01/20 16:19:41 GMT FROM: Stefano Giarratana at INAF-OAB <s.giarratana(a)ira.inaf.it> S. Giarratana (INAF-OAB), M. Giroletti (INAF-IRA), G. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.), N. Omodei (Stanford Univ.), O. S. Salafia (INAF-OAB), L. Nava (INAF-OAB) At 11:52:30 UT on 2025 December 6 (T_mid = 4.45 days post-burst) and at 11:34:42 UT on 2025 December 11 (T_mid = 9.43 days post-burst) the Karl G. Jansky VLA observed the field of GRB 251202A / EP251202A (Fermi GBM team, GCN 42933, 42957; Einstein Probe team, GCN 42937, GCN 42946; AstroSat CZTI collaboration, GCN 42967; Insight-HXMT team, GCN 42970; SVOM team, GCN 42997) in three bands, with central frequencies of 6, 10 and 15 GHz. The standard 3C286 was used as bandpass and flux density calibrator, while J0818+4222 was used as phase calibrator. From a preliminary analysis, the radio source coincident with GRB 251202A (Giarratana et al., GCN 43128) is detected at all frequencies: ================================================================ T_mid Freq Peak r.m.s. Beam PA [days] [GHz] [uJy/b] [uJy/b] [arcsec^2] [deg] ================================================================ 4.45 6 99 7 1.07x1.02 54 4.45 10 169 7 0.72x0.60 65 4.45 15 296 9 0.45x0.42 34 9.43 6 118 7 1.06x0.95 -76 9.43 10 219 7 0.69x0.58 89 9.43 15 338 8 0.44x0.39 -74 ================================================================ We would like to thank the staff of the VLA for approving, executing, and processing the observations. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. These observations were carried out as part of project SF181027, approved in the framework of the Fermi - NRAO joint program agreement. View this GCN Circular online at https://gcn.nasa.gov/circulars/43471. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41566] Trigger 1442421: Swift detection of HMXB 1A 1118-61
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43470 SUBJECT: Trigger 1442421: Swift detection of HMXB 1A 1118-61 DATE: 26/01/20 15:12:16 GMT FROM: David Palmer at LANL <palmer(a)lanl.gov> S. Dichiara (PSU), R. Gupta (NASA GSFC), J. A. Kennea (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: Swift Trigger 1442421 is due to the currently active source, HMXB 1A 1118-61, which was previously reported in GCN Circulars #43435 and #43442. This source was misidentified on board due to a known race condition in the software, leading to some spurious GCN Notices which did not identify the source name. View this GCN Circular online at https://gcn.nasa.gov/circulars/43470. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41565] EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43469 SUBJECT: EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47 DATE: 26/01/20 09:45:18 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani(a)nbi.ku.dk> G. Corcoran (UCD), A. J. Levan (Radboud and Warwick), D. B. Malesani (DAWN/NBI and Radboud), A. Martin-Carrillo (UCD), R. A. J. Eyles-Ferris (Leicester), P. G. Jonker (Radboud), A. L. Cabrera Lavers (GTC), A. M. García Rodríguez (GTC) report on behalf of a larger collaboration: We observed the optical counterpart (Fortin et al., GCN 43450; Eyles-Ferris et al., GCN 43452; Moskvitin & Spiridonova, GCN 43463; Liu et al., GCN 43464; Ma et al., GCN 43466; Zheng et al., GCN 43468) of the Einstein Probe fast X-ray transient EP260119a (Jiang et al., GCNs 43447, 43465) using the Gran Telescopio Canarias (GTC) equipped with the OSIRIS+ spectrograph. Our observations consisted of 4 exposures of 1200 s each, using grism R1000R and covering the wavelength range 5200-10200 Å. The observation mid time was Jan 20.156 UT (27.5 hr after trigger). In the acquisition image, the target is detected with an AB magnitude z = 21.06 +- 0.10 (mid time 26.8 hr after trigger), calibrated against nearby Pan-STARRS objects and not corrected for Galactic extinction. A trace is well detected in the red part of our spectrum, with a sharp break around 7870 Å. We interpret this as the onset of the Lyman forest at z ~ 5.47. The sharpness of the break indicates a low HI column density. No clear metal lines are identified in the currently available (preliminary) reduction of the spectra. Our spectroscopic measurement of the redshift is in broad agreement with, and refines, the photometric determination reported by COLIBRÍ (Fortin et al., GCN 43455). View this GCN Circular online at https://gcn.nasa.gov/circulars/43469. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41564] EP260119a: KAIT optical observations
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43468 SUBJECT: EP260119a: KAIT optical observations DATE: 26/01/20 08:08:36 GMT FROM: Weikang Zheng at UC Berkeley <weikang(a)berkeley.edu> WeiKang Zheng (UCB), Xuhui Han (NAOC), Pinpin Zhang (NAOC) and Alexei V. Filippenko (UCB) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, observed the field of EP260119a (Jiang et al., GCN 43447; Cheng et al., GCN 43449; Jiang et al., GCN 43465) from 8.13 to 11.55 hours after the burst. A set of 150x60s clear (roughly R) filter images were obtained. We clearly detected the optical afterglow (Fortin et al., GCN 43450; Eyles-Ferris et al., GCN 43452; Lipunov et al., GCN 43454; Fortin et al., GCN 43455; Moskvitin & Spiridonova, GCN 43463; Liu et al., GCN 43464; Ma et al., GCN 43466) in our coadd image. We measure its brightness to be 21.6 +/- 0.2 mag (Vega) at a mid time of 9.84 hours after the burst. View this GCN Circular online at https://gcn.nasa.gov/circulars/43468. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41563] GRB 260120A: Fermi GBM Final Real-time Localization
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43467 SUBJECT: GRB 260120A: Fermi GBM Final Real-time Localization DATE: 26/01/20 04:12:25 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 04:01:54 UT on 20 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260120A (trigger 790574519.95612 / 260120168). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 345.9, Dec = -24.7 (J2000 degrees, equivalent to J2000 23h 03m, -24d 41'), with a statistical uncertainty of 2.5 degrees. The angle from the Fermi LAT boresight is 72.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260120168/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260120168/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260120168/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43467. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41562] EP260119a: SVOM/VT optical observation
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43466 SUBJECT: EP260119a: SVOM/VT optical observation DATE: 26/01/20 03:46:52 GMT FROM: Yinuo Ma <mayn(a)bao.ac.cn> Y. N. Ma, L. P. Xin, Y. L. Qiu, C. Wu, H. L. Li, Z. H. Yao, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team. SVOM/VT performed a Target of Opportunity observation of EP260119a detected by EP/WXT (Jiang et al., GCN 43447; Cheng et al., GCN 43449; Jiang et al., GCN 43465). SVOM/VT began observing the field at 2026-01-19T09:38:01 UTC, 9.404 hours after the trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. With X-band data available, the optical counterpart (Fortin et al., GCN 43450; Eyles-Ferris et al., GCN 43452; Lipunov et al., GCN 43454; Fortin et al., GCN 43455; Moskvitin & Spiridonova, GCN 43463; Liu et al., GCN 43464) was only detected in VT_R band. The magnitudes are: mid time (h) | exposure time (s) | band | mag (AB) -------------|-------------------|------|---------------- 10.704 | 65*50 | VT_B | > 23.4 10.656 | 61*50 | VT_R | 20.86+-0.08 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/43466. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41561] EP260119a: update of EP-FXT follow-up observation
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43465 SUBJECT: EP260119a: update of EP-FXT follow-up observation DATE: 26/01/20 03:17:16 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. H. Jiang (NJU), D. Zhu, K.J. Zhang ,Y.H. Cheng (SWIFAR,YNU), R. X. Hu (WHU)，H. Sun (NAO, CAS) on behalf of the Einstein Probe (EP) team: EP-FXT performed a follow-up observation of EP260119a (detected by EP-WXT, GCN #43447; and followed by COLIBRI telescope, LCO telescope, MASTER-Net observations, SAO RAS and NOT; GCN #43450, GCN #43455, GCN #43452, GCN #43454, GCN #43463, GCN #43464) about 7.5 hours after the WXT detection, with an exposure time of 6.0 ks. The FXT telemetry data show that an uncatalogued source was detected within the WXT error circle at R.A. = 158.1047, DEC = 65.4975 (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic, reported by Cheng et al ., GCN #43449). The FXT X-ray spectrum of this uncatalogued source can be fitted with an absorbed powerlaw with a hydrogen column density fixed at the Galactic value of 1.20 x 10^20 cm^-2 and a photon index of 1.99 (+/- 0.13). The derived unabsorbed 0.5-10 keV flux is approximately 5.69 (+0.60/-0.55) x 10^-13 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/43465. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41560] EP260119a: NOT optical observations
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43464 SUBJECT: EP260119a: NOT optical observations DATE: 26/01/20 02:54:49 GMT FROM: liuxing(a)nao.cas.cn X. Liu, S.Q. Jiang, J. An, L.B. He, Z.P. Zhu, D. Xu (NAOC), S.Y. Fu (HUST), J.P.U. Fynbo (DAWN/NBI), K. Valeckas (NOT) report on behalf of a large collaboration: We observed the field of EP260119a (Jiang et al., GCN43447; Cheng et al., GCN43449) using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations started at 23:11:51.27 UT on 2026-01-19, i.e., 22.97 hr after the EP trigger, and we obtained 6 x 300 s frames in the Sloan i- and z- bands, respectively . The reported optical counterpart (Fortin et al., GCN43450; GCN 43455; Eyles-Ferris et al., GCN 43454; Moskvitin et al., GCN 43453) was detected in our stacked images in both i- and z- bands. Preliminary photometric results are as follows: T-mid (hr) | Filter | Exposure | Mag 23.80 | i | 6x300s | 21.85 +/- 0.06 23.24 | z | 6x300s | 20.94 +/- 0.08 calibrated with nearby Pan-STARRS1 DR2 stars without the Galactic extinction correction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43464. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41559] EP260119a: SAO RAS optical observations
by GCN Circulars 20 Jan '26

20 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43463 SUBJECT: EP260119a: SAO RAS optical observations DATE: 26/01/20 00:19:23 GMT FROM: Alexander Moskvitin at SAO RAS <mosk(a)sao.ru> A. S. Moskvitin and O. I. Spiridonova (SAO RAS) report on behalf of GRB follow-up team. We observed the field of the EP260119a (Jiang et al., GCN 43447; Cheng et al., GCN 43449) with the Zeiss-1000 1m telescope of the SAO RAS equipped with the CCD photometer. We obtained 8 x 300 sec in Ic band on on Jan. 19, 21:33:52--22:18:23 UT (t_mid - T0 = 0.90439 days). The OT (Fortin et al., GCN 43450; GCN 43455; Eyles-Ferris et al., GCN 43452) is clearly detected in our stacked frame with the brightness of I = 20.8 +/- 0.1 (I_lim = 22.0). This preliminary photometry is based on several nearby SDSS stars (I-magnitudes obtained with Lupton 2005 transformation) and is not corrected for the Galactic extinction. Magnitudes is in Vega system. View this GCN Circular online at https://gcn.nasa.gov/circulars/43463. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41558] SVOM GRB260119.92: Global MASTER-Net observations report
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43462 SUBJECT: SVOM GRB260119.92: Global MASTER-Net observations report DATE: 26/01/19 23:42:41 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) started inspect of the SVOM GRB260119.92 (trigger No 1768860656,11h 26m 01.66s , +61d 23m 16.8s, R=1) errorbox 391 sec after notice time and 436 sec after trigger time at 2026-01-19 22:18:12 UT, with upper limit up to 19.6 mag. The observations began at zenith distance = 19 deg. The sun altitude is -24.8 deg. The galactic latitude b = 53 deg., longitude l = 139 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3108068 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 467 | 2026-01-19 22:18:12 | MASTER-Tunka | (11h 18m 02.89s , +62d 30m 22.3s) | C | 60 | 19.6 | 467 | 2026-01-19 22:18:12 | MASTER-Tunka | (11h 16m 31.83s , +62d 39m 17.8s) | C | 60 | 19.3 | 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/43462. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41557] SVOM GRB260119.92: Global MASTER-Net observations report
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43461 SUBJECT: SVOM GRB260119.92: Global MASTER-Net observations report DATE: 26/01/19 23:42:34 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) started inspect of the SVOM GRB260119.92 (trigger No 1768860172,08h 23m 32.59s , +57d 17m 44.5s, R=1) errorbox 708 sec after notice time and 838 sec after trigger time at 2026-01-19 22:16:50 UT, with upper limit up to 19.4 mag. The observations began at zenith distance = 40 deg. The sun altitude is -25.0 deg. The galactic latitude b = 35 deg., longitude l = 160 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3108061 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 869 | 2026-01-19 22:16:50 | MASTER-Tunka | (08h 21m 45.46s , +57d 40m 30.1s) | C | 60 | 19.4 | 869 | 2026-01-19 22:16:50 | MASTER-Tunka | (08h 20m 28.54s , +57d 48m 24.1s) | C | 60 | 18.9 | 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/43461. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41556] SVOM GRB260119.90: Global MASTER-Net observations report
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43460 SUBJECT: SVOM GRB260119.90: Global MASTER-Net observations report DATE: 26/01/19 22:14:22 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-Tunka robotic telescope [1] located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the SVOM GRB260119.90 (trigger No 1768858916,00h 49m 46.66s , +45d 01m 16.7s, R=1) errorbox 211 sec after notice time and 323 sec after trigger time at 2026-01-19 21:47:19 UT, with upper limit up to 16.8 mag. The observations began at zenith distance = 84 deg. The sun altitude is -29.7 deg. The galactic latitude b = -18 deg., longitude l = 123 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3108046 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 334 | 2026-01-19 21:47:19 | MASTER-Tunka | (00h 49m 43.25s , +45d 13m 31.9s) | C | 20 | 16.7 | 355 | 2026-01-19 21:47:43 | MASTER-Tunka | (00h 49m 43.34s , +45d 13m 38.0s) | C | 15 | 16.7 | 371 | 2026-01-19 21:48:01 | MASTER-Tunka | (00h 49m 43.26s , +45d 13m 33.8s) | C | 10 | 16.6 | 384 | 2026-01-19 21:48:15 | MASTER-Tunka | (00h 49m 43.25s , +45d 13m 27.7s) | C | 10 | 16.5 | 398 | 2026-01-19 21:48:29 | MASTER-Tunka | (00h 49m 43.20s , +45d 13m 41.8s) | C | 10 | 16.6 | 398 | 2026-01-19 21:48:29 | MASTER-Tunka | (00h 49m 19.71s , +45d 19m 14.6s) | C | 10 | 16.4 | 412 | 2026-01-19 21:48:42 | MASTER-Tunka | (00h 49m 43.11s , +45d 13m 46.0s) | C | 10 | 16.6 | 425 | 2026-01-19 21:48:56 | MASTER-Tunka | (00h 49m 43.18s , +45d 13m 28.1s) | C | 10 | 16.6 | 439 | 2026-01-19 21:49:09 | MASTER-Tunka | (00h 49m 43.10s , +45d 13m 28.8s) | C | 10 | 16.7 | 452 | 2026-01-19 21:49:23 | MASTER-Tunka | (00h 49m 43.14s , +45d 13m 39.3s) | C | 10 | 16.7 | 466 | 2026-01-19 21:49:37 | MASTER-Tunka | (00h 49m 43.13s , +45d 13m 33.2s) | C | 10 | 16.6 | 483 | 2026-01-19 21:49:50 | MASTER-Tunka | (00h 49m 43.02s , +45d 13m 44.9s) | C | 15 | 16.8 | 501 | 2026-01-19 21:50:09 | MASTER-Tunka | (00h 49m 43.11s , +45d 13m 32.9s) | C | 15 | 16.8 | 520 | 2026-01-19 21:50:27 | MASTER-Tunka | (00h 49m 43.08s , +45d 13m 32.3s) | C | 15 | 16.8 | 538 | 2026-01-19 21:50:46 | MASTER-Tunka | (00h 49m 43.08s , +45d 13m 33.7s) | C | 15 | 16.8 | 554 | 2026-01-19 21:51:05 | MASTER-Tunka | (00h 49m 43.03s , +45d 13m 55.1s) | C | 10 | 16.7 | 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/43460. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41555] EP 260116a: COLIBRÍ detection of a fading optical source
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43459 SUBJECT: EP 260116a: COLIBRÍ detection of a fading optical source DATE: 26/01/19 21:20:37 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Nathaniel R. Butler (ASU), Noémie Globus (UNAM), Alan M. Watson (UNAM), Jean-Luc Atteia (IRAP), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), 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), Benjamin Schneider (LAM), and Antonio de Ugarte Postigo (LAM) report: We observed the field of EP 260116a (Wang et al., GCN Circ. 43424) obtained with the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope on the nights of 2026 January 17, 18, and 19 UTC at median times of 30.8, 52.4, and 78.7 hours after the trigger and obtained 80, 96, and 128 minutes, respectively, 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. We reported preliminary results from the first night in Magnani et al. (GCN Circ. 43436). In contrast to our initial analysis, a refined reprocessing and the subsequent follow up observations have revealed a fading optical source located within the EP/WXT error region (Wang et al., GCN Circ. 43424) at the coordinates RA = 07:35:14.14, Dec = +06:20:14.3 (J2000). At the last epoch, we measure preliminary magnitudes of r = 23.22 +/- 0.06, z = 22.81 +/- 0.14. Including these observations together with the two earlier epochs, we model the temporal evolution of the source flux with a power-law decay. We find Flux_r = t^(−0.33 +/- 0.12) and Flux_z = t^(-0.53 +/- 0.23). The source therefore exhibits a slow but consistent decay, which is statistically significant and supports its interpretation as the fading optical counterpart of EP 260116a. No existing source is visible at this position in the PS1 images. Further observations are planned. 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/43459. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41554] GRB 251208D: SVOM/ECLAIRs refined analysis
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43458 SUBJECT: GRB 251208D: SVOM/ECLAIRs refined analysis DATE: 26/01/19 20:59:19 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> H. Yang, O. Godet (IRAP), F. Daigne (IAP), Z.-Y. Lin, F. Cangemi (APC) Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of the possible faint burst GRB 251208D (SVOM burst-id sb25120806, GCN 43032) detected at T0 = 2025-12-08T16:51:43 UT. The burst that triggered ECLAIRs shows a featureless light curve, and is detected from T0-82 s to T0 in the 8-120 keV energy band. The time-averaged spectrum from T0-82 s to T0 in the 8-120 keV is well fitted by a power-law model with a photon index of 1.8+/-0.4 and a corresponding 4-120 keV fluence of (1.1+/-0.3)e-6 erg/cm^2. All the quoted errors are at the 68% confidence level. 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. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs point of contact for this burst is: Hui Yang (IRAP) (hui.yang(a)irap.omp.eu) View this GCN Circular online at https://gcn.nasa.gov/circulars/43458. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41553] GRB 251208D: SVOM/ECLAIRs refined analysis
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43457 SUBJECT: GRB 251208D: SVOM/ECLAIRs refined analysis DATE: 26/01/19 20:58:08 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> H. Yang, O. Godet (IRAP), F. Daigne (IAP), Z.-Y. Lin, F. Cangemi (APC) Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of the possible faint burst GRB 251208D (SVOM burst-id sb25120806, GCN 43032) detected at T0 = 2025-12-08T16:51:43 UT. The burst that triggered ECLAIRs shows a featureless light curve, and is detected from T0-82 s to T0 in the 8-120 keV energy band. The time-averaged spectrum from T0-82 s to T0 in the 8-120 keV is well fitted by a power-law model with a photon index of 1.8+/-0.4 and a corresponding 4-120 keV fluence of (1.1+/-0.3)e-6 erg/cm^2. All the quoted errors are at the 68% confidence level. 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. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs point of contact for this burst is: Hui Yang (IRAP) (hui.yang(a)irap.omp.eu) View this GCN Circular online at https://gcn.nasa.gov/circulars/43457. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41552] GRB 251208D: SVOM/ECLAIRs refined analysis
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43457 SUBJECT: GRB 251208D: SVOM/ECLAIRs refined analysis DATE: 26/01/19 20:58:08 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> H. Yang, O. Godet (IRAP), F. Daigne (IAP), Z.-Y. Lin, F. Cangemi (APC) Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of the possible faint burst GRB 251208D (SVOM burst-id sb25120806, GCN 43032) detected at T0 = 2025-12-08T16:51:43 UT. The burst that triggered ECLAIRs shows a featureless light curve, and is detected from T0-82 s to T0 in the 8-120 keV energy band. The time-averaged spectrum from T0-82 s to T0 in the 8-120 keV is well fitted by a power-law model with a photon index of 1.8+/-0.4 and a corresponding 4-120 keV fluence of (1.1+/-0.3)e-6 erg/cm^2. All the quoted errors are at the 68% confidence level. 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. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs point of contact for this burst is: Hui Yang (IRAP) (hui.yang(a)irap.omp.eu) View this GCN Circular online at https://gcn.nasa.gov/circulars/43457. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41551] GRB 260117A: Swift-XRT afterglow detection
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43456 SUBJECT: GRB 260117A: Swift-XRT afterglow detection DATE: 26/01/19 20:06:20 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> C. Salvaggio (INAF-OAB), M. Ferro (INAF-OAB), R. Brivio (INAF-OAB), D.N. Burrows (PSU), S. Lanava (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has conducted further observations of the field of the SVOM/ECLAIRs-detected burst GRB 260117A. The observations now extend from T0+12.5 ks to T0+153.1 ks and have a total exposure time of 5.7 ks. Of the sources previously reported, "Source 1" is fading with >3-sigma significance, and is therefore likely the GRB afterglow. Using 1064 s of PC mode data and 1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 188.13864, +43.91274 which is equivalent to: RA (J2000): 12h 32m 33.27s Dec(J2000): +43d 54' 45.9" with an uncertainty of 4.9 arcsec (radius, 90% confidence). This position is 2.5 arcmin from the SVOM/ECLAIRs position, and 0.2 arcsec from the SVOM/VT optical candidate reported in GCN Circ. 43411. The source is fading with alpha >0.2. The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/00021898. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021898. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43456. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41550] EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43455 SUBJECT: EP260119a: COLIBRÍ photometric redshift z ≈ 5.6 DATE: 26/01/19 18:02:49 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Francis Fortin (IRAP), Leonardo García García (UNAM), Camila Angulo (UNAM), Nikos Mandarakas (LAM), Alan M. Watson (UNAM), Jean-Grégoire Ducoin (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Asuka Kuwata (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), and Antonio de Ugarte Postigo (LAM) report: We imaged the field of EP260119a (Jiang et al., GCN Circ. 43447; Cheng et al., GCN CIrc. 43449) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-01-19 09:00 to 13:37 UTC (from 8.7 to 13.4 hours after the trigger) and obtained 105, 53, 97, and 32 minutes of exposure in the r, i, z, and y filters. The data were reduced and coadded 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. Our longer time interval and multi-filter photometry allows us to estimate the decay index and the photometric redshift of the optical counterpart reported by ourselves in Fortin et al. (GCN Circ. 43450) and confirmed by Eyles-Ferris et al. (GCN Circ 43452). In the z band, we see a shallow decay with a temporal index of -0.44 +/- 0.19. The counterpart is detected in all four bands. After correcting for the Galactic foreground extinction corresponding to a reddening of E(B-V) = 0.011 mag (Schlafly & Finkbeiner 2011) and fitting a power-law model to the rizy-bands using a no dust extinction curve, we derive a photometric redshift of z = 5.62 with formal errors of +0.02-0.03 (1-sigma c.l.). We caution that our magnitudes are not strictly simultaneous, but nevertheless the break from z to i to r is much stronger than can be accounted for by this effect. 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/43455. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41549] EP260119a: Global MASTER-Net observations report
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43454 SUBJECT: EP260119a: Global MASTER-Net observations report DATE: 26/01/19 17:36:27 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 EP260119a ( EP Team et al., GCN 43447) errorbox 32012 sec after notice time and 60248 sec after trigger time at 2026-01-19 16:57:56 UT, with upper limit up to 20.4 mag. The observations began at zenith distance = 26 deg. The sun altitude is -59.1 deg. The galactic latitude b = 46 deg., longitude l = 143 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3107348 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 60279 | 2026-01-19 16:57:56 | MASTER-Tunka | (10h 31m 16.45s , +66d 08m 29.3s) | C | 60 | 20.3 | 60279 | 2026-01-19 16:57:56 | MASTER-Tunka | (10h 29m 47.72s , +66d 16m 01.1s) | C | 60 | 20.0 | 60352 | 2026-01-19 16:59:09 | MASTER-Tunka | (10h 31m 09.89s , +66d 07m 36.5s) | C | 60 | 20.4 | 60352 | 2026-01-19 16:59:09 | MASTER-Tunka | (10h 29m 41.26s , +66d 15m 08.6s) | C | 60 | 20.0 | 60427 | 2026-01-19 17:00:24 | MASTER-Tunka | (10h 31m 09.54s , +66d 08m 35.2s) | C | 60 | 20.3 | 60427 | 2026-01-19 17:00:24 | MASTER-Tunka | (10h 29m 40.79s , +66d 16m 07.0s) | C | 60 | 20.0 | 60507 | 2026-01-19 17:01:44 | MASTER-Tunka | (10h 31m 15.00s , +66d 07m 33.2s) | C | 60 | 20.4 | 60507 | 2026-01-19 17:01:44 | MASTER-Tunka | (10h 29m 46.20s , +66d 15m 05.6s) | C | 60 | 19.9 | 60580 | 2026-01-19 17:02:57 | MASTER-Tunka | (10h 31m 07.97s , +66d 06m 32.0s) | C | 60 | 20.4 | 60580 | 2026-01-19 17:02:57 | MASTER-Tunka | (10h 29m 39.21s , +66d 14m 03.9s) | C | 60 | 19.9 | 60653 | 2026-01-19 17:04:11 | MASTER-Tunka | (10h 31m 13.12s , +66d 06m 55.4s) | C | 60 | 20.4 | 60653 | 2026-01-19 17:04:11 | MASTER-Tunka | (10h 29m 44.32s , +66d 14m 27.1s) | C | 60 | 20.0 | 60729 | 2026-01-19 17:05:27 | MASTER-Tunka | (10h 31m 10.06s , +66d 08m 03.1s) | C | 60 | 20.4 | 60729 | 2026-01-19 17:05:27 | MASTER-Tunka | (10h 29m 41.17s , +66d 15m 34.4s) | C | 60 | 20.0 | 60815 | 2026-01-19 17:06:52 | MASTER-Tunka | (10h 31m 09.77s , +66d 06m 47.2s) | C | 60 | 20.3 | 60815 | 2026-01-19 17:06:52 | MASTER-Tunka | (10h 29m 40.81s , +66d 14m 18.8s) | C | 60 | 19.9 | 60887 | 2026-01-19 17:08:05 | MASTER-Tunka | (10h 31m 13.15s , +66d 08m 15.5s) | C | 60 | 20.4 | 60887 | 2026-01-19 17:08:05 | MASTER-Tunka | (10h 29m 44.02s , +66d 15m 47.0s) | C | 60 | 20.0 | 60961 | 2026-01-19 17:09:18 | MASTER-Tunka | (10h 31m 05.28s , +66d 07m 24.6s) | C | 60 | 20.4 | 60961 | 2026-01-19 17:09:18 | MASTER-Tunka | (10h 29m 36.21s , +66d 14m 55.7s) | C | 60 | 20.0 | 61036 | 2026-01-19 17:10:34 | MASTER-Tunka | (10h 31m 05.02s , +66d 08m 23.0s) | C | 60 | 20.4 | 61036 | 2026-01-19 17:10:34 | MASTER-Tunka | (10h 29m 35.82s , +66d 15m 54.2s) | C | 60 | 20.0 | 61111 | 2026-01-19 17:11:48 | MASTER-Tunka | (10h 31m 11.19s , +66d 07m 21.5s) | C | 60 | 20.4 | 61111 | 2026-01-19 17:11:49 | MASTER-Tunka | (10h 29m 41.99s , +66d 14m 52.8s) | C | 60 | 19.9 | 61186 | 2026-01-19 17:13:04 | MASTER-Tunka | (10h 31m 05.60s , +66d 06m 19.1s) | C | 60 | 20.4 | 61186 | 2026-01-19 17:13:04 | MASTER-Tunka | (10h 29m 36.47s , +66d 13m 50.5s) | C | 60 | 20.0 | 61262 | 2026-01-19 17:14:19 | MASTER-Tunka | (10h 31m 09.69s , +66d 06m 22.9s) | C | 60 | 20.4 | 61262 | 2026-01-19 17:14:19 | MASTER-Tunka | (10h 29m 40.43s , +66d 13m 54.9s) | C | 60 | 20.0 | 61335 | 2026-01-19 17:15:33 | MASTER-Tunka | (10h 31m 06.90s , +66d 07m 57.6s) | C | 60 | 20.4 | 61335 | 2026-01-19 17:15:33 | MASTER-Tunka | (10h 29m 37.54s , +66d 15m 48.4s) | C | 60 | 19.7 | 61409 | 2026-01-19 17:16:47 | MASTER-Tunka | (10h 31m 06.53s , +66d 06m 43.7s) | C | 60 | 20.3 | 61409 | 2026-01-19 17:16:47 | MASTER-Tunka | (10h 29m 37.16s , +66d 14m 35.6s) | C | 60 | 19.9 | 61483 | 2026-01-19 17:18:00 | MASTER-Tunka | (10h 31m 08.49s , +66d 07m 46.8s) | C | 60 | 20.3 | 61483 | 2026-01-19 17:18:00 | MASTER-Tunka | (10h 29m 38.92s , +66d 15m 38.1s) | C | 60 | 20.0 | 61558 | 2026-01-19 17:19:15 | MASTER-Tunka | (10h 31m 03.24s , +66d 07m 11.2s) | C | 60 | 20.4 | 61558 | 2026-01-19 17:19:16 | MASTER-Tunka | (10h 29m 33.66s , +66d 15m 02.3s) | C | 60 | 20.0 | 61631 | 2026-01-19 17:20:28 | MASTER-Tunka | (10h 31m 03.39s , +66d 08m 09.2s) | C | 60 | 20.4 | 61631 | 2026-01-19 17:20:28 | MASTER-Tunka | (10h 29m 33.60s , +66d 16m 00.6s) | C | 60 | 19.9 | 61703 | 2026-01-19 17:21:41 | MASTER-Tunka | (10h 29m 38.69s , +66d 14m 59.2s) | C | 60 | 20.0 | 61703 | 2026-01-19 17:21:41 | MASTER-Tunka | (10h 31m 08.49s , +66d 07m 07.4s) | C | 60 | 20.4 | 61777 | 2026-01-19 17:22:55 | MASTER-Tunka | (10h 31m 01.86s , +66d 06m 05.4s) | C | 60 | 20.4 | 61777 | 2026-01-19 17:22:55 | MASTER-Tunka | (10h 29m 32.07s , +66d 13m 57.0s) | C | 60 | 19.9 | 61852 | 2026-01-19 17:24:09 | MASTER-Tunka | (10h 31m 08.12s , +66d 06m 25.5s) | C | 60 | 20.3 | 61852 | 2026-01-19 17:24:09 | MASTER-Tunka | (10h 29m 38.21s , +66d 14m 17.5s) | C | 60 | 19.9 | 61925 | 2026-01-19 17:25:23 | MASTER-Tunka | (10h 31m 04.08s , +66d 07m 59.9s) | C | 60 | 20.4 | 61926 | 2026-01-19 17:25:23 | MASTER-Tunka | (10h 29m 34.06s , +66d 15m 51.6s) | C | 60 | 19.9 | 61999 | 2026-01-19 17:26:36 | MASTER-Tunka | (10h 31m 03.79s , +66d 06m 09.1s) | C | 60 | 20.4 | 61999 | 2026-01-19 17:26:36 | MASTER-Tunka | (10h 29m 33.75s , +66d 14m 01.0s) | C | 60 | 19.9 | 62072 | 2026-01-19 17:27:49 | MASTER-Tunka | (10h 31m 06.81s , +66d 07m 44.6s) | C | 60 | 20.4 | 62072 | 2026-01-19 17:27:49 | MASTER-Tunka | (10h 29m 36.65s , +66d 15m 36.3s) | C | 60 | 20.0 | 62145 | 2026-01-19 17:29:03 | MASTER-Tunka | (10h 30m 59.37s , +66d 06m 57.6s) | C | 60 | 20.4 | 62145 | 2026-01-19 17:29:03 | MASTER-Tunka | (10h 29m 29.23s , +66d 14m 49.2s) | C | 60 | 20.0 | 62225 | 2026-01-19 17:30:23 | MASTER-Tunka | (10h 31m 00.13s , +66d 07m 55.9s) | C | 60 | 20.4 | 62225 | 2026-01-19 17:30:23 | MASTER-Tunka | (10h 29m 29.89s , +66d 15m 47.5s) | C | 60 | 19.9 | 62299 | 2026-01-19 17:31:37 | MASTER-Tunka | (10h 31m 06.28s , +66d 06m 54.1s) | C | 60 | 20.4 | 62299 | 2026-01-19 17:31:37 | MASTER-Tunka | (10h 29m 36.01s , +66d 14m 45.6s) | C | 60 | 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/43454. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41548] GRB 260115A: AstroSat CZTI detection
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43453 SUBJECT: GRB 260115A: AstroSat CZTI detection DATE: 26/01/19 16:33:28 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> A. Arya (IITB), A. Goyal (IITB), M. Tembhurnikar (IUCAA), S. Salunke (IUCAA), Harsha K. H. (IUCAA), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a GRB 260115A which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 43417), and GECAM-B (Zhang et. al., GCN Circ. 43434). The source was faintly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2026-01-15 17:46:47.72 UTC. The measured peak count rate associated with the burst is 252 (+64, -69) counts/s above the background in the combined data of all quadrants, with a total of 270 (+117, -120) counts. The local mean background count rate was 1327 (+9, -12) counts/s. Due to the intrinsic 1 s binning of veto data, we cannot reliably estimate a T90 for our detection. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/43453. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41547] EP260119a: LCO optical observations
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43452 SUBJECT: EP260119a: LCO optical observations DATE: 26/01/19 13:02:37 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani(a)nbi.ku.dk> R. A. J. Eyles-Ferris (Leicester), J. A. Quirola-Vasquez (Radboud), G. Corcoran (UCD), D. B. Malesani (DAWN-NBI and Radboud), A. van Hoof (Radboud), A. Martin-Carrillo (UCD), P. G. Jonker (Radboud), A. J. Levan (Radboud and Warwick) report on behalf of a larger group: We observed the field of the fast X-ray transient EP260119a (Jiang et al., GCN 43447; Cheng et al., GCN 43449) using an LCO 1m telescope located at the McDonald Observatory (Texas, USA) equipped with the SINISTRO instrument. A series of 3x300 s exposures was taken in each of the SDSS-r and SDSS-z filters, starting on 2026-01-19 at 09:40:45 UT (9.45 hr after the trigger). The optical counterpart discovered by COLIBRÍ (Fortin et al., GCN 43450) is detected in our images, with magnitudes: r = 22.83 +- 0.33 (9.54 hr after trigger) z = 20.26 +- 0.13 (9.81 hr after trigger) These values are in the AB system, are calibrated against the Pan-STARRS survey, and are not corrected for Galactic extinction. Our measurements confirm the red r-z color of the afterglow (Fortin et al., GCN 43450). No host galaxy is detected in the r band in a stack of archival CFHT images, down to a limiting magnitude r > 24.5. View this GCN Circular online at https://gcn.nasa.gov/circulars/43452. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41546] GRB 260117A: ZTSh optical upper limit
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43451 SUBJECT: GRB 260117A: ZTSh optical upper limit DATE: 26/01/19 11:53:13 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. A. Volnova (IKI), V. Rumyantsev (CrAO), N. Pankov (HSE, IKI), A. S. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We observed the field of the SVOM GRB 260117A (Palmerio et al., GCN Circ. 43437) with the ZTSH telescope of CrAO starting on 2026-01-18 at 20:50:34 UT and taking several 120s exposures in R-band. At the position of the source detected by Swift/XRT (Salvaggio et al., GCN 43439; Evans et al., GCN 43438) we do not detect the optical source reported previously by SVOM/VT (Li et al., GCN Circ. 43441) and SVOM/COLIBRÍ (FM-GFT; Fortin et al., GCN 43445). Preliminary photometry is the following: Date UT start t-T0 Exp. Filter Obj. Err. UL Site/Telescope (mid,days) (n*s) (3sigma) 2026-01-18 20:50:34 1.07354 37*120 R n/d n/d 23.2 CrAO/ZTSh The photometry is based on nearby stars from the USNO-B1 catalogue (R2 magnitudes) and is not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43451. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41545] EP260119a: COLIBRÍ optical counterpart candidate
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43450 SUBJECT: EP260119a: COLIBRÍ optical counterpart candidate DATE: 26/01/19 11:36:14 GMT FROM: F. Fortin at IRAP <ffortin.sci.edu(a)gmail.com> Francis Fortin (IRAP), Leonardo García García (UNAM), Jean-Grégoire Ducoin (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM), Fredd Sánchez Álvarez (UNAM), and Antonio de Ugarte Postigo (LAM): We imaged the field of EP260119a (Jiang et al., GCN Circ. 43447) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-01-19T09:00:10 to 09:43:40 UTC (from 8.7 to 9.5 hours after the trigger) and obtained 32 minutes of simultaneous exposure in the r and z filters. The data were reduced and coadded with the COLIBRÍ pipelines and analysed 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. We detect an uncatalogued source (revealed by image subtraction using PanSTARRS as template) and consistent with the WXT 2.3 arcmin error circle and located 8 arcsec away from the FXT position (20 arcsec error circle, Cheng et al., GCN Circ 43449) at: RA(J2000) = 10:32:24.4 = 158.1018 degrees Dec(J2000) = +65:29:44.2 = +65.4956 degrees with an uncertainty of 0.5 arcsec. The preliminary magnitudes for this source are: r = 23.02 +/- 0.14 z = 20.08 +/- 0.03 This source is a good candidate for being the optical counterpart of EP260119a, and we encourage further observations to confirm its nature. We also note that the candidate is very red, which could indicate a source located at high redshift. Further observations with COLIBRÍ are ongoing. 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/43450. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41544] EP260119a: preliminary result from the EP-FXT observation
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43449 SUBJECT: EP260119a: preliminary result from the EP-FXT observation DATE: 26/01/19 09:24:28 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y.H. Cheng (SWIFAR,YNU), Y. H. Jiang (NJU), D. Zhu, K.J. Zhang (SWIFAR,YNU), R. X. Hu (WHU)，H. Sun (NAO, CAS) report on behalf of the Einstein Probe team We performed a follow-up observation of EP260119a (detected by EP-WXT Jiang et al ., GCN #43447 ), with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission. The observation began at 2026-01-19T07:21:31 UTC, about 7 hours after the detection. The FXT onboard alert shows that one uncatalogued source was detected by both FXT-A and FXT-B. The position of the source is R.A. = 158.1047 deg, DEC = 65.4975 deg, (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). The estimated flux in the 0.5-10 keV band inferred from the alert information is around 5.0 x 10^-13 erg/cm^2/s. More information will be updated when the telemetry data is received. 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). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES. View this GCN Circular online at https://gcn.nasa.gov/circulars/43449. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41543] GRB 260110A: SVOM detection of a burst through offline search
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43448 SUBJECT: GRB 260110A: SVOM detection of a burst through offline search DATE: 26/01/19 08:24:17 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> M. Brunet, O. Godet (IRAP), N. Dagoneau (CEA) report on behalf of the SVOM team: The SVOM/ECLAIRs telescope detected a transient source, labelled GRB 260110A, starting at 2026-01-10T03:28:54.35 UTC (T0), through an offline search with the event-by-event data downloaded through the X-band ground station. The burst was detected within several energy ranges and timescales. The best detection is obtained by the onground Image Trigger (IMT) with a signal-to-noise ratio of 7.1 within 4-20 keV over a time window of 20.48 seconds starting at T0-20.48s. The event is also seen by the onboard trigger but below the alert threshold. The lightcurve shows a single peaked structure lasting around 20 s. The localization of the source is RA, Dec = 333.649, 34.236 degrees: RA (J2000) = 22h14m35.76s Dec (J2000) = 34d14m09.60s with a 90% C.L. radius of 12.4 arcmin (including systematic error of 6 arcmin added in quadrature). We note that no bright catalogued X-ray sources are found in the error box. The time-averaged spectrum from T0-18.5 s to T0+1.5 s in the energy range 5-50 keV is best fitted by a power law. The powerlaw index is -1.77 -0.29/+0.33. With this model, the total fluence in 4-120 keV is (2.95 +0.32/-1.63)e-7 erg/cm^2. All quoted errors are at the 68% confidence level. The Space 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. ECLAIRs was developed jointly by APC, CEA, CNES, and IRAP. The SVOM point of contact for this event is : Marius Brunet : marius.brunet at irap.omp.eu Please contact him by email if you require additional information regarding the SVOM follow-up of this burst. View this GCN Circular online at https://gcn.nasa.gov/circulars/43448. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41542] EP260119a: EP-WXT detection of a fast X-ray transient
by GCN Circulars 19 Jan '26

19 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43447 SUBJECT: EP260119a: EP-WXT detection of a fast X-ray transient DATE: 26/01/19 08:03:26 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. H. Jiang (NJU), D. Zhu, K.J. Zhang ,Y.H. Cheng (SWIFAR,YNU), R. X. Hu (WHU)，H. Sun (NAO, CAS) on behalf of the Einstein Probe (EP) team: We report on the detection of a fast X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP260119a. The source has a signal-to-noise ratio of 7.5. But the total number of counts is insufficient to trigger the WXT on-board trigger unit. The event started at 2026-01-19T00:13:48 (UTC) and lasted for almost 300 seconds. The WXT position of the source is R.A. = 158.082 deg, DEC = 65.505 deg (J2000) with an uncertainty of 2.3 arcmin in radius (90% C.L. statistical and systematic). The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a photon index of 1.8(-/+0.6) and with a fixed galactic hydrogen column density of 1.2 x 10^20 cm^-2. The derived average unabsorbed 0.5-4 keV flux is 4.4 (-1.3/+1.8) x 10^-11 erg/s/cm^2. The peak flux in the 0.5-4 keV band reaches 4.8 x 10^-10 erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. The stellar flare origin can not be fully ruled out. A follow-up observation with EP-FXT has been scheduled. 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/43447. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41541] Swift GRB260118.48: Global MASTER-Net observations report
by GCN Circulars 18 Jan '26

18 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43446 SUBJECT: Swift GRB260118.48: Global MASTER-Net observations report DATE: 26/01/18 20:38:22 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-SAAO robotic telescope [1] located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB260118.48 (trigger No 1442056,11h 20m 55.22s , -61d 54m 33.5s, R=0.05) errorbox 32275 sec after notice time and 32359 sec after trigger time at 2026-01-18 20:27:14 UT, with upper limit up to 18.2 mag. The observations began at zenith distance = 59 deg. The sun altitude is -27.5 deg. The galactic latitude b = -1 deg., longitude l = 293 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3106346 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 32450 | MASTER-SAAO | C | 180 | 18.0 | 32450 | MASTER-SAAO | C | 180 | 18.3 | 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/43446. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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