- 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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