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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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