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

[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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[vsnet-grb-info 41540] GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
by GCN Circulars 18 Jan '26

18 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43445 SUBJECT: GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations DATE: 26/01/18 19:35:14 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Francis Fortin (IRAP), William H. Lee (UNAM), Benjamin Schneider (LAM), Noémie Globus (UNAM), Stéphane Basa (UAR Pytheas), Alan M. Watson (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), 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), Antonio de Ugarte Postigo (LAM), J. T. Palmerio (CEA/Irfu) report: We imaged the field of the SVOM GRB 260117A (Palmerio et al., GCN Circ. 43437) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2026-01-18 07:56 to 13:25 UTC (from 12.22 to 17.70 hours after the trigger) and obtained 240 minutes 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. At the position of the source detected with Swift/XRT (Salvaggio et al., GCN 43439; Evans et al., GCN 43438) and SVOM/VT (Li et al., GCN Circ. 43441), we detect a source with preliminary magnitudes of r = 24.27 +/- 0.12, z > 23.7 (3 sigma). It is not trivial to compare our results with SVOM/VT as our filters are different. Our r filter lies within VT_B and our z filter lies within VT_R. Nevertheless, our z upper limit does suggest that the source seen by Li et al. has faded and therefore is the afterglow. We also note that in deep CFHT images from previous epochs, there is a source at this position with r = 24.41 ± 0.17. The source is also faintly visible in the PS1 r image. Therefore, we suggest that this source might be the host galaxy. 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/43445. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41539] SVOM GRB260117.82: Global MASTER-Net observations report
by GCN Circulars 18 Jan '26

18 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43444 SUBJECT: SVOM GRB260117.82: Global MASTER-Net observations report DATE: 26/01/18 16:56:24 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 SVOM GRB260117.82 (trigger No 1768678985,12h 32m 45.48s , +43d 53m 33.7s, R=0.1628) errorbox 70494 sec after notice time and 72263 sec after trigger time at 2026-01-18 15:47:28 UT, with upper limit up to 19.6 mag. The observations began at zenith distance = 58 deg. The sun altitude is -54.8 deg. The galactic latitude b = 73 deg., longitude l = 133 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3105573 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 72294 | 2026-01-18 15:47:28 | MASTER-Tunka | (12h 32m 04.93s , +43d 44m 06.4s) | C | 60 | 19.6 | 72294 | 2026-01-18 15:47:29 | MASTER-Tunka | (12h 32m 43.91s , +43d 35m 22.6s) | C | 60 | 19.5 | 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/43444. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41538] Fermi-LAT Gamma-ray Observations of IceCube-260115A
by GCN Circulars 18 Jan '26

18 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43443 SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-260115A DATE: 26/01/18 12:14:23 GMT FROM: Simone Garrappa at Weizmann Institute of Science <simone.garrappa(a)weizmann.ac.il> S. Garrappa (Weizmann Institute of Science), L. Pfeiffer (Univ. of Wuerzburg), S. Buson (DESY, Univ. of Wuerzburg) and C. Bartolini (INFN Bari) on behalf of the Fermi-LAT collaboration: We report an analysis of observations of the vicinity of the high-energy IC260115A neutrino event (GCN 43421) 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 2026-01-15 at 17:32:35.71 UTC (T0) with J2000 position RA = 145.77 (+2.29, -1.77) deg, Decl. = 12.41 (+1.18, -0.91) deg 90% PSF containment (J2000). No cataloged gamma-ray sources are found within the 90% IC260115A 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 IC260115A 90% confidence localization. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC260115A best-fit position, the >100 MeV flux upper limit (95% confidence) is <4.3e-10 ph cm^-2 s^-1 for ~17-years (2008-08-04 / T0), <3.8e-09 (<2.9e-07) 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 source, the Fermi-LAT contact person is S. Garrappa (simone.garrappa at weizmann.ac.il). 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/43443. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41537] Swift trigger on the HMXB 1A 1118-61
by GCN Circulars 18 Jan '26

18 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43442 SUBJECT: Swift trigger on the HMXB 1A 1118-61 DATE: 26/01/18 11:57:09 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> R. Gupta (NASA GSFC), N. P. M. Kuin (UCL-MSSL), K. L. Page (U Leicester) and T. Sakamoto (AGU) report on behalf of the Neil Gehrels Swift Observatory Team: At 11:27:54 UT, the Swift Burst Alert Telescope (BAT) triggered and located the HMXB 1A 1118-61 (trigger 1442056). Swift slewed immediately to the source. The BAT on-board calculated location is RA, Dec 170.230, -61.909 which is RA(J2000) = 11h 20m 55s Dec(J2000) = -61d 54' 32" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual for an image trigger, the light-curve does not show significant structure. The XRT began observing the field at 11:29:57.7 UT, 122.8 seconds after the BAT trigger. XRT found a bright X-ray source located at RA, Dec 170.2386, -61.9161 which is equivalent to: RA(J2000) = 11h 20m 57.26s Dec(J2000) = -61d 54' 58.0" with an uncertainty of 5.1 arcseconds (radius, 90% containment). This location is 29 arcseconds from the BAT onboard position, within the BAT error circle. This position is 1.8 arcseconds from a known X-ray source: 1A 1118-61. This source is in the Swift XRT LSXPS catalogue with a mean 0.3-10 keV count-rate of 0.2537 +/- 0.0012 ct/sec; see https://www.swift.ac.uk/LSXPS/LSXPS%20J112057.1-615459 for details of these previous observations. No event data are yet available to determine the column density using X-ray spectroscopy. UVOT took a finding chart exposure of 250 seconds with the U filter starting 188 seconds after the BAT trigger. The source is clearly detected at a U magnitude of 12.7. No correction has been made for the large, but uncertain, extinction expected. This is the second recent trigger by Swift-BAT on this source, following yesterday's event reported in GCN Circ. 43435, showing that the source is increasing in brightness. View this GCN Circular online at https://gcn.nasa.gov/circulars/43442. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41536] GRB 260117A: SVOM/VT optical candidate
by GCN Circulars 18 Jan '26

18 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43441 SUBJECT: GRB 260117A: SVOM/VT optical candidate DATE: 26/01/18 08:09:33 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, C. Wu, Y. N. Ma, Y. L. Qiu, Z. H. Yao, L.P. Xin, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. R. Xu, J. S. Deng, J. Y. Wei (NAOC), J. T. Palmerio, D. Adrien(CEA/Irfu) report on behalf of the SVOM/VT team. SVOM/VT performed ToO observation for the long faint burst GRB 260117A triggered by SVOM/ECLAIRs (sb26011705, Palmerio et al., GCN 43437). The observation started at 2026-01-17T22:14:53 UTC, i.e., 2.398 hours post trigger in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. An uncatalogued source was detected only in VT_R stacked images within the error box of EP/FXT and source 1 from Swift-XRT (Salvaggio et al., GCN 43439; Evans et al., GCN 43438), compared to the Legacy survey catalog. It is also located in the error box of ECLAIRs (Palmerio et al., GCN 43437). The position is at R.A., Dec. = 188.138564, 43.912747 degrees, equivalent to: R.A. (J2000) = 12:32:33.25 Dec. (J2000) = +43:54:45.89 with an uncertainty of 0.5 arcsec. The measurements in AB magnitudes are given below: Mid_time Band Exposure Time Magnitude (AB) 4.36 hour VT_R 68*70 sec 22.98+/-0.25 4.36 hour VT_B 73*70 sec >23.8 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/43441. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41535] GRB 260117A: SVOM/C-GFT upper limit
by GCN Circulars 18 Jan '26

18 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43440 SUBJECT: GRB 260117A: SVOM/C-GFT upper limit DATE: 26/01/18 05:54:34 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), J. T. Palmerio, D. Adrien(CEA/Irfu) report on behalf of the SVOM/C-GFT team: We observed the field of GRB 260117A (SVOM trigger: sb26011705) detected by SVOM/ECLAIRs (Palmerio et al., GCN 43437) with LATIOS on SVOM/C-GFT. Observations started at 2026-01-17T19:44:47 UTC, ~82 seconds after the trigger. We obtained g, r, and i-band follow-up imaging. After preliminary analysis，no credible candidate was detected within the error box provided by EP/FXT and Swift/XRT (Evans et al., GCN 43438; Salvaggio et al., GCN 43439) in our images. The 3-upper limits in the early phase are: | Mid_t - T0 (min) | Exposure Time (s) | Band | Upper Limit (AB) | |-----------------|-------------------|------|------------------| | 4.6 | 5×10 | i | 18.5 | | 14.1 | 10×30 | g | 19.7 | The photometry was calibrated against UCAC4 catalogue and no correction for Galactic dust extinction was applied. We thank the observation assistants Bo-Wen Li and Hong-Xv Xue 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/43440. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41534] GRB 260117A: Swift-XRT observations
by GCN Circulars 18 Jan '26

18 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43439 SUBJECT: GRB 260117A: Swift-XRT observations DATE: 26/01/18 04:47:03 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 performed follow-up observations of the SVOM/ECLAIRs-detected burst GRB 260117A, collecting 2.9 ks of Photon Counting (PC) mode data between T0+12.5 ks and T0+19.8 ks. Two uncatalogued X-ray sources have been detected, however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below: Source 1: RA (J2000.0): 188.1380 = 12h 32m 33.12s Dec (J2000.0): +43.9131 = +43d 54' 47.3" Error: 5.3 arcsec (radius, 90% conf.) Count-rate: (8.6 +/- 2.1)e-3 ct s^-1 Distance: 152 arcsec from SVOM/ECLAIRs position. Flux: (3.90 +/- 0.93)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 2: RA (J2000.0): 188.3043 = 12h 33m 13.03s Dec (J2000.0): +43.8449 = +43d 50' 41.7" Error: 5.8 arcsec (radius, 90% conf.) Count-rate: (4.0 [+1.7, -1.4])e-3 ct s^-1 Distance: 343 arcsec from SVOM/ECLAIRs position. Flux: (1.29 [+0.56, -0.44])e-10 erg cm^-2 s^-1 (observed, 0.3-10 keV) 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/00021898. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43439. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41533] GRB 260117A: Swift ToO observations
by GCN Circulars 17 Jan '26

17 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43438 SUBJECT: GRB 260117A: Swift ToO observations DATE: 26/01/17 23:10:27 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 SVOM/ECLAIRs-detected event GRB 260117A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021898 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 SVOM/ECLAIRs 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/43438. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41532] GRB 260117A: SVOM detection of a long faint burst
by GCN Circulars 17 Jan '26

17 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43437 SUBJECT: GRB 260117A: SVOM detection of a long faint burst DATE: 26/01/17 20:12:45 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> J. T. Palmerio, D. Adrien, S. Schanne, D. Turpin (CEA/Irfu), F. Piron (LUPM), report on behalf of the SVOM mission team: At 2026-01-17T19:43:25 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260117A (SVOM burst-id sb26011705). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was only detected by the Count-Rate Trigger (CRT), which produced a sequence of 1 alert. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 8.05 in the [5-20] keV energy band over a time window of 20.48 seconds starting at 2026-01-17T19:43:05. The localization of the best alert is R.A., Dec. 188.1895, 43.8927 degrees: R.A. (J2000) = 12h32m45.49s Dec. (J2000) = 43d53m33.87s with a 90% confidence level (C.L.) radius of 9.77 arcmin (including systematic error of 2 arcmin added in quadrature). This burst was also detected by SVOM/GRM with a significance of 8.90. The SVOM/GRM light curve shows a double peak structure with a T90 duration of about 20 (-4 +5) seconds. Due to the detection significance being below the slew threshold, no immediate slew was performed on this burst. No X-ray observation could be performed by SVOM/MXT for the time being. No optical observation could be performed by SVOM/VT for the time being. 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. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Jesse T. Palmerio: jesse.palmerio(a)cea.fr. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/43437. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41531] EP 260116a: COLIBRÍ optical upper limit
by GCN Circulars 17 Jan '26

17 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43436 SUBJECT: EP 260116a: COLIBRÍ optical upper limit DATE: 26/01/17 10:52:27 GMT FROM: Francesco at Aix-Marseille Université, CPPM/CNRS <francesco.magnani.work(a)gmail.com> Francesco Magnani (CPPM), Leonardo García García (UNAM), Stéphane Basa (UAR Pytheas), Jean-Luc Atteia (IRAP), William H. Lee (UNAM), Alan M. Watson (UNAM), Edilberto Aguilar-Ruiz (UNAM), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Asuka Kuwata (UNAM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We imaged the field of the EP 260116a (C. Wang at al., GCN Circ. 43424) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-01-17 06:05:01 to 07:29:06 UTC (from 29.9 to 31.3 hours after the trigger) and obtained 64 minutes of simultaneous exposure in the r, z filters. The data were reduced and coadded with the COLIBRÍ pipeline 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. In the stacked image, we do not detect any new optical source at the EP/WXT error region (C. Wang et al., GCN Circ. 43424) down to the following 3-sigma limit: r > 23.52 z > 22.44 This upper limit is consistent with the one reported by Junjie-Jin et al. (GCN Circ. 43425), V. Lipunov et al. (GCN Circ. 43427), A. Gupta et al. (GCN Circ. 43430), and A. Bochenek et al. (GCN Circ. 43432). 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/43436. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41530] Swift triggered on the HMXB 1A 1118-61
by GCN Circulars 17 Jan '26

17 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43435 SUBJECT: Swift triggered on the HMXB 1A 1118-61 DATE: 26/01/17 06:59:18 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> R. Gupta (NASA GSFC) and K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift Observatory Team: At 06:28:58 UT, the Swift Burst Alert Telescope (BAT) triggered and located the HMXB 1A 1118-61 (trigger 1441823). Swift slewed soon after the event. The BAT on-board calculated location is RA, Dec 170.183, -61.905 which is RA(J2000) = 11h 20m 44s Dec(J2000) = -61d 54' 17" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure. This is an image-triggered event. The XRT began observing the field at 06:35:17.6 UT, 378.7 seconds after the BAT trigger. XRT found a bright X-ray source located at RA, Dec 170.2403, -61.9170 which is equivalent to: RA(J2000) = 11h 20m 57.67s Dec(J2000) = -61d 55' 01.2" with an uncertainty of 5.5 arcseconds (radius, 90% containment). This location is 106 arcseconds from the BAT onboard position, within the BAT error circle. This position is 4.3 arcseconds from a known X-ray source: LSXPS J112057.1-615459. This source is in the Swift XRT LSXPS catalogue with a mean 0.3-10 keV count-rate of 0.2537 +/- 0.0012 ct/sec; see https://www.swift.ac.uk/LSXPS/LSXPS%20J112057.1-615459 for details of these previous observations. No event data are yet available to determine the column density using X-ray spectroscopy. This trigger occurred just as Swift was exiting the SAA, so it is not clear at this time whether the source has actually brightened, or if the trigger was caused by the enhanced particle background. View this GCN Circular online at https://gcn.nasa.gov/circulars/43435. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41529] GRB 260115A: GECAM-B observation
by GCN Circulars 17 Jan '26

17 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43434 SUBJECT: GRB 260115A: GECAM-B observation DATE: 26/01/17 00:47:57 GMT FROM: zhangjinpeng(a)ihep.ac.cn Jin-Peng Zhang, Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered in-flight by GRB 260115A, at 2026-01-15T17:46:45.900 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #43417). According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of a bright pulse and some fainter emissions, with a duration (T90) of 4.8 +2.4/-1.4 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb260115A.png The time-averaged spectrum from T0 - 1.0 to T0 + 4.0 s is best fitted by a power law function. The power law index is -2.2 +0.3/-0.4. The event fluence (10-1000 keV) in this time interval is (2.8 +0.7/-0.4)E-06 erg/cm^2. 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/43434. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41528] FRB 20251229A: COLIBRÍ further inspection of the updated localization
by GCN Circulars 17 Jan '26

17 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43433 SUBJECT: FRB 20251229A: COLIBRÍ further inspection of the updated localization DATE: 26/01/17 00:23:03 GMT FROM: Rosa L. Becerra at Instituto de Astronomía, UNAM <rbecerra(a)astro.unam.mx> Rosa L. Becerra (UNAM), Noémie Globus (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Jean-Luc Atteia (IRAP), Edilberto Aguilar-Ruiz (UNAM), Dalya Akl (NYUAD), Camila Angulo (UNAM), 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 reinspected our previous observations of the field of FRB 20251229A (Mulyk et al., GCN Circ. 43334) reported by Globus et al. (GCN Circ. 43431), focusing on the updated baseband localization provided by the CHIME/FRB Collaboration (Mason et al., GCN Circ. 43431). We analysed the data and performed image subtraction using STDWeb/STDPipe (Karpov 2025), with templates from the Pan-STARRS DR2 catalog (Flewelling et al. 2020). In this further inspection, we do not detect any new source or evidence for brightness variability of any object within the localization uncertainty region (Mason et al., GCN Circ. 43431), down to the following 5-sigma limits: r > 22.5, z > 21.5. 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/43433. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41527] EP260116a: Liverpool Telescope upper limits
by GCN Circulars 16 Jan '26

16 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43432 SUBJECT: EP260116a: Liverpool Telescope upper limits DATE: 26/01/16 23:35:52 GMT FROM: A. Bochenek at Liverpool John Moores University <a.m.bochenek(a)2023.ljmu.ac.uk> A. Bochenek and D. A. Perley (LJMU) report: We observed the field of the fast X-ray transient EP260116a (Wang et al., GCN 43424) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 5x100s exposures in the SDSS r and i filters starting at 2026-01-16 21:52:40 UT, approximately 21.7 hours post trigger. Two exposures taken in i-band had to be discarded due to poor seeing. We performed image subtraction of the stacked images of remaining exposures in each filter against Pan-STARRS using PSF matching with the help of PSFEx. We do not detect any new objects within the EP/WXT error region of the transient (Wang et al., GCN 43424). The 3-sigma limiting magnitude on the stacked images is r > 22.5 mag and i > 21.9 mag. View this GCN Circular online at https://gcn.nasa.gov/circulars/43432. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41526] FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
by GCN Circulars 16 Jan '26

16 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43431 SUBJECT: FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A DATE: 26/01/16 21:59:12 GMT FROM: masonng(a)mit.edu Mason Ng (McGill University, Trottier Space Institute) on behalf of the CHIME/FRB Collaboration: In GCN 43334 (ATel 17574), we reported the discovery of the potentially hyperactive repeating fast radio burst source, FRB 20251229A. In that ATel, we published best-fit localization coordinates from an initial analysis of the raw voltage (baseband) data using an older version of the localization pipeline (Michilli et al. 2021). Here, we update the best-fit baseband localization for FRB 20251229A using a newer version of the pipeline, with the latest calibration methods. The new localization, which is approximately 35" away from the previously reported localization (GCN 43334, ATel 17574), is the following with errors quoted at 1-sigma uncertainty: RA (J2000): 20h 41m 23.9s +/- 1.8s, Dec. (J2000): 16d 01' 31" +/- 36" RA (J2000): 310.3494 +/- 0.0077 deg., Dec. (J2000): 16.0252 +/- 0.0099 deg. View this GCN Circular online at https://gcn.nasa.gov/circulars/43431. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41525] EP260116A: 1.3m DFOT optical upper limit
by GCN Circulars 16 Jan '26

16 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43430 SUBJECT: EP260116A: 1.3m DFOT optical upper limit DATE: 26/01/16 21:53:31 GMT FROM: ANSHIKA GUPTA at ARIES <anshika05180(a)gmail.com> Anshika Gupta, Kuntal Misra, Tarak Chand, Debalina Kar, Dhruv Jain, and Pankaj Pawar (ARIES) report: We observed the field of EP260116A detected by EP/WXT (EP Team, GCN 43424) with the 1.3m Devasthal Fast Optical Telescope (DFOT), located at the Devasthal Observatory of the Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations began on 2026-01-16 at 19:01:13 UT, i.e., ~18.87 hours after the EP trigger. We have taken multiple frames with an exposure time of 300s in the R filter. We stacked the images after the alignment. No uncatalogued source is detected in our stacked image within the EP/WXT error box (EP Team, GCN 43424). We obtain the following 3-sigma upper limit in the stacked image: Date Start_UT T_start-T0 (hour) Filter Exp time (s) Magnitude =============================================================== 2026-01-16 19:01:13 ~18.87 R 300s*12 >23.0 The non-detection of the burst is consistent with Junjie-Jin et al. 2026 (GCN 43425); Lipunov et al. 2026 (GCN 43427). The magnitude is not corrected for the Galactic extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalogue. View this GCN Circular online at https://gcn.nasa.gov/circulars/43430. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41524] GRB 260114A: VLT/MUSE spectroscopic observations
by GCN Circulars 16 Jan '26

16 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43429 SUBJECT: GRB 260114A: VLT/MUSE spectroscopic observations DATE: 26/01/16 21:38:14 GMT FROM: Andrea Saccardi at CEA/Irfu <andrea.saccardi(a)cea.fr> A. Saccardi (CEA/Irfu), D. B. Malesani (DAWN/NBI and Radboud), B. Schneider (LAM), G. Corcoran (UCD), H. Fausey (Baylor), L. Izzo (INAF/OACn & DARK/NBI), A. J. Levan (Radboud and Warwick), A. Martin-Carrillo (UCD), G. Tagliaferri (INAF/OAB), N. R. Tanvir (Leicester) report on behalf of the Stargate collaboration: We observed the field of the short GRB 260114A (Eyles-Ferris et al., GCN 43396; Bissaldi, GCN 43400; Ren et al., GCN 43402; Wang et al., GCN 43404; Ridnaia et al., GCN 43413) using the ESO/VLT UT4 (Yepun) equipped with the MUSE integral-field spectrograph, covering 1'x1' centered around the XRT position. The observation mid time was 2026 Jan 15.155 UT (16.05 hr after the Swift/BAT trigger). In proximity of the X-ray localization (Beardmore et al., GCN 43412), several objects are visible in archival images of the field, for some of which we report redshifts. These measurements are based on identification of emission lines due to, among others, [O III], Hbeta, and the [O II] doublet. The redshift of the first object in the list has been already reported by Yang et al. (GCN 43410). Three of the objects have redshift close to z = 0.52, reinforcing that this is the likely GRB redshift. We note the presence of a star in chance alignment with the galaxy at z = 0.524. Its spectrum easily identifies it as an early M star, and its PSF is unresolved down to ~0.5" seeing in our HAWK-I image (Schneider et al., GCN 43423). | RA (J2000) | Dec (J2000) | Redshift | Comments | | ----------- | ----------- | -------- | --------- | | 04:58:23.43 | -08:00:50.5 | 0.524 | GCN 43410 | | 04:58:23.57 | -08:00:52.2 | 0.514 | | | 04:58:23.60 | -08:01:00.4 | 0.523 | | | 04:58:22.72 | -08:00:47.7 | 0.288 | | | 04:58:23.41 | -08:00:49.7 | 0 | M star | A finding chart showing the positions of the above objects is posted at the following link (the XRT position is taken from https://www.swift.ac.uk/xrt_positions/) https://sid.erda.dk/share_redirect/Ba6h5nsfin We thank Phil Evans (Leicester) for insightful clarifications about the XRT localization. We also acknowledge excellent support from the observing staff at Paranal, in particular Thomas Rivinius, Julien Drevon, Camila de Sa Freitas, Rodrigo Romero. View this GCN Circular online at https://gcn.nasa.gov/circulars/43429. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41523] IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 16 Jan '26

16 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43428 SUBJECT: IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube DATE: 26/01/16 21:03:16 GMT FROM: Yuhua Yao at IceCube/UW-Madison <yyao255(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-260115A (https://gcn.nasa.gov/circulars/43421) in a time range of 1000 seconds centered on the alert event time (2026-01-15 17:24:15.710 UTC to 2026-01-15 17:40:55.710 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-260115A. We report a p-value of 1.00 in this time window. IceCube’s sensitivity to neutrino point sources with an E^-2.5 spectrum, expressed as E^2 dN/dE evaluated at 1 TeV, is 1.3e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-260115A in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 2e+02 GeV and 1e+05 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2026-01-14 17:32:35.710 UTC to 2026-01-16 17:32:35.710 UTC). In this case, we report a p-value of 0.19, consistent with no significant excess of track events. IceCube’s sensitivity to neutrino point sources with an E^-2.5 spectrum, expressed as E^2 dN/dE evaluated at 1 TeV, ranges from 1.5e-01 to 1.6e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-260115A in a 2 day time window. 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. [1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021) View this GCN Circular online at https://gcn.nasa.gov/circulars/43428. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41522] EP260116a: Global MASTER-Net observations report
by GCN Circulars 16 Jan '26

16 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43427 SUBJECT: EP260116a: Global MASTER-Net observations report DATE: 26/01/16 17:09:27 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 EP260116a ( EP Team et al., GCN 43424) errorbox 16387 sec after notice time and 59243 sec after trigger time at 2026-01-16 16:36:14 UT, with upper limit up to 19.6 mag. The observations began at zenith distance = 44 deg. The sun altitude is -58.9 deg. The galactic latitude b = 13 deg., longitude l = 213 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3104022 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 59273 | 2026-01-16 16:36:14 | MASTER-Tunka | (07h 33m 54.24s , +06d 54m 24.5s) | C | 60 | 18.3 | 59273 | 2026-01-16 16:36:14 | MASTER-Tunka | (07h 34m 21.60s , +06d 48m 07.1s) | C | 60 | 18.8 | 59333 | 2026-01-16 16:36:14 | MASTER-Tunka | (07h 34m 21.60s , +06d 48m 07.2s) | C | 180 | 19.5 | Coadd 59351 | 2026-01-16 16:37:32 | MASTER-Tunka | (07h 34m 00.18s , +06d 53m 22.7s) | C | 60 | 18.3 | 59351 | 2026-01-16 16:37:32 | MASTER-Tunka | (07h 34m 27.46s , +06d 47m 05.3s) | C | 60 | 18.8 | 59425 | 2026-01-16 16:38:45 | MASTER-Tunka | (07h 33m 55.76s , +06d 52m 20.0s) | C | 60 | 18.5 | 59425 | 2026-01-16 16:38:45 | MASTER-Tunka | (07h 34m 23.07s , +06d 46m 03.1s) | C | 60 | 18.8 | 59499 | 2026-01-16 16:39:59 | MASTER-Tunka | (07h 34m 01.62s , +06d 52m 23.8s) | C | 60 | 18.5 | 59499 | 2026-01-16 16:39:59 | MASTER-Tunka | (07h 34m 28.91s , +06d 46m 06.5s) | C | 60 | 19.0 | 59559 | 2026-01-16 16:39:59 | MASTER-Tunka | (07h 34m 28.91s , +06d 46m 06.5s) | C | 180 | 19.6 | Coadd 59572 | 2026-01-16 16:41:13 | MASTER-Tunka | (07h 33m 57.80s , +06d 54m 14.6s) | C | 60 | 18.5 | 59572 | 2026-01-16 16:41:13 | MASTER-Tunka | (07h 34m 25.14s , +06d 47m 57.4s) | C | 60 | 19.0 | 59647 | 2026-01-16 16:42:27 | MASTER-Tunka | (07h 33m 57.89s , +06d 52m 28.8s) | C | 60 | 18.5 | 59647 | 2026-01-16 16:42:27 | MASTER-Tunka | (07h 34m 25.22s , +06d 46m 11.7s) | C | 60 | 19.0 | 59721 | 2026-01-16 16:43:41 | MASTER-Tunka | (07h 34m 01.50s , +06d 53m 59.9s) | C | 60 | 18.6 | 59721 | 2026-01-16 16:43:41 | MASTER-Tunka | (07h 34m 28.85s , +06d 47m 42.9s) | C | 60 | 19.0 | 59795 | 2026-01-16 16:44:56 | MASTER-Tunka | (07h 33m 55.46s , +06d 53m 09.1s) | C | 60 | 18.4 | 59795 | 2026-01-16 16:44:56 | MASTER-Tunka | (07h 34m 22.81s , +06d 46m 52.3s) | 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/43427. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41521] GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
by GCN Circulars 16 Jan '26

16 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43426 SUBJECT: GRB 260111A: COLIBRÍ fading of the optical counterpart candidate DATE: 26/01/16 17:02:10 GMT FROM: Benjamin Schneider at MIT <bschn(a)mit.edu> Benjamin Schneider (LAM), Enrique Moreno Méndez (UNAM), 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), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), and Antonio de Ugarte Postigo (LAM): We imaged the field of the Fermi/Swift GRB 260111A (Fermi GBM Team, GCN 43370, GCN 43384; Ronchini et al., GCN 43377, Luo et al., GCN 43385, Pfeiffer et al., GCN 43397) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-01-16 10:52 to 13:22 UTC (from 4.77 to 4.87 days after the trigger) and obtained 89 and 75 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 is not corrected for Galactic extinction. The optical afterglow candidate reported by Ducoin et al., GCN 43386, consistent with the XRT #2 source (Lanava et al., GCN 43388), is no longer detected in the images down to the following 3-sigma limit: r > 24.4 z > 23.0 Our measurements indicate fading, and we propose this source as the optical afterglow of GRB 260111A. 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/43426. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41520] EP260116a: Xinglong optical upper limit
by GCN Circulars 16 Jan '26

16 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43425 SUBJECT: EP260116a: Xinglong optical upper limit DATE: 26/01/16 16:49:09 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 EP260116a by EP-WXT (GCN Circular 43424), we observed the field of EP260116a using the 2.16-m telescope at Xinglong Observatory, NAOC. We obtained 3x300s clear-band frames with a median time of 2026-01-16T15:26:52 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 43424), down to 5-sigma limiting magnitudes of N ~ 20.8, calibrated with Pan-STARRS sources in the field. Also there is no apparent brightening for the catalogued sources within the error circle. View this GCN Circular online at https://gcn.nasa.gov/circulars/43425. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41519] EP260116a: Einstein Probe detection of an X-ray transient
by GCN Circulars 16 Jan '26

16 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43424 SUBJECT: EP260116a: Einstein Probe detection of an X-ray transient DATE: 26/01/16 12:01:43 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> C. Wang, Z. X. Li, G. L. Huang, J. Y. Cao (IHEP), Y. H. Jiang (NJU), Z. X. Ling (NAOC) on behalf of the Einstein Probe (EP) team: We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP260116a. A significant outburst is observed in the WXT light curve. The transient triggered EP-WXT (ID: 01709251336) at 2026-01-16T00:08:51 (UTC). The WXT position of the source is R.A. = 113.768 deg, DEC = 6.329 deg (J2000) with an uncertainty of 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 hydrogen column density of 7.65 x 10^20 cm^-2 and a photon index of 1.77. The derived average unabsorbed 0.5-4 keV flux is 7.16 x 10^-11 erg/s/cm^2. A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically with a 24-minute delay, starting at 2026-01-16 00:32:38 (UTC), by which time the outburst had already ended. Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 113.7617 deg, DEC = 6.3244 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). The average FXT 0.5 - 10.0 keV spectra can also be fitted with an absorbed power law with the same hydrogen column density and a photon index of 1.98. The derived average unabsorbed 0.5-10.0 keV flux is 9.52 x 10^-14 erg/s/cm^2. 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/43424. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41518] GRB 260114A: VLT/HAWK-I near-infrared upper limits
by GCN Circulars 16 Jan '26

16 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43423 SUBJECT: GRB 260114A: VLT/HAWK-I near-infrared upper limits DATE: 26/01/16 11:26:08 GMT FROM: Benjamin Schneider at MIT <bschn(a)mit.edu> B. Schneider (LAM), D. B. Malesani (DAWN/NBI and Radboud), G. Corcoran (UCD), M. De Pasquale (Univ. Messina), H. Fausey (Baylor), B. P. Gompertz (Birmingham), A. J. Levan (Radboud and Warwick), R. Z. Li (Yunnan), A. Martin-Carrillo (UCD), G. Pugliese (API), A. Rossi (INAF-OAS), N. R. Tanvir (Leicester), A. L. Thakur (INAF-IAPS), S. D. Vergani (LUX-Paris Obs.) report on behalf of the Stargate collaboration: We observed the field of the short GRB 260114A (Eyles-Ferris et al., GCN 43396; Bissaldi, GCN 43400; Ren et al., GCN 43402; Wang et al., GCN 43404; Ridnaia et al., GCN 43413) using the ESO/VLT UT4 equipped with the HAWK-I instrument. Observations were carried out over two nights, with mean epochs Jan 15.06 and 16.05UT (13.8 and 37.6 hr after the trigger, respectively), both in the H band, with an exposure time of 30 min each. No new sources are detected consistent with the Swift/XRT position, except for two (possibly three) objects (Li et al., GCN 43398) visible in the Legacy survey, one of which is a galaxy at z = 0.524 (Yang et al., GCN 43410). Image subtraction between the two epochs was carried out with HOTPANTS (Becker et al. 2015). No source is detected in the difference image down to a limiting magnitude H > 24.2 (AB, 3-sigma). Our non-detection is consistent with the limits provided by Brivio et al. (GCN 43407) and Yang et al. (GCN 43414). We acknowledge excellent support from the observing staff at Paranal, in particular Thomas Rivinius, Julien Drevon, Camila de Sa Freitas, Rodrigo Romero. View this GCN Circular online at https://gcn.nasa.gov/circulars/43423. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41517] IceCube Alert 260115.73: Global MASTER-Net observations report
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43422 SUBJECT: IceCube Alert 260115.73: Global MASTER-Net observations report DATE: 26/01/15 20:13:29 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 IceCube Alert 260115.73 (trigger No 80302474,09h 45m 33.60s , +12d 16m 40.8s, R=1.18) errorbox 9252 sec after notice time and 9296 sec after trigger time at 2026-01-15 20:07:31 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 79 deg. The sun altitude is -24.5 deg. The galactic latitude b = 45 deg., longitude l = 223 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3103091 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 9326 | 2026-01-15 20:07:31 | MASTER-SAAO | (09h 40m 55.07s , +12d 14m 34.0s) | C | 60 | 14.4 | 9326 | 2026-01-15 20:07:31 | MASTER-SAAO | (09h 39m 05.66s , +12d 30m 27.4s) | C | 60 | 17.9 | 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/43422. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41516] IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43421 SUBJECT: IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 26/01/15 20:05:03 GMT FROM: A. Zegarelli at Ruhr University Bochum <azegarelli(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 26-01-15 at 17:32:35.71 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 2.0497 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/141917_80302474.amon) more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 26-01-15 Time: 17:32:35.71 UT RA: 145.77 (+2.29/-1.77 deg 90% PSF containment) J2000 Dec: 12.41 (+1.18/-0.91 deg 90% PSF containment) J2000 As announced in GCN Circular 43419 (https://gcn.nasa.gov/circulars/43419) the probability distribution of the true neutrino direction, allowing the extraction of precise 90% containment regions around the best-fit direction, is now available. The corresponding link (for this alert https://roc-2.icecube.wisc.edu/public/alerts/IceCube-260115A_skymap_probden…) is provided through the GCN schema distributed via Kafka. IceCube GCN notices for high-energy track alerts (Gold and Bronze) are now also distributed via Kafka and can be accessed through the Kafka topic 'gcn.notices.icecube.gold_bronze_track_alerts'. Further details will be available soon at https://gcn.nasa.gov/missions/icecube. Please note that the classical GCN stream will be deactivated in the near future. 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/43421. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41515] GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43420 SUBJECT: GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741) DATE: 26/01/15 19:22:56 GMT FROM: Jochen Greiner at MPE <jcgrog(a)mpe.mpg.de> T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger at 17:46:45 on 15 Jan. 2026 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60). The best-fit position is: RA(2000.0) = 112.0 deg Decl.(2000.0) = 7.9 deg The 1 sigma statistical error radius is 4.6 deg. We estimate an additional systematic error of 1 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB260115741/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB260115741/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB260115741/json View this GCN Circular online at https://gcn.nasa.gov/circulars/43420. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41514] IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43419 SUBJECT: IceCube: GCN Notices for high-energy track alerts now streamed via Kafka DATE: 26/01/15 19:01:43 GMT FROM: A. Zegarelli at Ruhr University Bochum <azegarelli(a)icecube.wisc.edu> The IceCube Collaboration announces that, starting on IceCube-260115A, IceCube’s real-time GCN Notices for high-energy track alerts (Gold and Bronze alerts) are being streamed via the GCN Kafka system, for both preliminary and revised reconstructions. During an initial transition period, IceCube alerts will be distributed simultaneously through both the classic GCN system (via AMON; https://gcn.gsfc.nasa.gov/amon_icecube_gold_bronze_events.html) and GCN over Kafka. This dual-distribution phase is intended to ensure continuity for existing subscribers while enabling the community to migrate to the new Kafka-based infrastructure. After this transition period, alert dissemination will fully switch to GCN Kafka; a further announcement will follow. The transition to GCN Kafka introduces important new features for IceCube alerts: 1. **Release of multi-order probability sky maps** For each revised alert reconstruction (Revision 1), IceCube now provides a multi-order probability map (MOC/HEALPix; https://gcn.nasa.gov/docs/sample/healpix) describing the directional probability distribution of the neutrino event. These maps were not available through the previous alert system and include both statistical and systematic uncertainties, with probability density expressed in units of 1/sr. 2. **Updated calculation of astrophysical probability and false-alarm rate** With GCN Kafka, the reported astrophysical probability (now denoted *p_astro*, previously referred to as *signalness*) and false-alarm rate (FAR) are recalculated using the revised best-fit event direction provided in the updated reconstruction (associated with the second GCN Notice). In the previous system, these quantities were reported using values from the preliminary reconstruction and were not updated after directional refinement. We encourage all users of IceCube real-time alerts to begin subscribing to the Kafka `topic = gcn.notices.icecube.gold_bronze_track_alerts` IceCube Gold/Bronze alerts now follow [this GCN schema structure](https://github.com/nasa-gcn/gcn-schema/blob/v6.1.0/gcn/notices/i…. Detailed documentation describing the alert distribution, schemas, and probability maps will be available soon at: https://gcn.nasa.gov/missions/icecube Questions regarding IceCube alerts may be directed to the IceCube Collaboration. The IceCube real-time alert point of contact can be reached at roc(a)icecube.wisc.edu. View this GCN Circular online at https://gcn.nasa.gov/circulars/43419. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41513] Fermi GRB 260115A: Global MASTER-Net observations report
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43418 SUBJECT: Fermi GRB 260115A: Global MASTER-Net observations report DATE: 26/01/15 18:45:39 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 260115A ( Fermi GBM team, GCN 43417) errorbox 45 sec after notice time and 77 sec after trigger time at 2026-01-15 17:48:03 UT, with upper limit up to 18.5 mag. The observations began at zenith distance = 59 deg. The sun altitude is -41.0 deg. MASTER-Tunka robotic telescope located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB 260115A errorbox 548 sec after notice time and 580 sec after trigger time at 2026-01-15 17:56:26 UT, with upper limit up to 19.5 mag. The observations began at zenith distance = 49 deg. The sun altitude is -59.1 deg. The galactic latitude b = 9 deg., longitude l = 214 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3103145 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 88 | 2026-01-15 17:48:03 | MASTER-Kislovodsk | (07h 36m 40.06s , +03d 42m 42.1s) | C | 20 | 17.2 | 113 | 2026-01-15 17:48:03 | MASTER-Kislovodsk | (07h 36m 40.06s , +03d 42m 42.1s) | C | 70 | 17.9 | Coadd 88 | 2026-01-15 17:48:03 | MASTER-Kislovodsk | (07h 40m 49.00s , +03d 19m 43.0s) | C | 20 | 17.3 | 128 | 2026-01-15 17:48:44 | MASTER-Kislovodsk | (07h 36m 40.13s , +03d 42m 39.9s) | C | 20 | 17.3 | 128 | 2026-01-15 17:48:44 | MASTER-Kislovodsk | (07h 40m 49.04s , +03d 19m 39.7s) | C | 20 | 17.3 | 174 | 2026-01-15 17:49:24 | MASTER-Kislovodsk | (07h 36m 40.22s , +03d 42m 38.6s) | C | 30 | 17.5 | 174 | 2026-01-15 17:49:24 | MASTER-Kislovodsk | (07h 40m 49.10s , +03d 19m 38.3s) | C | 30 | 17.6 | 229 | 2026-01-15 17:50:15 | MASTER-Kislovodsk | (07h 36m 40.26s , +03d 42m 37.7s) | C | 40 | 17.7 | 289 | 2026-01-15 17:50:15 | MASTER-Kislovodsk | (07h 36m 40.26s , +03d 42m 37.7s) | C | 160 | 18.5 | Coadd 295 | 2026-01-15 17:51:15 | MASTER-Kislovodsk | (07h 36m 40.31s , +03d 42m 37.5s) | C | 50 | 17.8 | 295 | 2026-01-15 17:51:15 | MASTER-Kislovodsk | (07h 40m 49.19s , +03d 19m 36.6s) | C | 50 | 18.0 | 385 | 2026-01-15 17:52:36 | MASTER-Kislovodsk | (07h 36m 40.38s , +03d 42m 37.5s) | C | 70 | 18.0 | 391 | 2026-01-15 17:52:42 | MASTER-Kislovodsk | (07h 40m 49.30s , +03d 19m 36.9s) | C | 70 | 18.2 | 611 | 2026-01-15 17:56:26 | MASTER-Tunka | (07h 20m 16.73s , +03d 41m 02.8s) | C | 60 | 19.5 | 611 | 2026-01-15 17:56:26 | MASTER-Tunka | (07h 19m 45.70s , +03d 47m 07.0s) | C | 60 | 19.2 | 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/43418. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41512] GRB 260115A: Fermi GBM Final Real-time Localization
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43417 SUBJECT: GRB 260115A: Fermi GBM Final Real-time Localization DATE: 26/01/15 17:57:28 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 17:46:45 UT on 15 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260115A (trigger 790192010.88085 / 260115741). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 110.2, Dec = 3.3 (J2000 degrees, equivalent to J2000 07h 20m, 3d 17'), with a statistical uncertainty of 5.1 degrees. The angle from the Fermi LAT boresight is 83.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260115741/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260115741/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260115741/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43417. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41511] GRB260114A: STEP/T80S optical limits
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43416 SUBJECT: GRB260114A: STEP/T80S optical limits DATE: 26/01/15 16:20:05 GMT FROM: André Santos at Centro Brasileiro de Pesquisas Físicas (CBPF) <andsouzasanttos(a)gmail.com> A. Santos (CBPF), C. R. Bom (CBPF), C. D. Kilpatrick (Northwestern), L. Santana-Silva (CBPF), P. Darc (CBPF/Northwestern), Gabriel Teixeira (CBPF/UCA), C. Mendes de Oliveira (IAG-USP) report on behalf of the STEP collaboration: We conducted optical follow up with the T80S 0.8-m robotic telescope with the S-PLUS Transient Extension Program (STEP; Santos et al., 2024, MNRAS, 529, 59) of the short gamma-ray burst GRB260114A discovered by the Fermi-GBM, Swift-BAT and XRT instruments (GCN 43395,43396). The T80S observations started on Jan 15 03:18:38 UT (~16 hours after the trigger). We obtained images totaling 1200s (6x200s) in i-band with the T80S camera centered at the position reported in the Swift-BAT and XRT report at R.A.=04:58:23.59 and Decl.=-08:00:51.6 (J2000). After subtracting a Pan-STARRS DR2 template image from the T80S coadded frame using photpipe (Rest et al., 2005, ApJ, 634, 1103), we do not detect any transient source in our difference image within the XRT error circle and derive a 3-sigma limiting magnitude of i > 22.4 mag. View this GCN Circular online at https://gcn.nasa.gov/circulars/43416. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41510] GRB 251222A: radio detection with the VLA
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43415 SUBJECT: GRB 251222A: radio detection with the VLA DATE: 26/01/15 15:16:45 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 03:47:54 UT on 2025 December 24 (T_mid = 1.48 days post-burst) the Karl G. Jansky VLA observed the field of GRB 251222A / EP251222B (Fermi GBM team, GCN 43186, 43222; SVOM team, GCN 43188, GCN 43202; Einstein Probe team, GCN 43201, 43215; Konus-Wind team, GCN 43214; GECAM team, GCN 43218) in three bands, with central frequencies of 6, 10 and 15 GHz. The standard 3C48 was used as bandpass and flux density calibrator, while J0501-0159 was used as phase calibrator. From a preliminary analysis, an unresolved radio source is detected at a position (J2000): RA: 05:08:46.775 +- 0.001 Dec: -07:12:48.80 +- 0.02 consistent with the X-ray (SVOM team, GCN 43188, 43202; Einstein Probe team, GCN 43201, 43215; Swift/XRT team, GCN 43213) and optical (SVOM team, GCN 43189, 43203, 43208; An et al., GCN 43194; Calapai et al., GCN 43195; Durbak et al., GCN 43197; Gupta et al., GCN 43207; GOTO collaboration, GCN 43209; Pérez-Fournon et al., GCN 43212; Gupta et al., GCN 43224; Globus et al., GCN 43225; IKI-GRB-FuN team, GCN 43226, 43230, 43273; GRANDMA collaboration, GCN 43229, 43237; Busmann et al., GCN 43233; Lee et al., GCN 43236; Mephisto Team, GCN 43250) position of the transient. The preliminary analysis yields the following results: ================================================================ T_mid Freq Peak r.m.s. Beam PA [days] [GHz] [uJy/b] [uJy/b] [arcsec^2] [deg] ================================================================ 1.48 6 71 7 1.29x0.91 -22 1.48 10 208 8 0.75x0.58 -16 1.48 15 241 8 0.56x0.38 -28 ================================================================ No source is detected with a >3sigma confidence level at the aforementioned position in the VLASS. However, the r.m.s. noise level of the survey at the GRB location is approximately 150 uJy/b. 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/43415. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41509] GRB 260114A: VLT/HAWK-I near-infrared upper limits
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43414 SUBJECT: GRB 260114A: VLT/HAWK-I near-infrared upper limits DATE: 26/01/15 14:29:46 GMT FROM: Yu-Han Yang at University of Rome Tor Vergata <yyang(a)roma2.infn.it> Yu-Han Yang, Muskan Yadav, Massine El Kabir, Niccolò Passaleva, Eleonora Troja, and Hira Waseem (U Rome) report: We observed the field of GRB 260114A, detected by Swift (Eyles-Ferris et al., GCN 43396), Fermi (Fermi GBM Team, GCN 43395; E. Bissaldi et al. GCN 43400), GECAM-B (Ren et al., GCN 43402) and SVOM/GBM (SVOM/GRM team, GCN 43404) and Konus-Wind (Ridnaia et al., GCN 43413) with the HAWKI imager on the ESO VLT UT4 (Yepun). Observations began 14.2 hours after the trigger and were carried out in the J and Ks filters at an average airmass of 1.0. Within the XRT source position (Beardmore et al., GCN 43412) several catalogued objects are visible in our images, however no obvious counterpart is detected down to a 3-sigma limit Ks>24 AB mag, calibrated using nearby stars in the 2MASS Catalog (Skrutskie et al. 2006). Additional observations to assess variability are planned. We thank the staff at the VLT for the rapid execution of these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/43414. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41508] Konus-Wind detection of GRB 260114A
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43413 SUBJECT: Konus-Wind detection of GRB 260114A DATE: 26/01/15 12:44:01 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 short-duration GRB 260114A (Fermi-GBM detection: Fermi GBM Team, GCN 43395; Bissaldi, GCN 43400; Swift-BAT detection: Eyles-Ferris et al., GCN 43396; GECAM-B observation: Ren et al., GCN 43402; SVOM/GRM observation: Wang et al., GCN 43404) triggered Konus-Wind at T0=42030.729 s UT (11:40:30.729). The burst light curve shows a single pulse which starts at ~T0 s and has a total duration of ~0.3 s. The emission is seen up to ~2 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260114_T42030/ As observed by Konus-Wind, the burst had a fluence of 5.12(-0.25,+0.25)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0+0.024 s, of 2.76(-0.33,+0.33)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+0.256 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = 0.56(-0.15,+0.16) and Ep = 502(-25,+26) keV (chi2 = 36/34 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -3.4 (chi2 = 36/33 dof). Assuming the redshift z=0.524 (Yang et al., GCN 43410) and a standard cosmology model with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the following rest-frame parameters: the isotropic energy release E_iso is 3.86(-0.19,+0.19)x10^51 erg, the peak luminosity L_iso is 3.17(-0.38,+0.38)x10^52 erg/s, and the rest-frame peak energy of the time-integrated spectrum, Ep,i, is 765(-38,+40) keV. With the obtained estimates, the position of GRB 260114A in both Eiso-Ep,z and Liso-Ep,z planes is consistent with short-hard (Type I) GRB population, see http://www.ioffe.ru/LEA/GRBs/GRB260114_T42030/GRB260114A_rest_frame.pdf 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/43413. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41507] GRB 260114A: Swift-XRT refined Analysis
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43412 SUBJECT: GRB 260114A: Swift-XRT refined Analysis DATE: 26/01/15 11:55:38 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> A.P. Beardmore (U. Leicester), B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB), M. Ferro (INAF-OAB), J.A. Kennea (PSU), D.N. Burrows (PSU), S. Lanava (PSU), J.P. Osborne (U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 4.9 ks of XRT data for GRB 260114A, from 107 s to 33.3 ks after the trigger. The data comprise 9 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The best available XRT position (using the promptly downlinked event data, the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue) is RA, Dec = 74.59789, -8.01441 which is equivalent to: RA (J2000): 04h 58m 23.49s Dec(J2000): -08d 00' 51.9" with an uncertainty of 3.2 arcsec (radius, 90% confidence). The light curve can be modelled with a power-law decay with a decay index of alpha=2.9 (NaN, NaN). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.7 (+0.8, -0.6). The best-fitting absorption column is 4.9 (+8.1, -3.9) x 10^21 cm^-2, in excess of the Galactic value of 5.7 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 4.9 x 10^-11 (6.9 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 4.9 (+8.1, -3.9) x 10^21 cm^-2 Galactic foreground: 5.7 x 10^20 cm^-2 Excess significance: 1.9 sigma Photon index: 1.7 (+0.8, -0.6) If the light curve continues to decay with a power-law decay index of 2.9, the count rate at T+24 hours will be 1.2 x 10^-8 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.9 x 10^-19 (8.2 x 10^-19) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/01440319. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43412. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41506] GRB 260114A: 6 GHz VLA observations
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43411 SUBJECT: GRB 260114A: 6 GHz VLA observations DATE: 26/01/15 11:11:29 GMT FROM: Roberto Ricci at INAF-IRA <ricci(a)ira.inaf.it> R. Ricci, M. Yadav, E. Troja (U Rome) report: We observed the short-duration GRB 260114A detected by Fermi-GBM (Fermi team GCN 43395), Swift/BAT (Eyles-Ferris et al. GCN 43396), GECAM-B (Ren et al., GCN 43402) and SVOM/GBM (SVOM/GRM team, GCN 43404) with Very Large Array in C-band at the centre frequency of 6 GHz with a bandwidth of 4 GHz on Jan 15th 2025, 15.5 hours after the burst. After reducing the data using the CASA version v6.6.1 with standard procedures no source was detected inside the Swift/XRT error circle (Eyles-Ferris et al., GCN 43396) down to a 3-sigma flux density upper limit of about 30 microJy/beam. We thank the VLA staff for promptly executing the observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/43411. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41505] GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43410 SUBJECT: GRB 260114A: VLT/X-shooter redshift of the putative host galaxy DATE: 26/01/15 09:07:12 GMT FROM: Yu-Han Yang at University of Rome Tor Vergata <yyang(a)roma2.infn.it> Yu-Han Yang (U Rome), Eleonora Troja (U Rome), and Rosa Becerra (UNAM) report: We observed the field of GRB 260114A, detected by Swift (Eyles-Ferris et al., GCN 43396), Fermi (Fermi GBM Team, GCN 43395; E. Bissaldi et al. GCN 43400), GECAM-B (Ren et al., GCN 43402) and SVOM/GBM (SVOM/GRM team, GCN 43404), with the X-Shooter spectrograph on the ESO VLT UT3 (Melipal). Observations started at 13.8 hours after the GRB trigger, with a total exposure time of 4 × 600 s at an average airmass of ~1.1. In the acquisition image no new uncatalogued source is detected. Several extended sources, also reported in the DESI Legacy Survey, are visible within the XRT error circle. For the brightest object with r~21.1 AB mag we derive a chance alignment of P_cc ~ 4%. Based on a preliminary analysis, we identify multiple emission features corresponding to Hα, Hβ, and the [O II] doublet with a common redshift of z~0.524. We thank the staff at the VLT, especially T. Rivinius and L. Sbordone, for the rapid execution of these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/43410. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41504] GRB 260114A : MITSuME Akeno optical upper limits
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43409 SUBJECT: GRB 260114A : MITSuME Akeno optical upper limits DATE: 26/01/15 06:59:47 GMT FROM: Ichiro Takahashi at Science Tokyo <itakahashi(a)hp.phys.titech.ac.jp> I. Takahashi, M. Sasada, H. Hagio, A. Ochi, Y. Kubo, R. Kato, H. Seki, S. Joshima, Y. Yatsu and N. Kawai (Science Tokyo) report on behalf of the MITSuME collaboration: We observed the field of GRB 260114A detected by Fermi (Fermi GBM team, GCN 43395) and Swift (Eyles-Ferris et al., GCN 43396) with the optical three-color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50-cm telescope Akeno. The observation started at 2026-01-14 11:41:18 UT (52 seconds after the trigger). We stacked the images taken under good conditions. We did not detect any obvious point sources within the Swift/XRT error region (Eyles-Ferris et al., GCN 43396). We obtained the 5-sigma limits of the stacked images as follows: T0+[sec] | MID-UT | T-EXP[sec] | 5-sigma limits ------------------------------------------------------------------------------------------------ 228 | 2026-01-14 11:44:14 | 140 | g'>17.5, Rc>17.5, Ic>17.2 4089 | 2026-01-14 12:48:35 | 4260 | g'>19.8, Rc>19.9, Ic>19.5 ------------------------------------------------------------------------------------------------ T0+ : Elapsed time after the trigger T-EXP: Total exposure time We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 g, r and i bands were converted to our g', Rc and Ic band magnitudes following Tonry et al. (2012), Table 6. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ; https://github.com/MNiwano/Eclaire) View this GCN Circular online at https://gcn.nasa.gov/circulars/43409. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41503] GRB 260114A: COLIBRÍ optical upper limits
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43408 SUBJECT: GRB 260114A: COLIBRÍ optical upper limits DATE: 26/01/15 04:42:41 GMT FROM: Camila Angulo Valdez at UNAM <camiangulo(a)astro.unam.mx> Camila Angulo (UNAM), Jean-Grégoire Ducoin (CPPM), Rosa L. Becerra (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Nathaniel R. Butler (ASU), Damien Dornic (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): We imaged the field of the Swift GRB 260114A (Eyles-Ferris et al., GCN Circ. 43396), also detected by Fermi (Fermi GBM Team, GCN Circ. 43395; E. Bissaldi et al. GCN Circ. 43400), GECAM-B (Ren et al., GCN Circ. 43402), SVOM/GBM (SVOM/GRM team, GCN Circ. 43404), using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-01-15 02:01 to 03:22 UTC (from 14.3 to 15.7 hours after the trigger) and obtained 63 minutes of simultaneous exposure in the r and z filters. The data were reduced and coadded with the COLIBRÍ ASU pipeline and analysed with STDWeb (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. After performing image subtraction of our stacked images against Legacy Survey (Dey et al. 2019) using STDWeb (Karpov 2025), we do not detect any new source at the XRT source position (Eyles-Ferris et al., GCN Circ. 43396) or the optical counterpart previously reported by GMG (Li et al., GCN Circ. 43398) and the Mondy observatory (Volnova et al., GCN Circ. 43401) down to the following 3-sigma limits: r > 24.1, z > 22.7. These upper limits are consistent with later reports from MASTER (Lipunov et al., GCN Circ. 43403), NOT (Corcoran et al., GCN Circ. 43406) and TNG (Brivio et al., GCN Circ. 43407). 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/43408. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41502] GRB 260114A: TNG NIR upper limit
by GCN Circulars 15 Jan '26

15 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43407 SUBJECT: GRB 260114A: TNG NIR upper limit DATE: 26/01/15 01:04:21 GMT FROM: Riccardo Brivio at INAF-OAB <riccardo.brivio(a)inaf.it> R. Brivio, P. D'Avanzo (INAF-OAB), D. B. Malesani (DAWN/NBI & Radboud Univ.), L. Izzo (INAF-OACn), A. Melandri (INAF-OAR), M. Pedani (INAF-TNG) report on behalf of the CIBO collaboration: We observed the field of GRB 260114A detected by Fermi/GBM (Fermi GBM team, GCN 43395), Swift/BAT (Eyles-Ferris et al., GCN 43396), GECAM-B (Ren et al., GCN 43402), and SVOM/GRM (Wang et al., GCN 43404) with the Italian 3.6m TNG telescope, located in the Canary Islands (Spain), equipped with the near-infrared camera NICS in imaging mode. A series of images were obtained with the H filter on 2026-01-14 at a mid-time of about 10.0 hours after the burst. The optical counterpart reported by Li et al. (GCN 43398) and Volnova et al. (GCN 43401) is not detected within the Swift/XRT error circle. We obtain a 3-sigma limiting magnitude of H > 20.6 (Vega; calibrated against the 2MASS catalogue). View this GCN Circular online at https://gcn.nasa.gov/circulars/43407. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41501] GRB 260114A: NOT optical observations
by GCN Circulars 14 Jan '26

14 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43406 SUBJECT: GRB 260114A: NOT optical observations DATE: 26/01/14 21:40:44 GMT FROM: Gregory Corcoran at University College Dublin <gregory.corcoran(a)ucdconnect.ie> G. Corcoran (UCD), A. Martin-Carrillo (UCD), A. Saccardi (CEA/Irfu), D. B. Malesani (DAWN/NBI and Radboud), K. Valeckas (NOT & NBI) report on behalf of a larger collaboration: We observed the field of GRB 260114A detected by Fermi/GBM (Fermi GBM team, GCN 43395), Swift/BAT (Eyles-Ferris et al., GCN 43396), GECAM-B (Ren et al., GCN 43402), and SVOM/GRM (Wang et al., GCN 43404) with the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Our observations consisted of 8 x 300 s exposures in SDSS-r and 5 x 200 s in SDSS-z, starting on Jan 14 2026 at 19:32:39 UT (7.87 hr after the trigger). After performing image subtraction against Legacy Survey using PyZOGY on the stacked images, we do not detect the optical counterpart reported by Li et al. (GCN 43398) and Volnova et al. (GCN 43401) within the Swift/XRT uncertainty region. We obtain the following 3 sigma upper limits in AB magnitudes: r > 24.0 (mid-time of 8.66 hr after the trigger) z > 22.2 (mid-time of 8.30 hr after the trigger) calibrated against nearby stars from the Pan-STARRS catalog, and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43406. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41500] Konus-Wind detection of GRB 251230A / EP251230a
by GCN Circulars 14 Jan '26

14 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43405 SUBJECT: Konus-Wind detection of GRB 251230A / EP251230a DATE: 26/01/14 19:13:21 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 251230A / EP251230a (Swift-BAT detection: Lanava et al., GCN 43252; Einstein Probe-WXT detection: Wang et al., GCN 43259; Wang et al., GCN 43272; Insight-HXMT/HE detection: Guo et al., GCN 43299; GECAM-B detection: Guo et al., GCN 43301) triggered Konus-Wind at T0=04927.542 s UT (01:22:07.542). The burst light curve shows a multipeaked structure which starts at ~T0-25 s and has a total duration of ~73 s. The emission is seen up to ~2 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB251230_T04927/ As observed by Konus-Wind, the burst had the total fluence of 2.03(-0.15,+0.17)x10^-5 erg/cm2, and the 64-ms peak flux, measured from T0-0.224 s, of 2.51(-0.71,+0.80)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+49.408 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.04(-0.14,+0.16) and Ep = 354(-47,+64) keV (chi2 = 93/98 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.2 (chi2 = 93/97 dof). The spectrum near the maximum count rate (measured from T0 to T0+0.256 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.70(-0.51,+0.72) and Ep = 350(-85,+147) keV (chi2 = 19/15 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.8 (chi2 = 18/14 dof). All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/43405. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41499] GRB 260114A: SVOM/GRM observation of a short burst
by GCN Circulars 14 Jan '26

14 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43404 SUBJECT: GRB 260114A: SVOM/GRM observation of a short burst DATE: 26/01/14 17:52:21 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Wen-Jun Tan, Yang-Zhao Ren, Zheng-Hang Yu, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Maria-Grazia Bernardini (INAF-OAB, LUPM) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by GRB 260114A (SVOM trigger reference: sb26011401) at 2026-01-14T11:40:26.400 (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #43395), Swift/BAT (R. A. J. Eyles-Ferris et al., GCN #43396) and GECAM-B (Ren et al., GCN #43402). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a single pulse with a T90 of 0.38 +0.06/-0.04 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb260114A.png In addition, the position of this burst, as determined by Swift/BAT (RA = 74.602, Dec = -7.994, Error = 3.3 arcseconds, GCN #43396), is located at about 94 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0-0.12 to T0+0.3 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -0.43 +0.13/-0.11 and the cutoff energy, parameterized as Epeak, is 954 +134/-120 keV. The event fluence (10-1000 keV) in this time interval is (6.72 +0.23/-0.22)E-06 erg/cm^2. The localization of GRB 260114A in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb260114A_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/GRM point of contact for this burst is: Chen-Wei Wang (IHEP) (cwwang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/43404. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41498] Swift GRB 260114A: Global MASTER-Net observations report
by GCN Circulars 14 Jan '26

14 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43403 SUBJECT: Swift GRB 260114A: Global MASTER-Net observations report DATE: 26/01/14 17:42:32 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 260114A ( R. A. J. Eyles-Ferris et al., GCN 43396) errorbox 13094 sec after notice time and 13137 sec after trigger time at 2026-01-14 15:19:23 UT, with upper limit up to 20.0 mag. The observations began at zenith distance = 60 deg. The sun altitude is -52.6 deg. The galactic latitude b = -28 deg., longitude l = 207 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3101880 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 13167 | MASTER-Tunka | C | 60 | 19.4 | 13227 | MASTER-Tunka | C | 180 | 20.0 | Coadd 13241 | MASTER-Tunka | C | 60 | 15.5 | 13241 | MASTER-Tunka | C | 60 | 19.2 | 13313 | MASTER-Tunka | C | 60 | 19.1 | 13389 | MASTER-Tunka | C | 60 | 14.9 | 13389 | MASTER-Tunka | C | 60 | 19.1 | 13449 | MASTER-Tunka | C | 180 | 19.8 | Coadd 13461 | MASTER-Tunka | C | 60 | 15.2 | 13461 | MASTER-Tunka | C | 60 | 19.2 | 13536 | MASTER-Tunka | C | 60 | 17.8 | 13536 | MASTER-Tunka | C | 60 | 19.0 | 13611 | MASTER-Tunka | C | 60 | 18.7 | 13611 | MASTER-Tunka | C | 60 | 19.3 | 14458 | MASTER-Tunka | C | 60 | 19.1 | 14458 | MASTER-Tunka | C | 60 | 18.6 | 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/43403. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41497] GRB 260114A: GECAM-B observation of a short burst
by GCN Circulars 14 Jan '26

14 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43402 SUBJECT: GRB 260114A: GECAM-B observation of a short burst DATE: 26/01/14 17:19:48 GMT FROM: renyz16607(a)163.com Yang-Zhao Ren, Chen-Wei Wang, Wen-Jun Tan, Zheng-Hang Yu, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered in-flight by GRB 260114A, at 2026-01-14T11:40:26.350 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #43395), and Swift/BAT (Eyles-Ferris et al., GCN #43396). According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of a pulse with a duration (T90) of 0.38 +0.18/-0.08 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb260114A.png The time-averaged spectrum from T0-0.1 to T0+0.4 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -0.26 +0.16/-0.30 and the cutoff energy, parameterized as Epeak, is 700 +93/-96 keV. The event fluence (10-1000 keV) in this time interval is (5.03 +0.34/-0.31)E-06 erg/cm^2. The 'Amati' relation diagram of GRB 260114A is shown at: https://www.bursthub.cn//admin/static/gecambgrb260114A_amati.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/43402. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41496] GRB 260114A: Mondy optical observations
by GCN Circulars 14 Jan '26

14 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43401 SUBJECT: GRB 260114A: Mondy optical observations DATE: 26/01/14 16:57:54 GMT FROM: Alexei Pozanenko at IKI, Moscow <grb.alex(a)gmail.com> A. Volnova (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (HSE, IKI) report on behalf of IKI-GRB-FuN: We observed the field of GRB 260114A (Eyles-Ferris et al., GCN 43396; Fermi GBM team, GCN 43395; Bissaldi et al., GCN 43400) with the AZT-33IK 1.5m telescope of the Mondy observatory starting on 2026-01-14 (UT) 12:17:27 in R filter. Within the Swift/XRT error circle (Eyles-Ferris et al., GCN 43396) we detect the optical counterpart (Li et al., GCN 43398). Preliminary photometry is the following: Date UT start t-T0 Exp. Filter Obj. Err. UL Site/Telescope (mid,days) (n*s) (3sigma) 2026-01-14 12:17:27 0.08360 37*120 R 20.41 0.15 21.6 The photometry is calibrated using USNO-B1.0 stars and is not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43401. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41495] GRB 260114A: Fermi GBM observation
by GCN Circulars 14 Jan '26

14 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43400 SUBJECT: GRB 260114A: Fermi GBM observation DATE: 26/01/14 16:32:46 GMT FROM: Elisabetta Bissaldi at Politecnico and INFN Bari <elisabetta.bissaldi(a)ba.infn.it> E. Bissaldi (Politecnico and INFN Bari) reports on behalf of the Fermi GBM Team: "At 11:40:26.31 UT on 14 January 2026, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 260114A (trigger 790083631 / 260114486), which was also detected by the Swift/BAT (Eyles-Ferris et al. 2026, GCN 43396). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 70 degrees. The GBM light curve consists of a bright emission episode with a duration (T90) of about 320 ms (50-300 keV). The time-averaged spectrum from T0-0.064 s to T0+0.384 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.07 +/- 0.06 and the cutoff energy, parameterized as Epeak, is 583 +/- 25 keV. The event fluence (10-1000 keV) in this time interval is (4.87 +/- 0.12)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0+0.064 s in the 10-1000 keV band is 35.9 +/- 1.4 ph/s/cm^2. A Band function fits the spectrum equally well with Epeak = 575 +/- 29 keV, alpha = -0.06 +/- 0.06, and beta = -3.5 +/- 0.6. 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/43400. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41494] GRB 260112B: GECAM-B observation
by GCN Circulars 14 Jan '26

14 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43399 SUBJECT: GRB 260112B: GECAM-B observation DATE: 26/01/14 15:16:26 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 on-ground by GRB 260112B, at 2026-01-12T20:45:55.000 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #43380). According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of 15.9 +1.7/-2.2 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb260112B.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/43399. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41493] GRB 260114A: GMG Optical Observation
by GCN Circulars 14 Jan '26

14 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43398 SUBJECT: GRB 260114A: GMG Optical Observation DATE: 26/01/14 13:39:46 GMT FROM: Rui-Zhi Li at Yunnan Observatories, CAS <liruizhi(a)ynao.ac.cn> R.-Z. Li, J. Mao, B.-T. Wang, F.-F. Song, Y. Wang, J.-G. Wang and B. Wang (YNAO, CAS) report: We observed the field of GRB 260114A (Eyles-Ferris et al., GCN 43396; Fermi GBM team, GCN 43395; T0 at 2026-01-14T11:40:26) using the GMG-2.4m telescope at the Lijiang Observatory. The observation began at 2026-01-14T12:18:52, about 0.64 hours after the trigger. We detected an optical source within the Swift/XRT error circle (Eyles-Ferris et al., GCN 43396). The preliminary analysis results for this source are presented below. +---------------+------------+----------+--------------+----------------+ | Tmid-T0 [h] | Exp. [s] | Filter | Mag | 5-sigma U.L. | +===============+============+==========+==============+================+ | 0.81 | 1200 | r | 21.19 ± 0.06 | 22.6 | +---------------+------------+----------+--------------+----------------+ We note that an extended galaxy (R.A., Dec. = 04:58:23.41, −08:00:49.6; r = 21.47 mag in the Pan-STARRS DR2 image) is located within the Swift/XRT error circle. Three objects within the Swift/XRT error circle have photometric redshifts of z ~ 0.5 in the DESI Legacy Surveys. Given the poor seeing conditions at the Lijiang Observatory, no additional candidate sources in our image were found within the Swift/XRT error circle. The given magnitudes are derived based on calibration against Pan-STARRS1 field stars, and are not corrected for the expected Galactic foreground extinction, corresponding to a reddening of E(B-V) = 0.0685 mag in the direction of the optical source (Schlafly & Finkbeiner 2011). View this GCN Circular online at https://gcn.nasa.gov/circulars/43398. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41492] Fermi-LAT Gamma-ray Observations of IceCube-260111A
by GCN Circulars 14 Jan '26

14 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43397 SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-260111A DATE: 26/01/14 12:42:22 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 IC-260111A neutrino event (GCN 43374) 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 26-01-11 at 20:10:33.91 UTC (T0) with J2000 position RA = 70.88 (+1.55, -1.40) deg, Decl. = 34.59 (+0.76, -0.64 ) deg 90% PSF containment. One cataloged >100 MeV gamma-ray source is located within the 90% IC-260111A localization error, at a distance of roughly 0.3 deg (Fourth Fermi-LAT catalog, 4FGL-DR4, The Fermi-LAT collaboration 2023, arXiv:2307.12546). This is the object 4FGL J0444.6+3425 associated with the blazar of uncertain type B2 0441+34. Based on a preliminary analysis of the LAT data over the timescale of one day and one month prior T0, this object is not significantly detected at gamma-rays. 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 IC-260111A 90% confidence localization. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IceCube best-fit position, the >100 MeV flux upper limit (95% confidence) is 3.0e-10 ph cm^-2 s^-1 for ~17-years (2008-08-04 / T0), <9.3e-09 (1.6 e-07) 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/43397. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41491] GRB 260114A: Swift detection of a short burst
by GCN Circulars 14 Jan '26

14 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43396 SUBJECT: GRB 260114A: Swift detection of a short burst DATE: 26/01/14 11:55:28 GMT FROM: Rob Eyles-Ferris at U of Leicester <raje1(a)leicester.ac.uk> R. A. J. Eyles-Ferris (U Leicester), J. A. Kennea (PSU), H. A. Krimm (NSF), N. P. M. Kuin (UCL-MSSL), K. L. Page (U Leicester) and B. Sbarufatti (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team: At 11:40:26 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 260114A (trigger=1440319). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 74.602, -7.994 which is RA(J2000) = 04h 58m 25s Dec(J2000) = -07d 59' 37" 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 0.5 sec. The peak count rate was ~16000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 11:42:28.4 UT, 122.2 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 74.59830, -8.01433 which is equivalent to: RA(J2000) = 04h 58m 23.59s Dec(J2000) = -08d 00' 51.6" with an uncertainty of 3.3 arcseconds (radius, 90% containment). This location is 74 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. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 5.72 x 10^20 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 126 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 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 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 0.080. Burst Advocate for this burst is R. A. J. Eyles-Ferris (raje1 AT leicester.ac.uk). 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/43396. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41490] GRB 260114A: Swift detection of a short burst
by GCN Circulars 14 Jan '26

14 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43396 SUBJECT: GRB 260114A: Swift detection of a short burst DATE: 26/01/14 11:55:28 GMT FROM: Rob Eyles-Ferris at U of Leicester <raje1(a)leicester.ac.uk> R. A. J. Eyles-Ferris (U Leicester), J. A. Kennea (PSU), H. A. Krimm (NSF), N. P. M. Kuin (UCL-MSSL), K. L. Page (U Leicester) and B. Sbarufatti (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team: At 11:40:26 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 260114A (trigger=1440319). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 74.602, -7.994 which is RA(J2000) = 04h 58m 25s Dec(J2000) = -07d 59' 37" 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 0.5 sec. The peak count rate was ~16000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 11:42:28.4 UT, 122.2 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 74.59830, -8.01433 which is equivalent to: RA(J2000) = 04h 58m 23.59s Dec(J2000) = -08d 00' 51.6" with an uncertainty of 3.3 arcseconds (radius, 90% containment). This location is 74 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. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 5.72 x 10^20 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 126 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 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 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 0.080. Burst Advocate for this burst is R. A. J. Eyles-Ferris (raje1 AT leicester.ac.uk). 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/43396. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41489] GRB 260114A: Fermi GBM Final Real-time Localization
by GCN Circulars 14 Jan '26

14 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43395 SUBJECT: GRB 260114A: Fermi GBM Final Real-time Localization DATE: 26/01/14 11:51:03 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 11:40:26 UT on 14 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260114A (trigger 790083631.309942 / 260114486). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 74.1, Dec = -15.2 (J2000 degrees, equivalent to J2000 04h 56m, -15d 11'), with a statistical uncertainty of 1.7 degrees. The angle from the Fermi LAT boresight is 63.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260114486/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260114486/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260114486/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43395. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41488] EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
by GCN Circulars 14 Jan '26

14 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43394 SUBJECT: EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare DATE: 26/01/14 00:30:43 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Z. Kang (CHO), C. Wu, 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 trigger 01709251266 detected by EP/WXT (Wang et al., GCN 43383) with LATIOS on SVOM/C-GFT. Observations started at 2026-01-12T18:15:35 UTC, ~5.63 min after the trigger. A sequence of g-, r-, and i-band images was obtained over ~1.5 hr. Photometry of the suggested flare star LSPM J0924+304 shows a decline from ~13.3 to ~14.0 mag in g-band over ~90 min. The fading was initially fast, then slowed, and was flatter in the r and i bands. This confirms the EP X-ray trigger is associated with a stellar flare. We thank the observation assistants Yin-Huai Hao and 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/43394. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41487] IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 13 Jan '26

13 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43393 SUBJECT: IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube DATE: 26/01/13 20:32:34 GMT FROM: Alicia Mand at IceCube/UW-Madison <aemand(a)wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-260111A (https://gcn.nasa.gov/circulars/43374) in a time range of 1000 seconds centered on the alert event time (2026-01-11 20:02:13.888 UTC to 2026-01-11 20:18:53.888 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-260111A. We report a p-value of 1.00 in this time window. IceCube’s sensitivity to neutrino point sources with an E^-2.5 spectrum, expressed as E^2 dN/dE evaluated at 1 TeV, is 1.4e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-260111A in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 2e+02 GeV and 6e+04 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2026-01-10 20:10:33.888 UTC to 2026-01-12 20:10:33.888 UTC). In this case, we report a p-value of 1.00, consistent with no significant excess of track events. IceCube’s sensitivity to neutrino point sources with an E^-2.5 spectrum, expressed as E^2 dN/dE evaluated at 1 TeV, ranges from 1.6e-01 to 1.7e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-260111A in a 2 day time window. 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. [1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021) View this GCN Circular online at https://gcn.nasa.gov/circulars/43393. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41486] Swift GRB260113.43: Global MASTER-Net observations report
by GCN Circulars 13 Jan '26

13 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43392 SUBJECT: Swift GRB260113.43: Global MASTER-Net observations report DATE: 26/01/13 18:52:27 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 GRB260113.43 (trigger No 1439093,23h 49m 29.21s , +09d 02m 28.7s, R=0.05) errorbox 30419 sec after notice time and 30437 sec after trigger time at 2026-01-13 18:41:23 UT, with upper limit up to 17.8 mag. Observations started at twilight. The observations began at zenith distance = 68 deg. The sun altitude is -10.6 deg. The galactic latitude b = -51 deg., longitude l = 99 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3101140 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 30527 | MASTER-SAAO | C | 180 | 13.4 | 30739 | MASTER-SAAO | C | 180 | 17.8 | 30739 | MASTER-SAAO | C | 180 | 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/43392. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41485] EP260110a: NOT and GTC Optical and Near-Infrared Observations
by GCN Circulars 13 Jan '26

13 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43391 SUBJECT: EP260110a: NOT and GTC Optical and Near-Infrared Observations DATE: 26/01/13 16:52:27 GMT FROM: Gregory Corcoran at University College Dublin <gregory.corcoran(a)ucdconnect.ie> G. Corcoran (UCD), P. G. Jonker (Radboud), J. Sanchez-Sierras (Radboud), A. Martin-Carrillo (UCD), J. A. Quirola-Vasquez (Radboud), A. van Hoof (Radboud), D. Mata Sanchez (IAC), D. Slumstrup (GTC), N. Castro Rodríguez (GTC), V. Vuolteenaho (NOT and Oulu Univ.) report on behalf of a larger collaboration: We observed the field of the fast X-ray transient EP260110a (Zhang et al., GCNs 43363, 43367) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera as well as in the near infrared with the Gran Telescopio Canarias (GTC) equipped with the EMIR instrument. Our observations consisted of two epochs of 3 x 300 s in SDSS-r band and 5 x 200 s in SDSS-z, taken from the NOT, and a single epoch in H with a total exposure time of 1280 s taken from the GTC. Performing image subtraction with PyZOGY on our r-band stacked images and visually comparing the other bands to a stack of archival r-band CFHT images we do not detect any new sources within the EP/FXT uncertainty region in any of our images. We obtain the following upper limits: | Mid time (UT) | Time since trigger (hr) | Band | 3 sigma UL (AB) | | ----- | ----- | ----- | ----- | | 2026-01-11 01:46:32 | 13.80 | r | 23.5 | | 2026-01-11 02:04:27 | 14.10 | z | 22.3 | | 2026-01-11 06:35:44 | 19.02 | H | 23.3 | | 2026-01-12 03:03:04 | 39.08 | r | 24.2 | | 2026-01-12 03:20:59 | 39.38 | z | 22.7 | The r and z band upper limits were calibrated using nearby stars from the Pan-STARRS catalog while the 2MASS catalog was used for the H-band observations and the photometry is not corrected for Galactic extinction. Our upper limits are consistent with Perez-Garcia et al. (GCN 43364), Kang et al. (GCN 43365), Antier et al. (GCN 43366), Zheng et al. (GCN 43368), Lipunov et al. (GCN 43372), Li et al. (GCN 43375), and Zhu et al. (GCN 43390). We note the presence of two faint sources within the EP/FXT uncertainty region in both our r- and H-band images, which are also seen in the archival CFHT imagery. While no residual is visible at their position in the r-band subtraction, due to the lack of sufficiently deep H-band templates we cannot test for NIR variability at this time. View this GCN Circular online at https://gcn.nasa.gov/circulars/43391. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41484] EP260110a: TRT optical upper limits
by GCN Circulars 13 Jan '26

13 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43390 SUBJECT: EP260110a: TRT optical upper limits DATE: 26/01/13 16:28:35 GMT FROM: Zipei Zhu at NAOC <zpzhu(a)nao.cas.cn> Z.P. Zhu (NAOC), S. Tinyanont, K. Noysena, K. Chanchaiworawit, S. Tinyanont (NARIT), J. An, X. Liu, S.Q. Jiang, L.B. He, N.C. Sun, W.X. Li, D. Xu (NAOC), S.Y. Fu (HUST) report on behalf of a large collaboration: We observed the field of EP260110a detected by the Einstein Probe (EP) (Zhang et al., GCN 43367), using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at Sierra Remote Observatories in California. We obtained several 360 s frames in the R filter. Observations started at 07:38:55 UTC on 2026-01-11, i.e., 0.44 day after the EP/WXT trigger time. No new source is detected within or at the border of the EP/FXT error region (Zhang et al., GCN 43363), being consistent with the non-detection reported at other telescopes (Perez-Garcia et al., GCN 43364; Kang et al., GCN 43365; Antier et al., GCN 43366; Zheng et al., GCN 43368; Lipunov et al., GCN 43372; Li et al., GCN 43375). From the stacked images we obtain the following 5-sigma upper limits in Vega magnitude: | Mid-time(d) | filter | upper limit | site | | ------------- | -------- | ------------- | ------ | | 0.46 | R | > 19.6 | SRO | | 1.45 | R | > 20.9 | SRO | | 2.44 | R | > 21.0 | SRO | calibrated using nearby stars from the Pan-STARRS DR1 catalog and are not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43390. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41483] Konus-Wind detection of GRB 260101A
by GCN Circulars 13 Jan '26

13 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43389 SUBJECT: Konus-Wind detection of GRB 260101A DATE: 26/01/13 15:31:48 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The 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) triggered Konus-Wind at T0=3419.619 s UT (00:56:59.619). The burst light curve shows a multipeaked structure which starts at ~T0-26 s and has a total duration of ~30 s. The emission is seen up to ~1 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260101_T03419/ As observed by Konus-Wind, the burst had the total fluence of 7.47(-0.65,+0.77)x10^-6 erg/cm2, and the 64-ms peak flux, measured from T0+0.210 s, of 1.95(-0.42,+0.44)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). Since the main fraction of burst counts 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 T0-26.365 s to T0+3.168 s) by a power law with exponential cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), yields alpha = -1.50(-0.11,+0.13) and Ep = 176(-30,+45) keV. Modelling the KW 3-channel spectrum near the maximum count rate (measured from T0-5.757 s to T0+3.168 s) by the CPL model yields alpha = -1.44(-0.15,+0.20) and Ep = 129(-18,+25) keV. Assuming the redshift z=2.623 (de Ugarte Postigo et al., GCN 43287) and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the following rest-frame parameters: the isotropic energy release E_iso is 1.21(-0.11,+0.12)x10^53 erg, the peak luminosity L_iso is 1.15(-0.25,+0.26)x10^53 erg/s, the rest-frame peak energy of the time-averaged spectrum Ep,i,z is 637(-109,+162) keV and the spectrum near the maximum count rate Ep,p,z is 467(-65,+90) keV. With the obtained estimates, GRB 260101A is inside 68% prediction bands for both the 'Amati' and the 'Yonetoku' relations derived for the sample of >300 long KW GRBs with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021), see http://www.ioffe.ru/LEA/GRBs/GRB260101_T03419/GRB260101A_rest_frame.pdf 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/43389. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41482] GRB 260111A: Swift-XRT observations
by GCN Circulars 13 Jan '26

13 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43388 SUBJECT: GRB 260111A: Swift-XRT observations DATE: 26/01/13 11:01:35 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> S. Lanava (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), S. Dichiara (PSU), J.A. Kennea (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Swift/BAT-GUANO (Ronchini et al., GCN 43377) and Fermi/GBM (Fermi GBM team, GCN 43370; Palafox et al., GCN 43384) detected burst GRB 260111A, collecting 2.8 ks of Photon Counting (PC) mode data between T0+94.3 ks and T0+104.8 ks. One uncatalogued X-ray source has been detected within the estimated 3-sigma Swift/BAT error region (493 arcsec), it is below the RASS limit and shows no definitive signs of fading. A source consistent with the position of XRT source 2 has been reported in the optical with COLIBRÍ, suggesting it could be the GRB afterglow (Ducoin et al., GCN 43386). Details of this source are given below: Source 2: RA (J2000.0): 229.5858 = 15h 18m 20.60s Dec (J2000.0): +51.9736 = +51d 58' 24.8" Error: 6.3 arcsec (radius, 90% conf.) Count-rate: (5.6 [+2.4, -1.9])e-3 ct s^-1 Distance: 27 arcsec from Swift/BAT position. Flux: (1.56 [+0.66, -0.53])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) A catalogued source was also detected within the estimated 3-sigma Swift/BAT error region (493 arcsec). 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/00021897. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43388. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41481] Swift Trigger 1439093: is probably not GRB 260113A
by GCN Circulars 13 Jan '26

13 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43387 SUBJECT: Swift Trigger 1439093: is probably not GRB 260113A DATE: 26/01/13 10:47:55 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> R. Gupta (NASA GSFC), A. Y. Lien (U Tampa), K. L. Page (U Leicester), D. M. Palmer (LANL), C. Salvaggio (INAF-OAB) and B. Sbarufatti (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team: At 10:14:06 UT, the Swift Burst Alert Telescope (BAT) triggered and located an event (trigger=1439093). Swift slewed immediately to the location. The BAT on-board calculated location is RA, Dec 357.372, +9.041 which is RA(J2000) = 23h 49m 29s Dec(J2000) = +09d 02' 29" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). We only have limited BAT light curve information at this moment, current light curve showed some potential pulse-like structure in the low energy band (15-25 keV), but nothing significant in other energy bands. Therefore, the pulse-like structure may be due to noisy detectors. Further ground analysis is required to determine the nature of this trigger. The XRT began observing the field at 10:16:22.6 UT, 136.1 seconds after the BAT trigger. No source was detected in 1.5 ks of promptly downlinked data. UVOT took a finding chart exposure of 150 seconds with the White filter starting 139 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 25% of the BAT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the BAT 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 0.098. Due to the marginal detection of this event in the BAT Image (6.5 sigma) and the lack of the an XRT counterpart detection, we believe that this trigger is most likely to be a statistical fluctuation in the instrument and not a true astrophysical event. Determination of the reality of this event will require the full downlinked dataset. We retain the name GRB 260113A for this event to avoid confusion. Burst Advocate for this burst is R. Gupta (rahulbhu.c157 AT gmail.com) 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/43387. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41480] GRB 260111A: COLIBRÍ optical afterglow candidate
by GCN Circulars 13 Jan '26

13 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43386 SUBJECT: GRB 260111A: COLIBRÍ optical afterglow candidate DATE: 26/01/13 07:27:49 GMT FROM: J.-G. Ducoin at CPPM <ducoin(a)cppm.in2p3.fr> Jean-Grégoire Ducoin (CPPM), Diego López-Cámara (UNAM), Edilberto Aguilar-Ruiz (UNAM), Francesco Magnani (CPPM), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (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), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Asuka Kuwata (UNAM), Nikos Mandarakas (LAM), Kin Ocelotl López (UNAM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We imaged the field of the Swift/Fermi GRB 260111A (Fermi GBM Team, GCN 43370, GCN 43384; Ronchini et al., GCN 43377) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-01-12 10:06 to 13:26 UTC (from 17.55 to 20.88 hours after the trigger) and obtained 145 minutes of simultaneous exposure in the r and z filters. The data were reduced, coadded, calibrated, and analyzed with the COLIBRÍ pipeline, and were also analyzed 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 Legacy Survey as template, consistent with the BAT/GUANO 5 arcmin error circle (Ronchini et al., GCN Circ. 43377) and the XRT source #2 (Evans et al., GCN 43379) at : RA(J2000) = 15:18:20.830 = 229.58679 degrees Dec(J2000) = +51:58:25.82 = 51.97384 degrees with an uncertainty of 0.5 arcsec. The preliminary magnitude derived for that source is: r = 22.87 +/- 0.07 z = 22.33 +/- 0.14 We cannot confirm that the source is fading, however its proximity to XRT #2 suggests it could be the afterglow of GRB 260111A. This detection is very significantly fainter than the upper limit measured with GOTO (Gompertz et al., GCN 43381), and thus compatible with it. We encourage further follow-up of this candidate. 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/43386. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41479] GRB 260111A: GECAM-B observation of a burst
by GCN Circulars 13 Jan '26

13 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43385 SUBJECT: GRB 260111A: GECAM-B observation of a burst DATE: 26/01/13 06:22:50 GMT FROM: Xinghao Luo at IHEP <2952704891(a)qq.com> Xing-Hao Luo, Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered on-ground by GRB 260111A, at 2026-01-11T16:33:15.000 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #43370). According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of 33 +13/-12 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb260111A.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/43385. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41478] GRB 260111A: Fermi GBM Observation
by GCN Circulars 13 Jan '26

13 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43384 SUBJECT: GRB 260111A: Fermi GBM Observation DATE: 26/01/13 02:51:56 GMT FROM: Eva MP at INAOE <eva.palafox(a)gmail.com> Eva Palafox (INAOE) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 16:33:14.01 UT on 11 January 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260111A (trigger 789841999/260111690). which was also detected by Swift/BAT (S. Ronchini et al. 2026, GCN 43377). The Fermi GBM on-ground location (GCN 43370) is consistent with the Swift/BAT position. The angle from the Fermi LAT boresight is 14.4 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 31 s (50-300 keV). The time-averaged spectrum from T0-18 to T0+52 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.7 +/- 0.3 and the cutoff energy, parameterized as Epeak, is 140 +/- 30 keV. The event fluence (10-1000 keV) in this time interval is (2.3 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.70 s in the 10-1000 keV band is 2.4 +/- 0.2 ph/s/cm^2. 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/43384. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41477] The EP-WXT trigger 01709251266 is likely a flaring star
by GCN Circulars 13 Jan '26

13 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43383 SUBJECT: The EP-WXT trigger 01709251266 is likely a flaring star DATE: 26/01/13 02:32:51 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> B.T. Wang (YNAO, CAS), Q. J. Huang, R. Shi (PMO, CAS), H.Z. Wu (HUST), K. R. Ni (CCNU) and H. Sun (NAO,CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709251266 at the time of 2026-01-12T18:09:57, is likely a stellar flare associated with LSPM J0924+3041. 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 7.3x10^30 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/43383. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41476] Swift Trigger 1434591 is not a GRB
by GCN Circulars 12 Jan '26

12 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43382 SUBJECT: Swift Trigger 1434591 is not a GRB DATE: 26/01/12 22:57:28 GMT FROM: Tyler Parsotan at NASA GSFC <tyler.parsotan(a)nasa.gov> T. M. Parsotan (GSFC) report on behalf of the Neil Gehrels Swift Observatory Team: Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT trigger #1434591 (Parsotan et al GCN Circ. 43359). This trigger is due to noise, with no significant emission detected in the mask-weighted light curve or in the reconstructed image. No confirmed counterpart is found in the XRT or UVOT data within the BAT error circle, indicating that the trigger is not a real astrophysical event. View this GCN Circular online at https://gcn.nasa.gov/circulars/43382. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41475] GRB 260111A: GOTO optical upper limits
by GCN Circulars 12 Jan '26

12 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43381 SUBJECT: GRB 260111A: GOTO optical upper limits DATE: 26/01/12 21:35:29 GMT FROM: Ben Gompertz at U of Birmingham <b.gompertz(a)bham.ac.uk> B. P. Gompertz, D. O’Neill, A. Kumar, G. Ramsay, R. Starling, K. Ackley, M. Dyer, J. Lyman, K. Ulaczyk, D. Steeghs, D. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. Kotak, R. Breton, J. Casares, L. Nuttall, B. Godson, T. Killestein, S. Belkin, and 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 GRB 260111A (Fermi GBM Team, GCN 43370; Ronchini et al., GCN 43377). Observations of the GBM localisation region began at 2026-01-12 02:58:56 UT, (+10.4h post trigger) and continued through to 2026-01-12 06:46:03 UT (+14.2h post trigger). Each observation consisted of 4x90 s exposures in the GOTO L-band (400-700 nm). 109 images were taken, across 9 unique pointings, covering 209.3 square degrees within the 90% localisation contour. ~78.4% of the total 2D localisation probability was covered, with an average 5-sigma depth of 20.0 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. The GUANO localisation region (Ronchini et al., GCN 43377) was fully covered in an epoch taken at 06:37:29 UT on 2026-01-12 (+14.1h post trigger). No new sources were identified to a 5-sigma limiting AB magnitude of L > 20.1 mag. 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/43381. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41474] GRB 260112B: Fermi GBM Final Real-time Localization
by GCN Circulars 12 Jan '26

12 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43380 SUBJECT: GRB 260112B: Fermi GBM Final Real-time Localization DATE: 26/01/12 20:56:32 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 20:45:51 UT on 12 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260112B (trigger 789943556.635812 / 260112865). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 238.6, Dec = -3.5 (J2000 degrees, equivalent to J2000 15h 54m, -3d 30'), with a statistical uncertainty of 7.8 degrees. The angle from the Fermi LAT boresight is 34.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260112865/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260112865/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260112865/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43380. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41473] GRB 260112B: Fermi GBM Final Real-time Localization
by GCN Circulars 12 Jan '26

12 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43380 SUBJECT: GRB 260112B: Fermi GBM Final Real-time Localization DATE: 26/01/12 20:56:32 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 20:45:51 UT on 12 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260112B (trigger 789943556.635812 / 260112865). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 238.6, Dec = -3.5 (J2000 degrees, equivalent to J2000 15h 54m, -3d 30'), with a statistical uncertainty of 7.8 degrees. The angle from the Fermi LAT boresight is 34.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260112865/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260112865/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260112865/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43380. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41472] GRB 260111A: Swift ToO observations
by GCN Circulars 12 Jan '26

12 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43379 SUBJECT: GRB 260111A: Swift ToO observations DATE: 26/01/12 18:44:34 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 Swift/BAT-detected event GRB 260111A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021897 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 Swift/BAT 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/43379. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41471] GRB 251230A: Mondy Optical Observations
by GCN Circulars 12 Jan '26

12 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43378 SUBJECT: GRB 251230A: Mondy Optical Observations DATE: 26/01/12 15:10:09 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> N. Pankov (HSE, IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova (IKI) report on behalf of IKI-GRB-FuN: We performed optical observations of the field of GRB 251230A (Lanava et al., GCN 43252; Wang et. al, GCN 43259; Osborne et. al, GCN 43263; Wang et. al, GCN 43272; Sbarrato et al., GCN 43275; Guo et. al, GCN 43299; Guo et. al, GCN 43301) in the R filter with the AZT-33IK 1.5-meter telescope of the Sayan Solar Observatory (SSO Mondy). The observations began on 2025-12-30 19:36:42 UT, i.e. ~0.77 days since trigger. The optical counterpart (Li et al., GCN 43255; Busmann et al., GCN 43258; Masi et al., GCN 43260; Ghosh et al., GCN 43262; Ma et al., GCN 43265; He et al., GCN 43269; Breeveld et. al, GCN 43271; He et al., GCN 43280; Antier et. al, GCN 43281; Ma et al., GCN 43282; Chatterjee et. al, GCN 43321) is not detected in the co-add image. The preliminary photometry and observation details are provided below: Date UT start t-T0 Exp. Filter OT Err. UL (mid, days) (s) (3sigma) 2025-12-30 19:36:42 0.77001 15*120 R n/d n/d 20.4 The photometry was calibrated using nearby stars from USNO-B1.0 and is not corrected for the Galactic extinction. The obtained results do not contradict the measurements reported by other teams, including upper limits (Starling et. al, GCN 43267; Tak et al., GCN 43270; Gupta et. al, GCN 43277; Sankar et al., GCN 43279). View this GCN Circular online at https://gcn.nasa.gov/circulars/43378. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41470] GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
by GCN Circulars 12 Jan '26

12 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43377 SUBJECT: GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst DATE: 26/01/12 08:48:14 GMT FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu> Samuele Ronchini (GSSI), Aaron Tohuvavohu (Cosmic Frontier), James DeLaunay (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (Northwestern) report: Swift/BAT did not localize GRB 260111A onboard (T0: 2026-01-11T16:33:14.01 UTC, Fermi GCN 43370). The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The position is found with the newly developed pipeline BAT-GLIMPSE: Gamma-ray Localization using Imaging and Mosaic techniques for Pointing and Slew Epochs (Ronchini et. al, in prep). The pipeline makes use of the tools from BatAnalysis (Parsotan et al. 2025). The source was detected with an SNR = 19.7 in a 8.192 s analysis time bin starting at t0 - 4.096 s. Independently, the BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), confirms the detection and position of the burst in a 8.192 s analysis time bin starting at T0 - 4.096 s with a sqrt(TS) of 36.98. An arcminute localization is found with DeltaLLHOut of 317.21 and a DeltaLLHPeak of 302.45. See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretations of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. The NITRATES and BAT-GLIMPSE positions are compatible. The BAT position is: RA, Dec = 229.57340, 51.97470 deg which is RA(J2000) = 15h 18m 17.6s Dec(J2000) = 51d 58' 28.9" with an estimated uncertainty of 5 arcmin radius. More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=789842031 XRT and UVOT follow-up has been requested. Results of follow-up observations will be reported in future circulars. GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/43377. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41469] GRB 260112A: Fermi GBM Final Real-time Localization
by GCN Circulars 12 Jan '26

12 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43376 SUBJECT: GRB 260112A: Fermi GBM Final Real-time Localization DATE: 26/01/12 05:36:31 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 05:25:50 UT on 12 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260112A (trigger 789888355.72541 / 260112226). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 326.5, Dec = -37.8 (J2000 degrees, equivalent to J2000 21h 45m, -37d 47'), with a statistical uncertainty of 18.3 degrees. The angle from the Fermi LAT boresight is 112.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260112226/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260112226/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260112226/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43376. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41468] EP260110a: SVOM/VT optical upper limits
by GCN Circulars 12 Jan '26

12 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43375 SUBJECT: EP260110a: SVOM/VT optical upper limits DATE: 26/01/12 04:40:42 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Y. N. Ma, Z. H. Yao, X. H. Han, J. Wang, P. P. Zhang, Y. Xu, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. R. Xu, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team. SVOM/VT performed ToO observation on the fast X-ray transient EP260110a (Zhang et al., GCN 43363; 43367). The observation started on 2026-01-10T14:29:11 UT (i.e. 2.52 hour post trigger) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channel simultaneously. Inside the error box of the EP-FXT (Zhang et al., GCN 43367) we did not detect any new uncatalogued source, which was consistent with the non detections reported by other groups (Perez-Garcia et al., GCN 43364; Kang et al., GCN 43365; Antier et al., GCN 43366; Zheng et al., GCN 43368; Lipunov et al., GCN 43372). The 3 sigma limits in AB magnitude are derived as below: Mid time | Band | Exposure Time | 3 sigma limit magnitude 4.11 hour VT_B 52*70 sec > 23.5 4.64 hour VT_R 50*70 sec > 23.5 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/43375. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41467] IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
by GCN Circulars 11 Jan '26

11 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43374 SUBJECT: IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 26/01/11 22:48:41 GMT FROM: Giacomo Sommani at Ruhr-Universität Bochum <gsommani(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 26-01-11 at 20:10:33.91 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 0.7434 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/141893_3811884.amon) more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 26-01-11 Time: 20:10:33.91 UT RA: 70.88 (+1.55/-1.4 deg 90% PSF containment) J2000 Dec: 34.59 (+0.76/-0.64 deg 90% PSF containment) J2000 One gamma-ray source from the Fermi 4FGL-DR4 catalog is located within the 90% uncertainty region of this event: 4FGL J0444.6+3425, at RA = 71.16° and Dec = 34.42° (J2000), with an angular separation of 0.29° from the best-fit event position. 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/43374. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41466] IceCube Alert 260111.84: Global MASTER-Net observations report
by GCN Circulars 11 Jan '26

11 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43373 SUBJECT: IceCube Alert 260111.84: Global MASTER-Net observations report DATE: 26/01/11 20:39:22 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the IceCube Alert 260111.84 (trigger No 3811884,04h 44m 30.72s , +35d 03m 43.2s, R=0.51) errorbox 12 sec after notice time and 58 sec after trigger time at 2026-01-11 20:11:32 UT, with upper limit up to 19.2 mag. The observations began at zenith distance = 21 deg. The sun altitude is -64.6 deg. MASTER-Tunka robotic telescope located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the IceCube Alert 260111.84 errorbox 26 sec after notice time and 72 sec after trigger time at 2026-01-11 20:11:46 UT, with upper limit up to 14.1 mag. The observations began at zenith distance = 61 deg. The sun altitude is -44.9 deg. MASTER-SAAO robotic telescope located in South Africa (South African Astronomical Observatory) was pointed to the IceCube Alert 260111.84 errorbox 61 sec after notice time and 107 sec after trigger time at 2026-01-11 20:12:21 UT, with upper limit up to 18.9 mag. The observations began at zenith distance = 67 deg. The sun altitude is -24.8 deg. The galactic latitude b = -6 deg., longitude l = 168 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3100219 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 64 | 2026-01-11 20:11:32 | MASTER-Kislovodsk | (04h 43m 04.86s , +35d 34m 12.2s) | P| | 10 | 15.9 | 64 | 2026-01-11 20:11:32 | MASTER-Kislovodsk | (04h 43m 29.08s , +35d 12m 14.1s) | C | 10 | 16.9 | 89 | 2026-01-11 20:11:32 | MASTER-Kislovodsk | (04h 43m 29.08s , +35d 12m 14.1s) | C | 60 | 18.0 | Coadd 78 | 2026-01-11 20:11:46 | MASTER-Tunka | (04h 43m 38.90s , +35d 16m 36.1s) | P- | 10 | 14.1 | 78 | 2026-01-11 20:11:46 | MASTER-Tunka | (04h 43m 07.38s , +35d 23m 28.3s) | P| | 10 | 13.0 | 99 | 2026-01-11 20:12:02 | MASTER-Kislovodsk | (04h 43m 04.82s , +35d 34m 09.7s) | P| | 20 | 16.4 | 99 | 2026-01-11 20:12:02 | MASTER-Kislovodsk | (04h 43m 29.04s , +35d 12m 12.1s) | C | 20 | 17.4 | 118 | 2026-01-11 20:12:21 | MASTER-SAAO | (04h 42m 05.60s , +34d 48m 35.2s) | C | 20 | 18.0 | 153 | 2026-01-11 20:12:21 | MASTER-SAAO | (04h 42m 05.60s , +34d 48m 35.2s) | C | 90 | 18.9 | 118 | 2026-01-11 20:12:21 | MASTER-SAAO | (04h 40m 03.11s , +35d 04m 27.6s) | C | 20 | 17.8 | 153 | 2026-01-11 20:12:21 | MASTER-SAAO | (04h 40m 03.11s , +35d 04m 27.6s) | C | 90 | 18.8 | 145 | 2026-01-11 20:12:43 | MASTER-Kislovodsk | (04h 43m 28.95s , +35d 12m 09.1s) | C | 30 | 17.8 | 145 | 2026-01-11 20:12:43 | MASTER-Kislovodsk | (04h 43m 04.76s , +35d 34m 06.1s) | P| | 30 | 17.0 | 162 | 2026-01-11 20:13:01 | MASTER-SAAO | (04h 42m 05.86s , +34d 48m 37.9s) | C | 30 | 18.3 | 162 | 2026-01-11 20:13:01 | MASTER-SAAO | (04h 40m 03.42s , +35d 04m 31.2s) | C | 30 | 18.2 | 200 | 2026-01-11 20:13:33 | MASTER-Kislovodsk | (04h 43m 04.72s , +35d 34m 02.5s) | P| | 40 | 16.9 | 200 | 2026-01-11 20:13:33 | MASTER-Kislovodsk | (04h 43m 28.88s , +35d 12m 06.2s) | C | 40 | 17.9 | 255 | 2026-01-11 20:13:33 | MASTER-Kislovodsk | (04h 43m 28.89s , +35d 12m 06.1s) | C | 150 | 18.7 | Coadd 216 | 2026-01-11 20:13:49 | MASTER-SAAO | (04h 42m 06.14s , +34d 48m 40.7s) | C | 40 | 18.4 | 216 | 2026-01-11 20:13:50 | MASTER-SAAO | (04h 40m 03.68s , +35d 04m 34.5s) | C | 40 | 18.2 | 265 | 2026-01-11 20:14:33 | MASTER-Kislovodsk | (04h 43m 04.64s , +35d 33m 58.2s) | P| | 50 | 17.1 | 265 | 2026-01-11 20:14:33 | MASTER-Kislovodsk | (04h 43m 28.78s , +35d 12m 02.4s) | C | 50 | 18.0 | 280 | 2026-01-11 20:14:49 | MASTER-SAAO | (04h 42m 06.49s , +34d 48m 43.7s) | C | 50 | 18.5 | 280 | 2026-01-11 20:14:49 | MASTER-SAAO | (04h 40m 03.97s , +35d 04m 38.1s) | C | 50 | 18.4 | 341 | 2026-01-11 20:15:44 | MASTER-Kislovodsk | (04h 43m 28.69s , +35d 11m 58.8s) | C | 60 | 18.2 | 341 | 2026-01-11 20:15:44 | MASTER-Kislovodsk | (04h 43m 04.53s , +35d 33m 54.1s) | P| | 60 | 17.4 | 354 | 2026-01-11 20:15:58 | MASTER-SAAO | (04h 42m 06.82s , +34d 48m 46.7s) | C | 60 | 18.8 | 354 | 2026-01-11 20:15:58 | MASTER-SAAO | (04h 40m 04.29s , +35d 04m 41.7s) | C | 60 | 18.5 | 432 | 2026-01-11 20:17:05 | MASTER-Kislovodsk | (04h 43m 04.39s , +35d 33m 49.7s) | P| | 80 | 17.4 | 432 | 2026-01-11 20:17:05 | MASTER-Kislovodsk | (04h 43m 28.56s , +35d 11m 55.0s) | C | 80 | 18.4 | 542 | 2026-01-11 20:17:05 | MASTER-Kislovodsk | (04h 43m 28.56s , +35d 11m 54.9s) | C | 300 | 19.2 | Coadd 433 | 2026-01-11 20:17:17 | MASTER-SAAO | (04h 42m 07.12s , +34d 48m 50.4s) | C | 60 | 18.7 | 433 | 2026-01-11 20:17:17 | MASTER-SAAO | (04h 40m 04.61s , +35d 04m 45.6s) | C | 60 | 18.6 | 513 | 2026-01-11 20:18:36 | MASTER-SAAO | (04h 42m 07.48s , +34d 48m 53.0s) | C | 60 | 18.8 | 513 | 2026-01-11 20:18:36 | MASTER-SAAO | (04h 40m 04.97s , +35d 04m 48.8s) | C | 60 | 18.6 | 552 | 2026-01-11 20:18:56 | MASTER-Kislovodsk | (04h 43m 28.37s , +35d 11m 50.5s) | C | 100 | 18.4 | 552 | 2026-01-11 20:18:56 | MASTER-Kislovodsk | (04h 43m 04.21s , +35d 33m 44.7s) | P| | 100 | 17.6 | 592 | 2026-01-11 20:19:55 | MASTER-SAAO | (04h 42m 07.81s , +34d 48m 55.7s) | C | 60 | 18.8 | 592 | 2026-01-11 20:19:55 | MASTER-SAAO | (04h 40m 05.29s , +35d 04m 51.9s) | C | 60 | 18.6 | 683 | 2026-01-11 20:20:56 | MASTER-Kislovodsk | (04h 43m 04.05s , +35d 33m 39.6s) | P| | 120 | 17.6 | 683 | 2026-01-11 20:20:56 | MASTER-Kislovodsk | (04h 43m 28.20s , +35d 11m 46.1s) | C | 120 | 18.4 | 671 | 2026-01-11 20:21:14 | MASTER-SAAO | (04h 42m 08.14s , +34d 48m 58.6s) | C | 60 | 18.8 | 671 | 2026-01-11 20:21:14 | MASTER-SAAO | (04h 40m 05.62s , +35d 04m 55.0s) | C | 60 | 18.7 | 750 | 2026-01-11 20:22:33 | MASTER-SAAO | (04h 42m 08.48s , +34d 49m 01.7s) | C | 60 | 18.8 | 750 | 2026-01-11 20:22:33 | MASTER-SAAO | (04h 40m 05.95s , +35d 04m 58.4s) | C | 60 | 18.6 | 833 | 2026-01-11 20:23:27 | MASTER-Kislovodsk | (04h 43m 27.94s , +35d 11m 41.5s) | C | 120 | 18.5 | 840 | 2026-01-11 20:23:33 | MASTER-Kislovodsk | (04h 43m 03.83s , +35d 33m 33.8s) | P| | 120 | 17.8 | 829 | 2026-01-11 20:23:52 | MASTER-SAAO | (04h 42m 08.82s , +34d 49m 04.0s) | C | 60 | 18.8 | 829 | 2026-01-11 20:23:52 | MASTER-SAAO | (04h 40m 06.27s , +35d 05m 01.0s) | C | 60 | 18.6 | 981 | 2026-01-11 20:25:54 | MASTER-Kislovodsk | (04h 43m 03.62s , +35d 33m 28.6s) | P| | 120 | 17.6 | 981 | 2026-01-11 20:25:54 | MASTER-Kislovodsk | (04h 43m 27.69s , +35d 11m 36.9s) | C | 120 | 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/43373. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41465] EP260110a: Global MASTER-Net observations report
by GCN Circulars 11 Jan '26

11 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43372 SUBJECT: EP260110a: Global MASTER-Net observations report DATE: 26/01/11 19:09:24 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 EP260110a ( EP Team et al., GCN 43363) errorbox 1 days 21876 sec after notice time and 1 days 25310 sec after trigger time at 2026-01-11 18:58:48 UT, with upper limit up to 17.6 mag. The observations began at zenith distance = 62 deg. The sun altitude is -54.1 deg. The galactic latitude b = 51 deg., longitude l = 118 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3099928 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 111800 | 2026-01-11 18:58:48 | MASTER-Kislovodsk | (13h 17m 27.89s , +65d 50m 39.1s) | C | 180 | 16.4 | 111800 | 2026-01-11 18:58:48 | MASTER-Kislovodsk | (13h 17m 45.69s , +65d 27m 35.9s) | C | 180 | 17.6 | 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/43372. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41464] Fermi GRB 260111A: Global MASTER-Net observations report
by GCN Circulars 11 Jan '26

11 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43371 SUBJECT: Fermi GRB 260111A: Global MASTER-Net observations report DATE: 26/01/11 17:15:39 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 260111A ( Fermi GBM team, GCN 43370) errorbox 201 sec after notice time and 236 sec after trigger time at 2026-01-11 16:37:10 UT, with upper limit up to 19.5 mag. The observations began at zenith distance = 70 deg. The sun altitude is -59.9 deg. The galactic latitude b = 56 deg., longitude l = 85 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3100149 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 262 | 2026-01-11 16:37:10 | MASTER-Tunka | (14h 52m 29.86s , +46d 07m 42.6s) | C | 50 | 17.8 | 262 | 2026-01-11 16:37:10 | MASTER-Tunka | (14h 52m 01.47s , +46d 14m 15.0s) | C | 50 | 18.3 | 320 | 2026-01-11 16:38:04 | MASTER-Tunka | (14h 52m 01.36s , +46d 14m 14.7s) | C | 60 | 18.5 | 320 | 2026-01-11 16:38:04 | MASTER-Tunka | (14h 52m 29.78s , +46d 07m 43.0s) | C | 60 | 18.1 | 384 | 2026-01-11 16:39:07 | MASTER-Tunka | (14h 52m 01.23s , +46d 14m 15.1s) | C | 60 | 18.3 | 384 | 2026-01-11 16:39:07 | MASTER-Tunka | (14h 52m 29.72s , +46d 07m 43.8s) | C | 60 | 18.0 | 607 | 2026-01-11 16:42:51 | MASTER-Tunka | (14h 58m 24.98s , +50d 10m 13.5s) | C | 60 | 18.8 | 667 | 2026-01-11 16:42:51 | MASTER-Tunka | (14h 58m 24.98s , +50d 10m 13.5s) | C | 180 | 19.5 | Coadd 607 | 2026-01-11 16:42:51 | MASTER-Tunka | (14h 58m 56.47s , +50d 03m 31.9s) | C | 60 | 18.4 | 670 | 2026-01-11 16:43:54 | MASTER-Tunka | (14h 58m 56.32s , +50d 03m 33.3s) | C | 60 | 18.4 | 670 | 2026-01-11 16:43:54 | MASTER-Tunka | (14h 58m 24.82s , +50d 10m 13.4s) | C | 60 | 18.7 | 734 | 2026-01-11 16:44:58 | MASTER-Tunka | (14h 58m 24.70s , +50d 10m 13.5s) | C | 60 | 18.7 | 734 | 2026-01-11 16:44:58 | MASTER-Tunka | (14h 58m 56.28s , +50d 03m 33.8s) | C | 60 | 18.3 | 797 | 2026-01-11 16:46:01 | MASTER-Tunka | (14h 58m 24.72s , +50d 10m 13.7s) | C | 60 | 18.6 | 797 | 2026-01-11 16:46:01 | MASTER-Tunka | (14h 58m 56.30s , +50d 03m 33.8s) | C | 60 | 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/43371. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41463] GRB 260111A: Fermi GBM Final Real-time Localization
by GCN Circulars 11 Jan '26

11 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43370 SUBJECT: GRB 260111A: Fermi GBM Final Real-time Localization DATE: 26/01/11 16:43:36 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 16:33:14 UT on 11 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260111A (trigger 789841999.012866 / 260111690). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 224.7, Dec = 50.4 (J2000 degrees, equivalent to J2000 14h 58m, 50d 23'), with a statistical uncertainty of 2.7 degrees. The angle from the Fermi LAT boresight is 12.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260111690/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260111690/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260111690/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43370. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41462] Swift trigger 1436759 is not an astrophysical event
by GCN Circulars 11 Jan '26

11 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43369 SUBJECT: Swift trigger 1436759 is not an astrophysical event DATE: 26/01/11 09:22:31 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> R. Brivio (INAF-OAB), A. Mei (INAF-OAB), K. L. Page (U Leicester), T. M. Parsotan (GSFC), C. Salvaggio (INAF-OAB), B. Sbarufatti (INAF-OAB) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: The downlinked data showed no obvious light curve structure, and the lack of the scaled map at the time prevented full verification of the low image significance of the event in the BAT data. The XRT began observing the field at 09:03:15.2 UT, 112.0 seconds after the BAT trigger. No source was detected in 930 s of promptly downlinked data. UVOT took a finding chart exposure of 250 seconds with the U filter starting 172 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 25% of the BAT error circle. The typical 3-sigma upper limit has been about 19.2 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the BAT error circle. The list of sources is typically complete to about 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.111. View this GCN Circular online at https://gcn.nasa.gov/circulars/43369. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41461] EP260110a: KAIT optical upper limit
by GCN Circulars 11 Jan '26

11 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43368 SUBJECT: EP260110a: KAIT optical upper limit DATE: 26/01/11 06:29:36 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 EP260110a (Zhang et al., GCN 43363; 43367) starting at 12:19, Jan 10 UT, about 21 minutes after the burst. A set of 20s, 40s and 60s clear (roughly R) filter images were obtained. In our coadd image, we did not detect any new source within the EP-WXT error circle (Zhang et al., GCN 43367) down to a limiting mag of 21.0 mag (Vega) at a mid-time of 1.0 hours after the burst. Our result is consistent with the upper limit reported by other groups (Perez-Garcia et al., GCN 43364; Kang et al., GCN 43365; Antier et al., GCN43366). View this GCN Circular online at https://gcn.nasa.gov/circulars/43368. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41460] EP260110a: refined analysis of the EP-WXT and EP-FXT observations
by GCN Circulars 11 Jan '26

11 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43367 SUBJECT: EP260110a: refined analysis of the EP-WXT and EP-FXT observations DATE: 26/01/11 04:43:42 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> B. Zhang, J. P. Feng (USTC), Y. Wu (NJU), F. F. Song(YNAO, CAS), A. Li (BNU), C. Y. Wang (THU), G. Y. Zhao (SYSU), Y. Liu (NAOC, CAS) on behalf of the Einstein Probe (EP) team: The fast X-ray transient EP260110a was detected by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Zhang et al., GCN 43363). The refined analysis of the WXT data shows that the event started at T0=2026-01-10T 11:56:58(UTC), and lasted for approximately 85 seconds, after which the WXT light curve was interrupted due to the autonomous follow-up observation. The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 1.59×10^20 cm^-2 and a photon index of 0.83(-0.51/+0.56). The derived average unabsorbed 0.5-4 keV flux is 2.64(-0.88/+1.15)×10^(-10) erg/s/cm^2. The Follow-up X-ray Telescope (FXT) on board EP observed this source autonomously at 2026-01-10T12:00:52(UTC, T0+234 s). The exposure time of this observation is 4576s. On-ground analysis of the FXT data found an uncatalogued source at R.A. = 199.4321, DEC = 65.8490 (J2000) with an uncertainty of about 10 arcsec (radius, 90% C.L. statistical and systematic), which is consistent with the WXT position. The average 0.5-10 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 1.59×10^20 cm^-2 and a photon index of 2.02 (-0.14/+0.14). The derived average unabsorbed 0.5-10 keV flux is 1.52 (-0.19/+0.22)×10^(-12) erg/s/cm^2. We performed one target-of-opportunity (ToO) follow-up observations with FXT at 2026-01-10T16:23:31 (UTC, T0+15,993 s) with an exposure time of 3,032s. The average FXT 0.5-10 keV spectrum of the ToO observation can be fitted with an absorbed power law, with a fixed Galactic hydrogen column density of 1.59×10^20 cm^-2, and a photon index of 2.11 (-0.84/+1.00) . The derived average unabsorbed 0.5-10 keV flux is 1.15 (-0.57/+1.33)×10^(-13) erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. No optical counterpart of EP260110a has been detected so far (Perez-Garcia et al., GCN 43364; Kang et al., GCN 43365; Antier et al., GCN43366) , and further mutil-band follow-up observations are encouraged to explore the nature of EP260110a. 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/43367. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41459] EP 260110a: COLIBRÍ optical observations
by GCN Circulars 10 Jan '26

10 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43366 SUBJECT: EP 260110a: COLIBRÍ optical observations DATE: 26/01/10 17:31:28 GMT FROM: antier(a)ijclab.in2p3.fr Sarah Antier (IJCLAB), Dalya Akl (NYUAD), Edilberto Aguilar-Ruiz (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), 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), Kin Ocelotl López (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): We imaged the field of the EP 260110a using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-01-10 12:17:40 to 13:21 UTC (from 18 min after the trigger) and obtained about 50 minutes of simultaneous exposure in the r and z filters. The data were reduced, coadded, and analyzed with the two COLIBRÍ pipelines, and were also analyzed 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. In the stacked image, we do not detect any new source against Legacy at the WXT and FXT localization error box (Zhang et al., GCN Circ. 43363) down to the following 5-sigma limit: r > 22.8 z > 21.8 This upper limit is consistent with the ones reported by Perez-Garcia et al. GCN Circ. 43364 and Kang at al. Circ. 43365. 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/43366. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41458] EP260110a: SVOM/C-GFT upper limit
by GCN Circulars 10 Jan '26

10 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43365 SUBJECT: EP260110a: SVOM/C-GFT upper limit DATE: 26/01/10 14:51:46 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Z. Kang (CHO), C. WU, L.P. Xin, X.H. Han, P.P. Zhang, X.M. Lu (NAOC), Z.W. Li (CHO), 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 EP260110a, detected by EP/WXT (Zhang et al., GCN 43363), using the LATIOS instrument on the SVOM/C-GFT. Observations started at 2026-01-10T12:20:27 UTC, ~22.07 min after the trigger. A series of i-band images were obtained. After preliminary processing, no credible candidate was detected within the error box provided by EP/FXT (Zhang et al., GCN 43363) in our images. The three-sigma upper limit is: | Date-Obs (mid-time) | Mid_t - T0 (min) | Exposure Time (s) | Band | Upper Limit (AB) | |---------------------|----------------|-------------------|------|------------------| | 2026-01-10T12:20:57 | 22.57 | 2×30 | i | 18.6 | The photometry was calibrated against nearby Pan-STARRS1 stars and no correction for Galactic dust extinction was applied. This result is consistent with Perez-Garcia et al., GCN 43364. We thank the observation assistants Yin-Huai Hao and 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/43365. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41457] EP260110a: SVOM/C-GFT upper limit
by GCN Circulars 10 Jan '26

10 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43365 SUBJECT: EP260110a: SVOM/C-GFT upper limit DATE: 26/01/10 14:51:46 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Z. Kang (CHO), C. WU, L.P. Xin, X.H. Han, P.P. Zhang, X.M. Lu (NAOC), Z.W. Li (CHO), 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 EP260110a, detected by EP/WXT (Zhang et al., GCN 43363), using the LATIOS instrument on the SVOM/C-GFT. Observations started at 2026-01-10T12:20:27 UTC, ~22.07 min after the trigger. A series of i-band images were obtained. After preliminary processing, no credible candidate was detected within the error box provided by EP/FXT (Zhang et al., GCN 43363) in our images. The three-sigma upper limit is: | Date-Obs (mid-time) | Mid_t - T0 (min) | Exposure Time (s) | Band | Upper Limit (AB) | |---------------------|----------------|-------------------|------|------------------| | 2026-01-10T12:20:57 | 22.57 | 2×30 | i | 18.6 | The photometry was calibrated against nearby Pan-STARRS1 stars and no correction for Galactic dust extinction was applied. This result is consistent with Perez-Garcia et al., GCN 43364. We thank the observation assistants Yin-Huai Hao and 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/43365. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41456] EP260110a: BOOTES-5/JGU optical upper limit
by GCN Circulars 10 Jan '26

10 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43364 SUBJECT: EP260110a: BOOTES-5/JGU optical upper limit DATE: 26/01/10 13:26:38 GMT FROM: I. Perez-Garcia at Institute of Astrophysics of Andalusia <ipg(a)iaa.es> I. Perez-Garcia, E. J. Fernandez-Garcia, M. D. Caballero-Garcia, S.-Y. Wu, R. Sanchez-Ramirez, S. Guziy and A. J. Castro-Tirado (IAA-CSIC, Granada), I. M. Carrasco (SMA), M. Gritsevich (Univ. of Helsinki), C. Perez del Pulgar (Univ. of Malaga), Y.-D. Hu (GXU), S. Jeong (ADD, Daejeon), G. Garcia-Segura and D. Hiriart (IA-UNAM, Ensenada), D. R. Xiong (Yunnan Observatories of CAS, Kunming), and W. H. Lee (UNAM, Mexico DF), on behalf of a larger collaboration, report: Following the detection of EP260110a by EP (Zhang et al., GCN 43363), the 0.6m BOOTES-5/JGU robotic telescope at San Pedro Martir Observatory (Mexico) automatically responded to this high-energy event starting on Jan 10, 12:18:31 UT (i.e. 20 min after detection). Nothing is detected down to 17.3 in this first image. On a coadd image (12 x 60sec) at 12:41:13 UT (mid exposure time), nothing is detected down to 20.1 mag (clear filter) within the FXT error region. All photometric calibration was done using Gaia Gmag band. We would like to thank the staff at San Pedro Martir Observatory for their excellent support. View this GCN Circular online at https://gcn.nasa.gov/circulars/43364. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41455] EP260110a: Einstein Probe detection of an X-ray transient
by GCN Circulars 10 Jan '26

10 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43363 SUBJECT: EP260110a: Einstein Probe detection of an X-ray transient DATE: 26/01/10 12:53:09 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> B.Zhang, J. P. Feng (USTC), Y. Wu (NJU), F. F. Song(YNAO, CAS), A. Li (BNU), C. Y. Wang (THU), G. Y. Zhao (SYSU). Y. Liu (NAOC, CAS) on behalf of the Einstein Probe (EP) team: We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP260110a. The transient triggered EP-WXT (ID: 01709251242) at 2026-01-10T11:58:23 (UTC). The WXT position of the source is R.A. = 199.406 deg, DEC = 65.845 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically. Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 199.4371 deg, DEC = 65.8476 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/43363. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41454] GRB 260109C: LCO optical upper limits
by GCN Circulars 09 Jan '26

09 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43362 SUBJECT: GRB 260109C: LCO optical upper limits DATE: 26/01/09 21:27:52 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> D. Turpin, (CEA/Irfu) C. Wu, X.-H. Han, L.-P. Xin (NAOC), A. Saccardi, J. T. Palmerio (CEA/Irfu) report on behalf of the SVOM mission team: We observed the field of the possible GRB 260109C detected by Swift/BAT (Parsotan et al., GCN 43359) with the LCO 1m telescope at the Siding Spring Observatory (SSO) equipped with the Sinistro instrument. Our observation started at 2026-01-09 13:16:04 about 29 minutes after the Swift/BAT trigger time. We obtained 2 epochs of 3x200s exposures in the PanSTARRS z filters. No any uncatalogued source was identified in our stacked frames in agreement with the non detection of the Kilonova-Catcher group in the Rc band (Freeberg et al., GCN 43360). When stacking the our two series of observations, we measure the following upper limits (5 sigma) calibrated against the SkyMapper DR4 catalog, and not corrected for Galactic extinction: z = 19.6 (AB) T_mid - T0 = 40 min This project is funded by the SVOM collaboration. The transient detection and photometric calibration were performed with the STDPipe pipeline (Karpov et al., 2022). View this GCN Circular online at https://gcn.nasa.gov/circulars/43362. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41453] GRB 260109C: Kilonova-Catcher optical upper limit
by GCN Circulars 09 Jan '26

09 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43361 SUBJECT: GRB 260109C: Kilonova-Catcher optical upper limit DATE: 26/01/09 21:03:55 GMT FROM: Damien Turpin at CEA-Saclay <dturpin-astro(a)hotmail.com> M. Freeberg (KNC), D. Turpin (CEA-Saclay/Irfu), C. Andrade(UMN), S. Antier (OCA/IJCLab), M. Coughlin (UMN), S. Karpov (FZU), P. Hello (IJCLAB), M. Pillas (IAP) on behalf of the GRANDMA/Kilonova-Catcher collaboration: We observed the field of GRB 260109C detected by Swift/BAT (Parsotan et al., GCN 43359) with the GRANDMA citizen science project Kilonova-catcher (KNC). Our observations were performed with the iT30 itelescope located at the Siding Spring Observatory and operated by M. Freeberg. Our observations started at TGRB+34.5 min and were taken with Rc filter. In our stacked frames, subtracted from the SkyMapper DR4 template image, we do not detect any optical counterpart in the Swift/BAT error radius. We report our follow-up results in the table below: +---------------+----------+-----------+----------------+-------------+ | Tmid-TGRB (hr)| Exp (s) | Filter | Magnitude | Instrument | +===============+==========+===========+================+=============+ | 0.83 | 6 x 300s | Rc (Vega) | 20.8 (5 sigma) | iT30 | +---------------+----------+-----------+----------------+-------------+ All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained with the Johnson-Cousins filters were calibrated using the GAIA DR3 Synphot catalog. We use the SkyPortal application (skyportal.io) to monitor our observational campaign (Coughlin et al. 2023). GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/) View this GCN Circular online at https://gcn.nasa.gov/circulars/43361. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41452] EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
by GCN Circulars 09 Jan '26

09 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43360 SUBJECT: EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection DATE: 26/01/09 17:32:30 GMT FROM: mariaedvige.ravasio(a)ru.nl M. E. Ravasio (ICE-CSIC and Radboud Univ.), and P.G. Jonker (Radboud Univ.) and E. Burns (LSU), M. Hui (NASA MSFC), R. Hamburg and O. Mukherjee (USRA) report on behalf of the Fermi-GBM Team: Fermi-GBM had full spatial and temporal coverage of the transient EP260105b detected by EP-WXT (Yang et al., GCN 43340, EP Team GCN 43349). There was no Fermi-GBM onboard trigger around the EP trigger time at T0=2026-01-05T18:47:36 UTC. The GBM Targeted Search [1], the most sensitive, coherent search for GRB-like signals, was run in the time interval [-50;+500] s from the EP T0. A transient was found, with the most significant signal at T0-32 s on a 16 s timescale, with a false alarm rate of 6.5e-05 Hz. The localisation is consistent with the EP one, with a spatial association probability of 96.3%. Among the three spectral templates tested, the transient was best-fit with a “normal” spectral template (Band function with Epeak = 230 keV, alpha = -1.0, beta = -2.3) for a GRB. [1] Goldstein et al. 2019 arXiv:1903.12597 View this GCN Circular online at https://gcn.nasa.gov/circulars/43360. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41451] Swift Trigger 1434591: possible GRB 260109C
by GCN Circulars 09 Jan '26

09 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43359 SUBJECT: Swift Trigger 1434591: possible GRB 260109C DATE: 26/01/09 13:17:07 GMT FROM: P.A. Evans at U. Leicester <pae9(a)leicester.ac.uk> T. M. Parsotan (GSFC), P. A. Evans (U Leicester), R. Gupta (NASA GSFC), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), A. Mei (INAF-OAB), K. L. Page (U Leicester), C. Salvaggio (INAF-OAB) and B. Sbarufatti (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team: At 12:47:15 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 260109C (trigger=1434591). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 123.728, -35.258 which is RA(J2000) = 08h 14m 55s Dec(J2000) = -35d 15' 27" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 15 sec. The peak count rate was ~4000 counts/sec (15-350 keV), at ~10 sec after the trigger. The XRT began observing the field at 12:48:41.8 UT, 86.8 seconds after the BAT trigger. No source was detected in 1.3 ks of promptly downlinked data. We are waiting for the full dataset to detect and localise the XRT counterpart. UVOT took a finding chart exposure of 250 seconds with the U filter starting 146 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 25% of the BAT error circle. The typical 3-sigma upper limit has been about 19.2 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the BAT error circle. The limiting magnitude for the list of sources is expected to be about 17.7. No correction has been made for extinction. Burst Advocate for this burst is T. M. Parsotan (tyler.parsotan AT nasa.gov) 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/43359. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41450] GRB 260109B: Fermi GBM Final Real-time Localization
by GCN Circulars 09 Jan '26

09 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43358 SUBJECT: GRB 260109B: Fermi GBM Final Real-time Localization DATE: 26/01/09 08:52:04 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 LONG GRB At 08:41:22 UT on 9 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260109B (trigger 789640887.356258 / 260109362). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 197.5, Dec = -73.9 (J2000 degrees, equivalent to J2000 13h 09m, -73d 54'), with a statistical uncertainty of 13.7 degrees. The angle from the Fermi LAT boresight is 54.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260109362/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260109362/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260109362/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43358. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41449] GRB 260102A: Swift-XRT afterglow detection
by GCN Circulars 09 Jan '26

09 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43357 SUBJECT: GRB 260102A: Swift-XRT afterglow detection DATE: 26/01/09 06:45:08 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> M.G. Bernardini (INAF-OAB), S. Dichiara (PSU), J.A. Kennea (PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-OAR) 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 260102A. The observations now extend from T0+9.6 ks to T0+582.4 ks and have a total exposure time of 7.3 ks. The source previously reported, "Source 2", is fading with >3-sigma significance, and is therefore likely the GRB afterglow. Using 838 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 = 183.94925, +48.25058 which is equivalent to: RA (J2000): 12h 15m 47.82s Dec(J2000): +48d 15' 02.1" with an uncertainty of 6.2 arcsec (radius, 90% confidence). This position is 2.8 arcmin from the SVOM/ECLAIRs position. The source is fading with alpha >0.2. The results of the XRT-team automatic analysis of the likely afterglow are at https://www.swift.ac.uk/ToO_GRBs/00021896/Source2.php. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021896. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43357. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41448] GRB 260109A: Fermi GBM Final Real-time Localization
by GCN Circulars 09 Jan '26

09 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43356 SUBJECT: GRB 260109A: Fermi GBM Final Real-time Localization DATE: 26/01/09 03:55:04 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 LONG GRB At 03:44:24 UT on 9 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260109A (trigger 789623069.789512 / 260109156). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 307.3, Dec = -69.0 (J2000 degrees, equivalent to J2000 20h 29m, -69d 00'), with a statistical uncertainty of 8.0 degrees. The angle from the Fermi LAT boresight is 90.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260109156/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260109156/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260109156/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43356. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41447] GRB 260104A: Swift-BAT refined analysis
by GCN Circulars 09 Jan '26

09 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43355 SUBJECT: GRB 260104A: Swift-BAT refined analysis DATE: 26/01/09 03:01:10 GMT FROM: Tyler Parsotan at NASA GSFC <tyler.parsotan(a)nasa.gov> M. J. Moss (GSFC), S. D. Barthelmy (GSFC), R. Caputo (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 260104A (trigger #1430212) (Caputo, et al., GCN Circ. 43315). The BAT ground-calculated position is RA, Dec = 337.395, -21.291 deg which is RA(J2000) = 22h 29m 34.8s Dec(J2000) = -21d 17' 27.5" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 99%. The mask-weighted light curve shows two pulses. T90 (15-350 keV) is 13.26 +- 2.65 sec (estimated error including systematics). The time-averaged spectrum from T-10.09 to T+5.22 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.32 +- 1.08, and Epeak of 42.5 +- 8.8 keV (chi squared 67.04 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 3.5 +- 0.5 x 10^-07 erg/cm2 and the 1-sec peak flux measured from T-0.23 sec in the 15-150 keV band is 1.3 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.85 +- 0.16 (chi squared 76.81 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/1430212 View this GCN Circular online at https://gcn.nasa.gov/circulars/43355. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41446] GRB 260101A: Swift-BAT refined analysis
by GCN Circulars 09 Jan '26

09 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43354 SUBJECT: GRB 260101A: Swift-BAT refined analysis DATE: 26/01/09 03:00:04 GMT FROM: Tyler Parsotan at NASA GSFC <tyler.parsotan(a)nasa.gov> C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), S. B. Cenko (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+1066 sec from the recent telemetry downlink, we report further analysis of BAT GRB 260101A (trigger #1429608) (Cenko, et al., GCN Circ. 43285). The BAT ground-calculated position is RA, Dec = 86.442, 63.583 deg which is RA(J2000) = 05h 45m 46.2s Dec(J2000) = +63d 34' 57.2" with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 78%. The mask-weighted light curve shows a complex light curve with many emission episodes. T90 (15-350 keV) is 48.00 +- 16.00 sec (estimated error including systematics). The time-averaged spectrum from T-31.26 to T+64.74 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.28 +- 0.23, and Epeak of 109.2 +- 64.4 keV (chi squared 55.17 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 4.5 +- 0.2 x 10^-06 erg/cm2 and the 1-sec peak flux measured from T+24.24 sec in the 15-150 keV band is 4.6 +- 0.3 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.62 +- 0.06 (chi squared 62.07 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/1429608 View this GCN Circular online at https://gcn.nasa.gov/circulars/43354. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41445] Swift GRB 251230A: Global MASTER-Net OT detection
by GCN Circulars 08 Jan '26

08 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43353 SUBJECT: Swift GRB 251230A: Global MASTER-Net OT detection DATE: 26/01/08 18:03:52 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> D. Buckley (South African Astronomical Observatory), V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko, G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), O.A. Gress, N.M. Budnev, O.Ershova (Irkutsk State University, API), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich (Blagoveschensk Educational State University) MASTER-SAAO robotic telescope [1] located in South Africa (South African Astronomical Observatory) was pointed to the GRB 251230A ( S. Lanava et al., GCN 43252) 1908 sec after notice time and 1930 sec after trigger time at 2025-12-30 01:53:52 UT. On our first (180s exposure) set we found 1 optical transient within Swift error-box (ra=179.892 dec=11.415 r=0.05) brighter than 19.2. T-Tmid Date Time Expt. Ra Dec Mag ---------|---------------------|-------|-----------------|-----------------|------- 2020 2025-12-30 01:53:52 180 (11h 59m 35.40s , +11d 26m 18.8s) 16.4 The 5-sigma upper limit has been about 19.2mag 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/43353. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41444] Fermi GRB 260107A: Global MASTER-Net observations report
by GCN Circulars 08 Jan '26

08 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43352 SUBJECT: Fermi GRB 260107A: Global MASTER-Net observations report DATE: 26/01/08 15:38:08 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 Fermi GRB 260107A ( Fermi GBM team, GCN 43350) errorbox 45 sec after notice time and 53 sec after trigger time at 2026-01-07 19:57:55 UT, with upper limit up to 16.7 mag. The observations began at zenith distance = 87 deg. The sun altitude is -22.6 deg. The galactic latitude b = -47 deg., longitude l = 70 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3098086 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 59 | 2026-01-07 19:57:55 | MASTER-SAAO | (22h 46m 37.28s , +02d 30m 33.7s) | C | 10 | 16.1 | 93 | 2026-01-07 19:58:24 | MASTER-SAAO | (22h 46m 36.17s , +02d 30m 45.9s) | C | 20 | 16.4 | 131 | 2026-01-07 19:59:03 | MASTER-SAAO | (22h 46m 35.02s , +02d 30m 58.5s) | C | 20 | 16.3 | 196 | 2026-01-07 19:59:57 | MASTER-SAAO | (22h 44m 44.92s , +00d 59m 56.2s) | C | 40 | 16.7 | 260 | 2026-01-07 20:00:56 | MASTER-SAAO | (22h 44m 43.40s , +01d 00m 12.6s) | C | 50 | 16.3 | 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/43352. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41443] GRB 260102A: AbAO optical observations
by GCN Circulars 08 Jan '26

08 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43351 SUBJECT: GRB 260102A: AbAO optical observations DATE: 26/01/08 14:28:34 GMT FROM: Nicolai Pankov at IKI <colinsergesen(a)gmail.com> N. Pankov (IKI), A. Pozanenko (IKI), R. Ya. Inasaridze (AbAO), A. Volnova (IKI) report on behalf of IKI-GRB-FuN: We performed optical observations of the field of GRB 260102A (XIE et. al, GCN 43295; Evans, GCN 43298; Bernardini et. al, GCN 43304; Yin et. al, GCN 43307; Hamburg, GCN 43308) in the R-filter with the 0.7-meter AS-32 telescope of Abastumani Observatory (AbAO). Two epochs of observations were taken, the first one began on 2026-01-02 19:21:22 UT, i.e. ~0.65 days since trigger. The optical counterpart (Wu et. al, GCN 43300) was not detected in the co-add images of both epochs. The preliminary upper limits and the observation details are given below: Date UT start t-T0 Exp. Filter OT Err. UL (mid, days) (s) (3sigma) 2026-01-02 19:21:22 0.65786 72*60 R n/d n/d 20.1 2026-01-03 19:22:18 1.65850 72*60 R n/d n/d 19.8 The photometry was calibrated using nearby stars from USNO-B1.0 and was not corrected for the Galactic extinction. The obtained results do not contradict the optical upper limits from other groups (Antier et. al, GCN 43303; Saccardi et. al, GCN 43305). View this GCN Circular online at https://gcn.nasa.gov/circulars/43351. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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