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[vsnet-grb-info 41670] GRB 260128B: LCO optical upper limits
by GCN Circulars 30 Jan '26

30 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43567 SUBJECT: GRB 260128B: LCO optical upper limits DATE: 26/01/30 09:25:29 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> C. Wu (NAOC), J. X. Cao (GXU), A. Saccardi (CEA/Irfu), D. Turpin (CEA/Irfu), report on behalf of the SVOM mission team: We observed the field of the SVOM GRB 260128B (Brunet et al., GCN 43561) with the LCO 1m telescope at Cerro Tololo Interamerican Observatory equipped with the Sinistro instrument. Our observation started on 2026-01-30 at 00:48:11 UT (about 1.75 days after the trigger) and we obtained 6x300 s exposures in the SDSS r and 5x300 s exposures in the Pan-STARRS z filters. In the stacked image, we do not detect any new source within the SVOM/ECLAIRs error box, in agreement with Méndez et al. (GCN 43566). We measure the following upper limit calibrated against the PanSTARSS DR1 catalog, and not corrected for Galactic extinction: r > 22.4 AB (3-sigma, mid-time 42.5 hr after the trigger) z > 21.3 AB (3-sigma, mid-time 42.2 hr after the trigger). This project is funded by the SVOM collaboration. View this GCN Circular online at https://gcn.nasa.gov/circulars/43567. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41669] GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
by GCN Circulars 29 Jan '26

29 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43566 SUBJECT: GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits DATE: 26/01/30 05:14:51 GMT FROM: enriquemm(a)astro.unam.mx Enrique Moreno Méndez (UNAM), Jean-Luc Atteia (IRAP), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), 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), N. A. Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), Antonio de Ugarte Postigo (LAM), and Sébastien Le Stum (APC) report: We imaged the field of the SVOM GRB 260128A (Brunet et al., GCN Circ. 43561) using the DDRAGO two-channel wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2026-01-30 02:15 to 03:38 UTC (from 43.5 to 44.8 hours after the trigger) and obtained 60 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. WIthin the ECLAIRs 12 arcmin error circle (Brunet et al., GCN Circ. 43561), and in comparison to the corresponding PS1 images, we do not detect any new sources to preliminary 5-sigma limiting magnitudes of r > 22.3 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/43566. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41668] GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
by GCN Circulars 29 Jan '26

29 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43566 SUBJECT: GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits DATE: 26/01/30 05:14:51 GMT FROM: enriquemm(a)astro.unam.mx Enrique Moreno Méndez (UNAM), Jean-Luc Atteia (IRAP), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), 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), N. A. Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), Antonio de Ugarte Postigo (LAM), and Sébastien Le Stum (APC) report: We imaged the field of the SVOM GRB 260128A (Brunet et al., GCN Circ. 43561) using the DDRAGO two-channel wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2026-01-30 02:15 to 03:38 UTC (from 43.5 to 44.8 hours after the trigger) and obtained 60 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. WIthin the ECLAIRs 12 arcmin error circle (Brunet et al., GCN Circ. 43561), and in comparison to the corresponding PS1 images, we do not detect any new sources to preliminary 5-sigma limiting magnitudes of r > 22.3 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/43566. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41667] EP260128a: J band upper limit by SYSU 80cm infrared telescope
by GCN Circulars 29 Jan '26

29 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43565 SUBJECT: EP260128a: J band upper limit by SYSU 80cm infrared telescope DATE: 26/01/30 04:42:48 GMT FROM: linp(a)mail2.sysu.edu.cn Pu Lin, Jin-Ji Li, Hao-Nan Yang, Zhong-Nan Dong, Yan Yu, Jia-Qi Lin, Wei-Sen Huang, Chun Chen, Duo-Le Cao, P H Thomas Tam, Rong-Feng Shen, Bin Ma (Sun Yat-sen University) report on behalf of the SYSU 80cm infrared telescope team: We observed the field of EP260128a (Zhou et al., GCN 43549) using the Sun Yat-sen University 80cm infrared telescope with 167 x 20 s exposures in J band. The calculated position is RA = 128.32533 deg, DEC = -10.27565 deg J2000, from EP/FXT observation (Zhou et al., GCN 43554). Our observations began at 2026-1-29 20:00:00 UTC, 20.33 hours after the EP trigger. We do not detect any counterpart at the position of the optical afterglow (H. L. Li et al., GCN 43551, J. A. Quirola-Vasquez et al., GCN 43552, R. A. J. Eyles-Ferris et al., GCN 43553, L.B. He et al., GCN 43555), down to a 5-sigma depth of J~ 18.5 Vega magnitudes. The SYSU 80cm infrared telescope is operated and managed by the Department of Astronomy, Sun Yat-sen University. View this GCN Circular online at https://gcn.nasa.gov/circulars/43565. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41666] IPN triangulation of GRB 260121A
by GCN Circulars 29 Jan '26

29 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43564 SUBJECT: IPN triangulation of GRB 260121A DATE: 26/01/29 23:10:15 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the MGNS/BepiColombo team, J. Benkhoff on behalf of the BepiColombo team, D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, A. Goldstein, M. S. Briggs, C. Wilson-Hodge, M. Hui, and E. Burns on behalf of the Fermi GBM team, G. Waratkar, J.Joshi, V. Bhalerao, D. Bhattacharya, A. Arya, and S. Vadawale, on behalf of the Astrosat-CZTI team, E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, A. Tohuvavohu, and J. DeLaunay on behalf of the Swift-BAT team, and D. Kapshtan, M. Orlov, V. Bazunova, E. Shchepin, E. Meltsov, K. Starikov, A. Khogoev, on behalf of the 239Alferov team, report: The long-duration GRB 260121A was detected by Fermi (GBM; in continuous TTE data), Konus-Wind, Astrosat (CZTI), INTEGRAL (SPI-ACS), 239Alferov CubeSat, and BepiColombo-MGNS at about 8552 s UT (02:22:32). We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 213.591 (14h 14m 22s) -62.629 (-62d 37' 45") Corners: 212.178 (14h 08m 43s) -65.088 (-65d 05' 17") 212.129 (14h 08m 31s) -64.984 (-64d 59' 01") 214.879 (14h 19m 31s) -60.111 (-60d 06' 38") 214.922 (14h 19m 41s) -60.220 (-60d 13' 11") --------------------------------------------- The error box area is 855 sq. arcmin, and its maximum dimension is 5.13 deg (the minimum one is 3 arcmin). The Sun distance was 72 deg. The localization may be improved. A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB260121_T08549/IPN/ The HEALPix triangulation map is the multi-order HEALPix in units of probability density. The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular. View this GCN Circular online at https://gcn.nasa.gov/circulars/43564. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41665] GRB 260127A: Swift-BAT refined analysis
by GCN Circulars 29 Jan '26

29 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43563 SUBJECT: GRB 260127A: Swift-BAT refined analysis DATE: 26/01/29 21:16:56 GMT FROM: D. R. Sadaula at NASA GSFC <dev.r.sadaula(a)nasa.gov> T. Parsotan (GSFC), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), 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+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 260127A (trigger #1444088) (Kilingler et al., GCN Circ. 43529). The BAT ground-calculated position is RA, Dec = 231.879, 6.758 deg which is RA(J2000) = 15h 27m 30.9s Dec(J2000) = +06d 45' 28.4" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 40%. The classic pulse has a single peak that started around T+20 sec and has a structure before it at ~T+5 sec. The duration of the burst is ~100 sec. T90 (15-350 keV) is 104.06 +- 19.41 sec (estimated error including systematics). The time-averaged spectrum using multiple GTIs from T-2.68 to T+7.62, T+9.00 to T+84.43 sec, and T+86.00 to T+117.04 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.76 +- 0.15. The fluence in the 15-150 keV band is 2.3 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+33.36 sec in the 15-150 keV band is 2.1 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1444088 View this GCN Circular online at https://gcn.nasa.gov/circulars/43563. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41664] GRB 260129B: Fermi GBM Final Localization
by GCN Circulars 29 Jan '26

29 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43562 SUBJECT: GRB 260129B: Fermi GBM Final Localization DATE: 26/01/29 19:56:51 GMT FROM: Christian Malacaria at INAF-OAR <cmalacaria.astro(a)gmail.com> "The Fermi GBM team reports the detection of a likely Long GRB. At 10:06:57 UT on 29 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260129B (trigger 791374022 / 260129421). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 0.36, Dec = -67.05 (J2000 degrees, equivalent to J2000 00h 01m, -67d 03'), with a statistical uncertainty of 10.6 degrees. The angle from the Fermi LAT boresight is 129.9 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260129421/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260129421/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260129421/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/43562. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41663] GRB 260128B: SVOM detection of a burst through offline search
by GCN Circulars 29 Jan '26

29 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43561 SUBJECT: GRB 260128B: SVOM detection of a burst through offline search DATE: 26/01/29 19:08:31 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> M. Brunet (IRAP), S. Le Stum, A. Coleiro (APC), O. Godet (IRAP),report on behalf of the SVOM team: The SVOM/ECLAIRs telescope detected a transient source, labelled GRB 260128B, starting at 2026-01-28T06:48:34.72 UTC (T0), through an offline search with the event-by-event data downloaded through the X-band ground station. The burst was detected within several energy ranges and timescales. The best detection is obtained by the Image Trigger with a signal-to-noise ratio of 7.5 within 4-20 keV over a time window of 10.24 seconds starting at T0-10.24s. The lightcurve shows a single peaked structure lasting around 4s. The localization of the source is RA, Dec = 27.734, -25.867 degrees: RA (J2000) = 01h50m56.16s Dec (J2000) = -25d52m01.20s with a 90% C.L. radius of 12.0 arcmin (including systematic error of 6 arcmin added in quadrature). We note that no bright catalogued X-ray sources are found in the error box. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. ECLAIRs was developed jointly by APC, CEA, CNES, and IRAP. The SVOM point of contact for this event is : Sébastien Le Stum : lestum at apc.in2p3.fr Please contact him by email if you require additional information regarding the SVOM follow-up of this burst. View this GCN Circular online at https://gcn.nasa.gov/circulars/43561. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41662] GRB 260129A: Fermi GBM Final Localization
by GCN Circulars 29 Jan '26

29 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43560 SUBJECT: GRB 260129A: Fermi GBM Final Localization DATE: 26/01/29 18:53:30 GMT FROM: Christian Malacaria at INAF-OAR <cmalacaria.astro(a)gmail.com> "The Fermi GBM team reports the detection of a likely Long GRB. At 04:33:12 UT on 29 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260129A (trigger 791353997 / 260129190). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 160.4, Dec = -46.8 (J2000 degrees, equivalent to J2000 10h 41m, -46d 48'), with a statistical uncertainty of 9.7 degrees. The angle from the Fermi LAT boresight is 20.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260129190/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260129190/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260129190/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/43560. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41661] IPN triangulation of GRB 260127B (short)
by GCN Circulars 29 Jan '26

29 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43559 SUBJECT: IPN triangulation of GRB 260127B (short) DATE: 26/01/29 18:13:36 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru> A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, and A. Goldstein, M. S. Briggs, C. Wilson-Hodge, and E. Burns on behalf of the Fermi GBM team, report: The short-duration GRB 260127B (Fermi-GBM detection: The Fermi GBM team, GCN 43533) was detected by Fermi (GBM trigger 791236957) and Konus-Wind at about 72153 s UT (20:02:33). We have triangulated it to a Konus-GBM annulus centered at RA(2000)=104.669 deg (06h 58m 40s) Dec(2000)=+21.845 deg (+21d 50' 41"), whose radius is 72.490 +/- 0.104 deg (3 sigma). The annulus combined with the Fermi-GBM final position (GCN 43533; glg_healpix_all_bn260127835_v00) gives ~6.8 sq. deg (3 sigma) localization region. The the optical source detected by GOTO (GOTO26aih/AT2026bnn, GCN 43538) is outside the IPN annulus. A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB260127_T72154/IPN/ View this GCN Circular online at https://gcn.nasa.gov/circulars/43559. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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