January 2026 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 41379] EP260101a: Einstein Probe detection of an X-ray transient
by GCN Circulars 01 Jan '26

01 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43288 SUBJECT: EP260101a: Einstein Probe detection of an X-ray transient DATE: 26/01/01 07:02:51 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> M.-H. Zhang, Y.-L. Wang, W. Chen, H. Sun (NAO, 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 EP260101a. The transient triggered EP-WXT (ID: 01709250882) at 2026-01-01T06:35:42 (UTC). The WXT position of the source is R.A. = 46.057 deg, DEC = 39.410 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. = 46.0605 deg, DEC = 39.4380 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. Happy 2026!!! 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/43288. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41378] GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
by GCN Circulars 01 Jan '26

01 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43287 SUBJECT: GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst DATE: 26/01/01 03:32:50 GMT FROM: Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo(a)gmail.com> A. de Ugarte Postigo (LAM), A. Martin-Carrillo (UCD), C. C. Thoene (AbAO), D. B. Malesani (DAWN/NBI and Radboud), J. F. Agui Fernandez (CAHA), M. A. Aloy (UV), J. P. U. Fynbo (DAWN/NBI), L. Galbany (IEEC-CSIC), S. Geier (GTC), L. Izzo (INAF/OACN and DARK/NBI), G. Lombardi (GTC), N. A. Rakotondrainibe (LAM), B. Schneider (LAM), N. R. Tanvir (Univ. Leicester), R. Scarpa (GTC) report: We observed the optical counterpart of the new year burst GRB 260101A (Fermi GBM team, GCN 43284, Cenko et al. GCN ) using the Gran Telescopio Canarias (GTC) equipped with the OSIRIS+ instrument. In the r-band 30-s acquisition image (beginning on 2026-01-01 at 02:13:40.010 UT, that is 1.286 hr after trigger), the optical afterglow is well detected with a magnitude 18.05 ± 0.10 (AB), calibrated against nearby SDSS objects, and not corrected for Galactic extinction. A total of 2 spectra of 900 s were secured under poor conditions before clouds came in. Indeed, the second spectrum is already affected by a very high background. The first spectrum started on 2026-01-01 at 02:21:06.010 UT (1.410 hr after trigger), using grism R1000B. Continuum is visible over the range 3600-7800 AA. A number of absorption features are detected, which we interpret as due to Ly-alpha, SiII, OI, CII, SiIV, CIV, FeII and AlII, all at a common redshift z = 2.623, which we suggest to be the redshift of GRB 260101A. We note that the Ly-alpha absorption is very weak, making it a rather peculiar sight line. Happy 2026!!! This work has used the GRBspec database at http://grbspec.eu (de Ugarte Postigo et al. 2014, doi:10.1117/12.2055774). View this GCN Circular online at https://gcn.nasa.gov/circulars/43287. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41377] GRB 260101A: LCO detection of the optical counterpart
by GCN Circulars 01 Jan '26

01 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43286 SUBJECT: GRB 260101A: LCO detection of the optical counterpart DATE: 26/01/01 03:09:05 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf(a)iac.es> I. Pérez-Fournon (IAC and ULL), F. Poidevin (IAC and ULL), D. Cano-Morales, A.E. Hernández-Díaz, I. Correa-Plasencia, E. Lekaroz-Urriza, M. Quintana-Ansaldo (all ULL), and A. López-Oramas (IAC and ULL) Following the detection of the long GRB 260101A, detected by Fermi (Fermi GBM team, GCN #43284) and Swift (Cenko et al., GCN #43285), we observed the field with one of the two Las Cumbres Observatory (LCO) 1-m telescopes, equipped with Sinistro cameras, located at the LCO node at McDonald Observatory, Texas. The observation, a single exposure of 180 sec in the SDSS r' filter, started on 2026-01-01 at 01:55:13 UT, about 58.7 minutes after the Fermi and Swift triggers. The optical counterpart detected by Swift UVOT (Cenko et al., GCN #43285), is clearly detected in our image with a magnitude of r' = 17.67 +/- 0.04, calibrated against PanSTARRS-1 DR2 stars and not corrected for Galactic extinction. This work makes use of observations from the Las Cumbres Observatory global telescope network (LCO program IAC2025B-008, SGLF and Superluminous Supernovae surveys). This work made use of the Astro-COLIBRI platform (P. Reichherzer et al. 2021, ApJS, 256, 5). View this GCN Circular online at https://gcn.nasa.gov/circulars/43286. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41376] GRB 260101A: Swift detection of a burst with an optical counterpart
by GCN Circulars 01 Jan '26

01 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43285 SUBJECT: GRB 260101A: Swift detection of a burst with an optical counterpart DATE: 26/01/01 01:13:39 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> S. B. Cenko (GSFC), J. J. DeLaunay (PSU), S. Dichiara (PSU), R. Gupta (NASA GSFC), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (U Tampa), K. L. Page (U Leicester) and T. M. Parsotan (GSFC) report on behalf of the Neil Gehrels Swift Observatory Team: At 00:56:30 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 260101A (trigger=1429608). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 86.465, +63.568 which is RA(J2000) = 05h 45m 51s Dec(J2000) = +63d 34' 06" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 40 sec. The peak count rate was ~7000 counts/sec (15-350 keV), at ~25 sec after the trigger. The XRT began observing the field at 00:57:54.9 UT, 84.7 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 86.42741, 63.59172 which is equivalent to: RA(J2000) = 05h 45m 42.58s Dec(J2000) = +63d 35' 30.2" with an uncertainty of 3.5 arcseconds (radius, 90% containment). This location is 104 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (1.60 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 3.3 (+3.30/-2.79) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 250 seconds with the U filter starting 144 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 05:45:42.94 = 86.42890 DEC(J2000) = +63:35:32.1 = 63.59225 with a 90%-confidence error radius of about 0.61 arc sec. This position is 4.5 arc sec. from the center of the XRT error circle. The estimated magnitude is 16.03 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.179. Burst Advocate for this burst is S. B. Cenko (brad.cenko 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/43285. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41375] GRB 260101A: Fermi GBM Final Real-time Localization
by GCN Circulars 01 Jan '26

01 Jan '26

TITLE: GCN CIRCULAR NUMBER: 43284 SUBJECT: GRB 260101A: Fermi GBM Final Real-time Localization DATE: 26/01/01 01:07:07 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 00:56:30 UT on 1 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260101A (trigger 788921795.64985 / 260101039). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 83.7, Dec = 64.0 (J2000 degrees, equivalent to J2000 05h 34m, 64d 00'), with a statistical uncertainty of 3.6 degrees. The angle from the Fermi LAT boresight is 43.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260101039/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260101039/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260101039/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43284. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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