GRB 260101A
GCN Circular 43297
Subject
GRB 260101A: Fermi GBM Observation
Date
2026-01-02T05:59:57Z (16 hours ago)
From
Glowbug DEV <boyan.a.hristov@nasa.gov>
Via
Web form
B. Hristov (UAH) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 00:56:30.65 UT on 01 January 2026, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 260101A (trigger 788921795/260101039).
which was also detected by Swift (S. B. Cenko et al. 2026, GCN 43285), SVOM/GRM
(Z. Yu et al. 2026, GCN 43292) and GECAM-B (C. Wang et al. 2026, GCN 43294).
The Fermi GBM on-ground location is consistent with the one reported by Swift.
The angle from the Fermi LAT boresight is 43 degrees.
The GBM light curve consists of multiple emission episodes with a duration (T90)
of about 27.4 s (50-300 keV). The time-averaged spectrum
from T0 to T0+29.6 s s is best fit by
a power law function with an exponential
high-energy cutoff. The power law index is -1.09 +/- 0.01 and
the cutoff energy, parameterized as Epeak, is 143.5 +/- 1.5 keV.
The event fluence (10-1000 keV) in this time interval is
(6.7 +/- 0.12)e-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+25 s in the 10-1000 keV band is 9.6 +/- 0.3 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
sftp://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/"
GCN Circular 43294
Subject
GRB 260101A: GECAM-B detection
Date
2026-01-02T04:42:19Z (17 hours ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
Chen-Wei Wang, Zheng-Hang Yu, Shao-Lin Xiong (IHEP) report on behalf of GECAM team:
GECAM-B was triggered in-flight by GRB 260101A at 2026-01-01T00:56:34.100 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #43284), Swift (S. B. Cenko et al., GCN #43285), SVOM/GRM (Yu et al., GCN #43292).
According to the GECAM-B light curve in about 70-6000 keV, this burst mainly consists of multi-pulses with a duration (T90) of 30.0 +6.0/-3.0 s.
The GECAM-B light curve can be found here:
https://www.bursthub.cn//admin/static/gecambgrb260101A.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).
GCN Circular 43293
Subject
GRB 260101A: NOT spectroscopic observations
Date
2026-01-01T21:05:21Z (a day ago)
From
Andrea Saccardi at CEA/Irfu <andrea.saccardi@cea.fr>
Via
Web form
A. Saccardi (CEA/Irfu), L. Izzo (INAF/OACN and DARK/NBI), A. Martin-Carrillo (UCD), G. Corcoran (UCD), D. B. Malesani (DAWN/NBI and Radboud), K. Valeckas (NOT & NBI), report on behalf of a larger collaboration:
We observed the optical afterglow (Cenko et al., GCN 43285; Perez-Fournon et al., GCN 43286; de Ugarte Postigo et al., GCN 43287) of GRB 260101A detected by Fermi (Fermi GBM team, GCN 43284), Swift (Cenko et al., GCN 43285) and SVOM/GRM (Yu et al., GCN 43292) with the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. A spectrum using grism #4 was secured starting on 2026 Jan 1 at 01:43:54 UT (47 min after the GRB trigger).
Due to bad weather and seeing, we only got two spectra, one of which had a very short exposure time, resulting in a relatively low S/N for the stacked spectrum. The total exposure time is ~ 1500 s covering the wavelength range 3800-9300 AA.
From the unfiltered acquisition 30 s image we measure an AB magnitude of 17.30 +/- 0.07, at a mid-time of 45 minutes after the trigger. Our photometry was calibrated against nearby stars from the r-band PanSTARRS catalogue and not corrected for Galactic extinction.
In a preliminary reduction of the stacked spectrum, we detect a trace over the whole observed wavelength range. At the redshift of z = 2.623 reported by de Ugarte Postigo et al. (GCN 43287) we identify different absorption features, which we interpret as due to Si IV, C IV, and Al II. We note that we do not see a clear absorption corresponding to the weak Ly-alpha.
Further analysis is ongoing.
GCN Circular 43292
Subject
GRB 260101A: SVOM/GRM observation
Date
2026-01-01T14:35:47Z (a day ago)
From
yzh807926@163.com
Via
Web form
SVOM/GRM team: Zheng-Hang Yu, Chen-Wei Wang, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Hui Yang (IRAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by a burst GRB 260101A (SVOM trigger reference: sb26010101) at 2026-01-01T00:56:37.000 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #43284) and Swift (S. B. Cenko et al., GCN #43285).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a precursor followed by a main episode with multiple peaks a T90 of 33.0 +5.5/-3.0 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb260101A.png
In addition, the position of this burst, as determined by Swift/XRT (RA= 89.43, DEC= 63.59 GCN#43285), is located at about 53 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view.
With this localization, the time-averaged spectrum from T0-9 to T0+26 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.39 +/-0.11 and the cutoff energy, parameterized as Epeak, is 150 +48/-27 keV. The event fluence (10-1000 keV) in this time interval is (8.10 +0.83/-0.66)E-06 erg/cm^2.
The 1s peak spectrum, measured from T0+18.5 to T0+19.5 s, if fitted by a power law function with an exponential high-energy cutoff, the power law index is -0.89 +0.15/-0.16 and the cutoff energy, parameterized as Epeak, is 109 +14/-10 keV. The flux (10-1000 keV) in this time interval is (8.99 +0.63/-0.56)E-07 erg/cm^2/s.
With the redshift z = 2.623 by GTC (A. de Ugarte Postigo et al., GCN#43287), GRB 260101A is more consistent with Type II GRBs in the 'Amati' relation diagram, as shown at:https://www.bursthub.cn//admin/static/svgrb260101A_amati.png
And the localization in the 'Yonetoku' relation diagram is shown at:
https://www.bursthub.cn//admin/static/svgrb260101A_yonetoku.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 point of contact for this burst is: Zheng-Hang Yu(IHEP)(zhyu@ihep.ac.cn)
GCN Circular 43291
Subject
GRB 260101A: Swift-XRT refined Analysis
Date
2026-01-01T12:11:45Z (a day ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), S. Lanava (PSU), S.
Dichiara (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L.
Page (U. Leicester), A.P. Beardmore (U. Leicester), E. Ambrosi
(INAF-IASFPA) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 6.7 ks of XRT data for GRB 260101A, from 100 s to 28.9
ks after the trigger. The data comprise 165 s in Windowed Timing (WT)
mode (the first 10 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode.
The late-time light curve (from T0+5.3 ks) can be modelled with a
power-law decay with a decay index of alpha=1.65 (+/-0.17).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.02 (+0.16, -0.15). The
best-fitting absorption column is 2.1 (+/-0.5) x 10^21 cm^-2,
consistent with the Galactic value of 1.6 x 10^21 cm^-2 (Willingale et
al. 2013). The PC mode spectrum has a photon index of 1.91 (+0.16,
-0.15) and a best-fitting absorption column of 2.2 (+0.6, -0.5) x 10^21
cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 3.8 x 10^-11 (5.1 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2.2 (+0.6, -0.5) x 10^21 cm^-2
Galactic foreground: 1.6 x 10^21 cm^-2
Excess significance: 1.8 sigma
Photon index: 1.91 (+0.16, -0.15)
If the light curve continues to decay with a power-law decay index of
1.65, the count rate at T+24 hours will be 3.9 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.5 x
10^-13 (2.0 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
https://www.swift.ac.uk/xrt_products/01429608.
This circular is an official product of the Swift-XRT team.
GCN Circular 43290
Subject
Swift GRB 260101A: Global MASTER-Net observations report
Date
2026-01-01T10:38:30Z (a day ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
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 260101A ( S. B. Cenko et al., GCN 43285) errorbox 34465 sec after notice time and 34491 sec after trigger time at 2026-01-01 10:31:22 UT, with upper limit up to 17.4 mag. Observations started at twilight. The observations began at zenith distance = 44 deg. The sun altitude is -11.9 deg.
The galactic latitude b = 18 deg., longitude l = 150 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3092325
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
34522 | MASTER-Tunka | C | 60 | 17.3 | Coadd
34522 | MASTER-Tunka | C | 60 | 17.4 |
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
GCN Circular 43289
Subject
GRB 260101A: Enhanced Swift-XRT position
Date
2026-01-01T07:52:37Z (2 days ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1689 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 260101A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 86.42902, +63.59238 which is equivalent
to:
RA (J2000): 05h 45m 42.96s
Dec (J2000): +63d 35' 32.6"
with an uncertainty of 2.4 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at https://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the
Swift-XRT team.
GCN Circular 43287
Subject
GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
Date
2026-01-01T03:32:50Z (2 days ago)
From
Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo@gmail.com>
Via
email
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).
GCN Circular 43286
Subject
GRB 260101A: LCO detection of the optical counterpart
Date
2026-01-01T03:09:05Z (2 days ago)
From
Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf@iac.es>
Via
Web form
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).
GCN Circular 43285
Subject
GRB 260101A: Swift detection of a burst with an optical counterpart
Date
2026-01-01T01:13:39Z (2 days ago)
From
K.L. Page at U Leicester <klp5@leicester.ac.uk>
Via
email
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/)
GCN Circular 43284
Subject
GRB 260101A: Fermi GBM Final Real-time Localization
Date
2026-01-01T01:07:07Z (2 days ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
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/quicklook/glg_skymap_all_bn260101039.png
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/quicklook/glg_healpix_all_bn260101039.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260101039/quicklook/glg_lc_medres34_bn260101039.gif