GRB 260914A
GCN Circular 45605
Subject
GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
Date
2026-09-17T04:04:09Z (3 hours ago)
From
Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct@iaa.es>
Via
email
A.J. Castro-Tirado (IAA-CSIC), Y.-D. Hu (GXU), I. Perez-Garcia, M.D. Caballero-Garcia, M. Gritsevich, S. Guziy (IAA-CSIC), J. F. Agui Fernandez, M.M. Sanchez Andujar (CAHA), D. Slumstrup and D. Perez-Valladares (IAC, GRANTECAN), on behalf of a larger collaboration, report:
Following the detection of GRB 260914A by SVOM/ECLAIRs (Wang et al. GCN 45562), we triggered the 2.2m CAHA telescope (equipped with CAFOS) in Almeria (Spain). Images in the Sloan g, r, i and z bands were gathered on Sep 14 starting at 22:01 UT (i.e. ~10.85 hours after the trigger).
We still detect the optical afterglow in the gri-bands, confirming the fast decay based in all reports published so far (Akl et al., GCN 45564; Palmerio et al., GCN 45565; Li et al., GCN 45566; Shi et al., GCN 45567, Saccardi et al., GCN 45568, Volnova et al., GCN 45595). On Sep 14, 22:28 UT, we measure i: 21.1 ± 0.1 (on a 600s image coadd).
We also obtained optical spectroscopy at the 10.4m GTC telescope (equipped with OSIRIS+) in La Palma (Spain) on Sep 15, starting at 04:27 UT (i.e. ~17.25 hours after the trigger), covering the range 3800-9500 A. Based on a preliminary analysis, we identify emission lines of [O II] and H-beta, thus confirming the redshift of the underlying star-forming galaxy at z ~0.778, as reported by Saccardi et al. (GCN 45579) and Yan et al. (GCN 45582).
Moreover, in the faint continuum extending to the bluest wavelengths in the R1000B grism (3x750s exposure), we tentatively identify the Mg II doublet in absorption at the redshift of z ~0.778, thus supporting other findings (Yan et al. GCN 45582) and confirming the association between GRB 260914A and the underlying above-mentioned galaxy.
We thank the staff at both CAHA and GTC for their excellent support.
GCN Circular 45596
Subject
GRB 260914A: SVOM/GRM observation
Date
2026-09-16T16:14:48Z (15 hours ago)
From
Jin-Ye Luo <jy_luo2002@163.com>
Via
Web form
SVOM/GRM team: Jin-Ye Luo, Wen-Jun Tan, Chen-Wei Wang, Yue Wang, Chao Zheng, Zheng-Hang Yu, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team:
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by GRB 260914A at 2026-09-14T11:12:33.000 (T0), which is also detected by SVOM/ECLAIRs (Wang et al., GCN #45562; Brunet et al., GCN #45594) and Fermi/GBM (Fermi GBM team, GCN #45569).
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 possible precursor. The burst has a T90 of 3.5 +/-1.0 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn/gcn/2026/svgrb260914A.png
With the localization from SVOM/ECLAIRs (GCN #45564), the time-averaged spectrum from T0-4 to T0+3 s is best fitted by a power-law function with an exponential high-energy cutoff. The power law index is -0.4 +0.7/-0.6 and the cutoff energy, parameterized as Epeak, is 33.3 +4.3/-5.2 keV. The event fluence (10-1000 keV) in this time interval is (6.30 +0.66/−0.63)E-07 erg/cm^2.
The localization of GRB 260914A in the 'Amati' relation diagram is shown at: https://www.bursthub.cn/gcn/2026/svgrb260914A_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: Jin-Ye Luo (IHEP) (luojy@ihep.ac.cn)
GCN Circular 45595
Subject
GRB 260914A: Mondy and TShAO optical observations
Date
2026-09-16T16:00:26Z (15 hours ago)
From
Alina Volnova at IKI RAS <alinusss@gmail.com>
Via
Web form
A. Volnova (IKI), E. Klunko (ISTP), I. Reva (FAI), A. Pozanenko (IKI), A. Moskvitin (SAO RAS), N. Pankov (IKI) report on behalf of IKI-GRB-FuN:
We observed the field of the GRB 260914A detected by SVOM/ECLAIR (Wang et al., GCN 45562) and Fermi/GBM (Hamburg, GCN 45569) at z = 0.778 (Saccardi et al., GCN 45579) with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy), and the Zeiss-1000 1m telescope of the Tien-Shan Observatory (TSHAO) taking several frames in R-band. The observations at Mondy started on Sep. 14 (UT) 14:51:19 (i.e., ~3.5h after the trigger), followed by the observations at TShAO starting on Sep. 14 (UT) 19:06:53 (i.e., ~8h after the trigger).
The optical/NIR counterpart (Akl et al., GCN 45564; Palmerio et al., GCN 45565; Li et al., GCN 45566; Shi et al., GCN 45567; Saccardi et al., GCN 45568; Saccardi et al., GCN 45579; Yang et al., GCN 45582; Brivio et al., GCN 45583) is detected in the stacked frames of both observatories.
The photometry and observational details are the following:
Date UT start t-T0 Exp, Filter Obj Err UL Site/Telescope
(mid,days) (n*s) (3sigma)
2026-09-14 14:51:19 0.17348 18*120 R 21.14 0.08 22.4 Mondy/AZT-33IK
2026-09-14 19:06:53 0.37395 68*90 R 21.29 0.19 22.1 TShAO/Z1000
The preliminary photometry (Vega) is based on nearby PS1 stars (Lupton 2005 transformation) and not corrected for the Galactic extinction.
The photometry of the source is affected by the underlying host galaxy reported by Saccardi et al. (GCN 45579) with Legacy survey magnitudes g=22.91, r=22.08, z=21.39.
GCN Circular 45594
Subject
GRB 260914A: SVOM/ECLAIRs refined analysis
Date
2026-09-16T13:26:51Z (18 hours ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
M. Brunet (IRAP), N. Dagoneau (CEA), O. Godet (IRAP), C. Wang (IHEP), W. Xie (NAOC) report on behalf of the SVOM/ECLAIRs team:
Using the event-by-event data downloaded through the X-band ground station, we report further analysis of SVOM/ECLAIRs observations of GRB 260914A (SVOM burst-id sb26091401 – GCN 45562, trigger time T0 = 2026-09-14T11:12:31 UTC), which was also detected by Fermi/GBM as a sub-threshold (Hamburg, GCN 45569).
The burst that triggered ECLAIRs onboard shows a main broad peak from T0-2.2 s to T0+8.3 s seen below 50 keV and a soft precursor from T0-10.4 s to T0-8.8 s seen below 20 keV. The burst duration estimated through the imaging technique is T90 = 15.5 -7.2/+1.5 s in the 4-120 keV energy band.
The time-averaged spectrum from T0-2.2 s to T0+8.3 s in the 5-120 keV energy range is best fitted by a powerlaw model, with alpha = -1.98 +/-0.07. With this model, the 4-120 keV fluence is (1.68 +/-0.11)e-6 erg/cm^2 and the 4-120 keV photon flux is 7.0 +/-0.3 ph/cm^2/s.
Using a band model with alpha = -1 and beta = -2.5 (fixed) also gives a good fit with Epeak = 14.2 +2.0/-1.8 keV. With this model, the 4-120 keV fluence is (1.43 +/-0.08)e-6 erg/cm^2 and the 4-120 keV photon flux is 6.5 +/-0.3 ph/cm^2/s.
Assuming a redshift of z=0.778 (Saccardi et al., GCN 45579, Yang et al., GCN 45582), a standard cosmology with H_0 = 67.3 km/s/Mpc and Omega_M = 0.315 (Planck Collaboration, 2014) and the previous band model with Epeak = 14.2 keV, we estimate the isotropic energy release E_iso is about 3.6 e51 erg. With these estimates, GRB 260914A appears close to the Ep,z and E_iso ranges distribution of Type II (collapsar-like) GRBs on the Amati relation reported by Willingale et al. 2017.
All the quoted errors are at the 68% confidence level.
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. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC.
The SVOM/ECLAIRs point of contact for this burst is: Nicolas Dagoneau (nicolas.dagoneau at cea.fr)
GCN Circular 45583
Subject
GRB 260914A: REM optical/NIR observations
Date
2026-09-15T12:24:13Z (2 days ago)
From
Riccardo Brivio at INAF-OAB <riccardo.brivio@inaf.it>
Via
Web form
R. Brivio, M. Ferro, F. Guidolin S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team:
We observed the field of GRB 260914A, detected by SVOM/ECLAIRs (Wang et al., GCN 45562) and Fermi/GBM (Hamburg, GCN 45569) with the REM 60 cm robotic telescope located at the ESO observatory of La Silla (Chile).
The observations were carried out in the g, r, i, z, and J bands, started on 2026-09-15 at 04:25:44 UT (i.e. 0.72 d after the burst) and lasted for about 1 hr.
From preliminary photometry, we do not detect the reported optical/NIR counterpart (Akl et al., GCN 45564; Palmerio et al., GCN 45565; Li et al., GCN 45566; Shi et al., GCN 45567; Saccardi et al., GCN 45568; Saccardi et al., GCN 45579; Yang et al., GCN 45582) down to the following 3sigma limits:
r > 20.2 (AB; calibrated against the Pan-STARRS catalogue),
at a mid-time of 0.76 d after the trigger;
J > 14.2 (Vega; calibrated against the 2MASS catalogue),
at a mid-time of 0.72 d after the trigger.
GCN Circular 45582
Subject
GRB 260914A: VLT/X-shooter observations and redshift confirmation
Date
2026-09-15T11:39:05Z (2 days ago)
From
Yu-Han Yang at University of Rome Tor Vergata <yyang@roma2.infn.it>
Via
Web form
Y.-H. Yang, M. Yadav, E. Troja, N. Monsalves (U Rome) report on behalf of the ERC BHianca team:
We observed the field of GRB 260914A (Wang et al., GCN 45562) with the X-shooter spectrograph on the ESO Very Large Telescope (VLT). Observations began at UT 06:03:21 on 2026-09-15 (18.8 hours after the GRB trigger) at an average airmass of ~1.8, and consisted of spectroscopy (4 × 600 s) and imaging with the acquisition and guiding (A&G) camera (360 s in each of the r and z filters).
We placed the 1 arcsec slit center at the position of the optical counterpart (Akl et al., GCN 45564; Palmerio et al., GCN 45565; Li et al., GCN 45566; Shi et al., GCN 45567, Saccardi et al., GCN 45568). Based on a preliminary analysis, we identify the emission lines of H-alpha, H-beta, [O II] and [O III] in the VIS and NIR arms confirming the presence of an underlying star-forming galaxy at z ~0.778, as reported by Saccardi et al. (GCN 45579).
For this galaxy, the chance coincidence probability is Pcc~ 0.3% (Saccardi et al. GCN 45579). However, the burst is located ~10 arcsec from a bright (r~16.5 mag) and nearby (z~0.112) galaxy, LEDA 1860670, with Pcc~0.1% derived using the prescription of Becerra et al. (2023, MNRAS, 522, 5204) which is calibrated down to bright galaxies. Therefore, on probabilistic grounds, the host galaxy’s association remains uncertain.
Finally, we note that the UVB arm shows a weak continuum. As the underlying galaxy has catalogued magnitude g~23.4 AB (Legacy Survey DR10, Dey et al. 2019), the observed trace is likely contributed from the GRB afterglow. Over the faint continuum, we tentatively identify weak Mg II absorptions at a consistent redshift of z ~0.778. If confirmed, this would solidify the association between the GRB and the underlying, distant galaxy.
We thank the staff at the VLT for the rapid execution of these observations.
GCN Circular 45579
Subject
GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
Date
2026-09-15T08:47:39Z (2 days ago)
From
Andrea Saccardi at CEA/Irfu <andrea.saccardi@cea.fr>
Via
Web form
A. Saccardi (CEA/Irfu), M. Garnichey (LUX-Paris Obs.), D. B. Malesani (DAWN/NBI and Radboud), G. Corcoran (UCD), V. D’Elia (ASI/SSDC), M. De Pasquale (U. of Messina), L. Izzo (INAF/OAC), A. L. Thakur (INAF/IAPS), S. D. Vergani (LUX-Paris Obs.), report on behalf of the Stargate collaboration:
We observed the optical counterpart (Akl et al., GCN 45564; Palmerio et al., GCN 45565; Li et
al., GCN 45566; Shi et al., GCN 45567; Saccardi et al., GCN 45568) of the SVOM GRB 260914A (Wang et al., GCN 45562; see also Hamburg, GCN 45569) using the ESO VLT UT3 (Melipal) equipped with the X-shooter spectrograph.
In a 30-s image taken with the acquisition camera (20.189 hr after the SVOM/ECLAIRs trigger), the counterpart is detected with a magnitude r = 22.19 +- 0.12 AB, calibrated against Pan-STARRS and not corrected for Galactic extinction. This is similar to the magnitude r ~ 22.1 of the underlying object seen in the Legacy survey, indicating that the transient is no longer dominating the total emission.
A spectrum covering the wavelength range 3000-21000 AA was secured, with a total exposure time of 4x600 s in each of the UVB, VIS, and NIR arms. Our observation started at 07:33 UT on 2026 September 15, i.e. about 20.34 hr after the SVOM trigger.
From a preliminary analysis, only faint continuum is present, but clear emission lines are detected in the visible and near-infrared arms, which we identify as H-alpha, the [O III] 4959, 5007 doublet, H-beta, and the [O II] 3726, 3729 doublet, all at a common redshift of z = 0.778.
The chance association probability between the underlying archival object at z = 0.778 and the afterglow is around 0.3% (Bloom et al. 2001), indicating that this is the likely host galaxy. We note though the presence of a bright galaxy (LEDA 1860670) some 10" away from the counterpart, with a spectroscopic redshift z = 0.112 from DESI (DESI collaboration et al., doi:10.3847/1538-3881/ae4c43) and a larger, but comparable, chance association probability. As long GRBs have mostly small host offsets, we favor the z = 0.778 interpretation, though we cannot conclusively rule out an association with the low-redshift galaxy.
We acknowledge excellent support from the ESO staff in Paranal.
GCN Circular 45571
Subject
GRB 260914A: EP-FXT follow-up observation
Date
2026-09-15T03:41:14Z (2 days ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
J. Yang (ZZU), W. F. Wen (SZTU), R. C. Chen (NJU), T. Wu (AHNU), Z. X. Ling (NAO, CAS) on behalf of the Einstein Probe (EP) team:
EP-FXT performed a follow-up observation of GRB 260914A, detected by SVOM/ECLAIRs and SVOM/GRM (sb26091401; Wang et al., GCN 45562), which was also observed in optical by SVOM/COLIBRÍ (Akl et al., GCN 45564), SVOM/VT (Palmerio et al., GCN 45565; Li et al., GCN 45566), SVOM/C-GFT (Shi et al., GCN 45567) and LCO (Saccardi et al., GCN 45568). The observation started at 2026-09-14 12:36:30 (UTC), about 1.4 hours after the SVOM/ECLAIRs trigger, with an exposure time of 6 ks.
On-ground analysis of the EP-FXT data found an uncataloged fading X-ray source within the SVOM/ECLAIRs error region (Wang et al., GCN 45562). The preliminary results for the X-ray source are as follows:
Source name: EPF_J020623.5+291518
R.A., Decl. (J2000) = 31.5979, 29.2548 deg
Localization error radius = 10 arcsec
0.5-10 keV flux = 2.7e-12 erg/cm^ 2/s
Flux error = 2.2e-13 erg/cm^2/s (1 sigma)
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).
GCN Circular 45569
Subject
Fermi GBM Sub-Threshold Detection of GRB 260914A
Date
2026-09-15T01:14:15Z (2 days ago)
Edited On
2026-09-15T12:51:59Z (2 days ago)
From
rhamburg@usra.edu
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of rhamburg@usra.edu
Via
Web form
R. Hamburg (USRA) reports on behalf of the Fermi-GBM Team:
SVOM ECLAIRs detected GRB 260914A on 2026-09-14 at 11:12:31 UTC (GCN 45562). There was no Fermi-GBM onboard trigger around this time.
The GBM Targeted Search [1], the most sensitive coherent search for GRB-like signals in GBM, identified a spatially-consistent transient at 2026-09-14T11:12:30.552 UTC. The Targeted Search event is found most significantly on the 4.096 s timescale with a false alarm rate of 6.1e-5 Hz. The Fermi-MET of this transient is 811077155.552 s. Additionally, the Targeted Search event was found with the highest significance using a soft GRB spectrum (Band function with Epeak = 70 keV, alpha = -1.9, beta = -3.7).
[1] Goldstein et al. 2019 arXiv:1903.12597
GCN Circular 45568
Subject
GRB 260914A: LCO optical observation
Date
2026-09-14T20:28:02Z (2 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
A. Saccardi (CEA/Irfu), S. J. Yin (GXU), D. Turpin (CEA/Irfu), D. B. Malesani (DAWN/NBI and Radboud), J. T. Palmerio (CEA/Irfu), K. Liu (GXU), Y. Ma (NAOC), report on behalf of the SVOM mission team:
We observed the field of GRB 260914A detected by SVOM/ECLAIRs (Wang et al., GCN 45562) with the LCO 1m telescope at Siding Spring Observatory equipped with the Sinistro instrument.
Our observation started on 2026-09-14 at 15:01:12 UT (about 3.81 hr after the trigger) and we obtained 3x200 s exposures in each of the SDSS r and Pan-STARRS z filters.
The optical counterpart (Akl et al., GCN 45564; Palmerio et al., GCN 45565; Li et al., GCN 45566; Shi et al., GCN 45567) is detected only in our r-band images. We measure the following magnitudes calibrated against the Pan-STARRS DR1 catalog, and not corrected for Galactic extinction:
r = 20.9 +/- 0.2 AB (mid-time 4.14 hr after the trigger).
Note that the magnitude reported above is not template-subtracted and is contaminated by an underlying object (r ~ 22.1) visible in the Legacy survey, and by the presence of the large nearby galaxy LEDA 1860670 (whose relationship with the GRB is unclear at the moment).
This project is funded by the SVOM collaboration.
GCN Circular 45567
Subject
GRB 260914A: SVOM/C-GFT optical observations
Date
2026-09-14T17:04:40Z (3 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
Y.Y. Shi (GXU),Z. Kang (CHO), C. Wu (NAOC), 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), K. Liu (GXU), Y.N. Ma (NAOC) report on behalf of the SVOM/C-GFT team:
We observed the field of GRB 260914A detected by SVOM/ECLAIRs (Wang et al., GCN 45562) with LATIOS on SVOM/C-GFT. Observations started at 2026-09-14T12:11:29 UTC, ~0.98 hr after the trigger.
The optical candidate (Akl et al., GCN 45564; Palmerio et al., GCN 45565; Li et al., GCN 45566) was faintly detected in our stacked images of band i. The magnitude is:
| [date-obs(mid-time)] | Mid_t-T0(h) | exposure time (s) | band | mag (AB) | mag_err |
|---|---|---|---|---|---|
| 2026-09-14T13:06:45 | 1.9 | 30×90s | i | 20.15 | +/- 0.12 |
The photometry was calibrated against Pan-STARRS1 DR1 catalogue and no correction for Galactic dust extinction was applied.
We thank the observation assistants H.-X. Xue and B.-W. Li 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 arcmin x 21 arcmin 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.
GCN Circular 45566
Subject
GRB 260914A: SVOM/VT optical counterpart confirmation
Date
2026-09-14T15:09:09Z (3 days ago)
From
Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>
Via
Web form
H. L. Li, Y. N. Ma, C. Wu, L. P. Xin, Y. L. Qiu, Z. H. Yao, J. R. Xu, L. S. Chen, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), J. T. Palmerio (CEA/Irfu) report on behalf of the SVOM/VT team.
SVOM/VT performed observations with automatic slew of GRB 260914A detected by SVOM/ECLAIRs (sb26091401, Wang et al., GCN 45562). Our observation started on 2026-09-14T12:04:35 UTC (about 50.5 minutes after the trigger) in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously .
With the VT X-band telemetry data, the optical counterpart (Akl et al., GCN 45564; Palmerio et al., GCN 45565) was detected in both single and stacked images.
The following measurements are in the AB magnitude and are not corrected for Galactic extinction:
Mid time | Band | Exposure Time | Brightness
0.92 hr VT_B 7*50 s 20.48 +/- 0.11 mag
0.93 hr VT_R 5*50 s 20.05 +/- 0.11 mag
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.
GCN Circular 45565
Subject
GRB 260914A: SVOM/VT optical observation from VHF data
Date
2026-09-14T14:22:56Z (3 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
J. T. Palmerio (CEA/Irfu), C. Wu (NAOC), D. Turpin, A. Saccardi (CEA/Irfu), Y. L. Qiu, L. P. Xin (NAOC), K. Liu (GXU), Y. Ma (NAOC), on behalf of the SVOM/VT team.
After the trigger by SVOM/ECLAIRs (sb26091401) at 2026-09-14T11:12:31 UTC (T0), SVOM performed an automatic slew on the burst location (Wang et al., GCN 45562).
From a preliminary analysis of the 1-bit subimage and source list downloaded via VHF network, at least one credible candidate is identified, the details of which are presented below.
VT_ID 608:
The position of this candidate is R.A., Dec. 31.59913, 29.25485 degrees, corresponding to:
R.A. (J2000) = 2h06m23.8s
Dec. (J2000) = 29d15m17.5s
with an uncertainty of 0.50 arcsec.
This location is consistent with the optical afterglow reported by Akl et al. (GCN 45564).
This candidate was detected in both VT_R and VT_Band was flagged as a catalogued source whose brightness faded over the course of the VT observations. The candidate's magnitudes are:
| date-obs (UTC) | mid-time | exposure | VT_B mag(AB) | VT_R mag(AB) |
| -------------------- | ----------- | --------- | ------------- | ------------- |
| 2026-09-14T12:04:35 | 54.55 min | 6*50 sec | - | 19.80 ± 0.04 |
| 2026-09-14T12:51:15 | 100.8 min | 5*50 sec | 20.94 ± 0.10 | 20.02 ± 0.07 |
Magnitudes were not corrected for Galactic reddening.
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/VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.
The Burst Advocate (BA) on shift for this alert is Yinuo Ma: mayn@bao.ac.cn
Please contact the BA by email if you require additional information.
GCN Circular 45564
Subject
GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
Date
2026-09-14T13:58:55Z (3 days ago)
From
J.-G. Ducoin at CPPM <ducoin@cppm.in2p3.fr>
Via
Web form
Dalya Akl (NYUAD), Fredd Sánchez Álvarez (UNAM), Jean-Grégoire Ducoin (CPPM), Noémie Globus (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Leonardo García-García (UNAM), Ramandeep Gill (UNAM), Marion Guelfand (CPPM), Asuka Kuwata (UNAM), Massimiliano Lincetto (CPPM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Benjamin Schneider (LAM), Antonio de Ugarte Postigo (LAM), Alan M. Watson (UNAM) and Damien Turpin (CEA/Irfu) report:
We imaged the field of the SVOM GRB 260914A (Wang et al., GCN Circ. 45562) using the DDRAGO two-channel wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2026-09-14 11:14:09 to 12:03:42 UTC (from 1.4 to 51 minutes after the trigger) and obtained 43 minutes of simultaneous exposure in the r and z filters.
The data were reduced, coadded, and analysed with the COLIBRÍ and ASU pipelines. The photometry was calibrated using nearby stars from the PanSTARRS DR2 catalog, is in the AB system, and is not corrected for Galactic extinction.
In the stacked image, we tentatively detected a source revealed by image subtraction against Pan Starrs and Legacy Survey in both bands, consistent with the SVOM/ECLAIRs error circle at:
RA (J2000) = 02:06:23.78 = 31.5991 deg
Dec (J2000) = +29:15:17.5 = 29.2549 deg
with an estimated astrometric uncertainty of 0.5 arcsec.
The preliminary magnitude derived for that source after subtraction is:
r = 20.14 ± 0.04
z = 19.66 ± 0.04
We encourage additional observations to confirm the nature of the source.
We thank the staff of the Observatorio Astronómico Nacional at Sierra de San Pedro Mártir, as well as the technical and engineering teams at CEA, CPPM, IRAP, LAM, OHP, OSU Pytheas, and UNAM.
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.
GCN Circular 45562
Subject
GRB 260914A: SVOM detection of a burst
Date
2026-09-14T11:50:35Z (3 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
C. Wang (IHEP), W. Xie (NAOC), N. Dagoneau (CEA), D. Götz (CEA), C. Plasse (HKU), K. Liu (GXU), Y. Ma (NAOC), report on behalf of the SVOM mission team:
At 2026-09-14T11:12:31 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260914A (SVOM burst-id sb26091401). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network.
The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 9 alerts. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 12.81 in the [5-20] keV energy band over a time window of 10.20 seconds starting at 2026-09-14T11:12:27.
The localization of the best alert is R.A., Dec. 31.5419, 29.2616 degrees:
R.A. (J2000) = 2h06m10.06s
Dec. (J2000) = 29d15m41.72s
with a 90% confidence level (C.L.) radius of 6.33 arcmin (including systematic error of 2 arcmin added in quadrature).
This burst also triggered SVOM/GRM at 2026-09-14T11:12:32 on a timescale of 1 seconds with an SNR of 9.30.
The SVOM/GRM light curve showed a single narrow peak structure with a T90 duration of about 4.327 (-0.558 +2.287). The lightcurve of GRM could be found in the link below: https://www.bursthub.cn/gcn/2026/svgrb260914A.png
SVOM slewed to the burst. MXT and VT began observing the field after the slew. The analysis of the data will be published in a future circular.
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 Yinuo Ma: mayn@bao.ac.cn .
Please contact the BA by email if you require additional information.