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GRB 260917B detected by SVOM with refined analysis showing broad spectral bump and X-ray counterparts
AI Summary
GRB 260917B was detected by SVOM/ECLAIRs with a duration of 35 seconds and a power-law spectral model. Follow-up observations revealed a broad bump in the light curve and multiple X-ray counterparts, including one consistent with an optical transient.
Measurements
| Event | GRB 260917B |
|---|---|
| Event ID | sb26091701 |
| Source | SVOM |
| Alert type | GRB |
| Significance | high |
| Trigger time (UTC) | Thu, 17 Sep 2026 03:52:11 GMT |
| Right ascension (J2000) | 46.8646° |
| Declination (J2000) | 25.4836° |
| Position error radius | 0.1473° (8.8′) |
| GCN notices | 1 |
| GCN circulars | 9 |
Observations (15)
Values parsed from the Circular text; each row names its Circular.
| Time since trigger | Band | Value | Telescope | Circular |
|---|---|---|---|---|
| T+17 min | R_C | > 17 Vega mag (limit) | FRAM-Auger | GCN 45617 |
| T+61 min | SDSS r | 21.34 ± 0.11 AB mag | LCO 1m | GCN 45608 |
| T+61 min | Pan-STARRS z | 20.16 ± 0.14 AB mag | LCO 1m | GCN 45608 |
| T+92 min | r | 21.29 ± 0.06 AB mag | SVOM/COLIBRÍ (FM-GFT) | GCN 45607 |
| T+92 min | z | 19.84 ± 0.06 AB mag | SVOM/COLIBRÍ (FM-GFT) | GCN 45607 |
| T+116 min | R_C | > 17.9 Vega mag (limit) | FRAM-Auger | GCN 45617 |
| T+2.4 h | J | 19.02 ± 0.23 AB mag | Palomar 1-m | GCN 45611 |
| T+2.8 h | VT_B | 22.7 ± 0.2 AB mag | SVOM/VT | GCN 45610 |
| T+3.9 h | 0.5-10 keV | 7.56e-14 ± 2.67e-14 erg/cm^2/s | EP-FXT | GCN 45625 |
| T+3.9 h | 0.5-10 keV | 5.91e-14 ± 2.39e-14 erg/cm^2/s | EP-FXT | GCN 45625 |
| T+3.9 h | 0.5-10 keV | 5.03e-14 ± 1.58e-14 erg/cm^2/s | EP-FXT | GCN 45625 |
| T+3.9 h | 0.5-10 keV | 1.97e-13 ± 4.29e-14 erg/cm^2/s | EP-FXT | GCN 45625 |
| T+3.9 h | 0.5-10 keV | 8.03e-14 ± 2.21e-14 erg/cm^2/s | EP-FXT | GCN 45625 |
| T+3.9 h | 0.5-10 keV | 6.96e-13 ± 1.83e-13 erg/cm^2/s | EP-FXT | GCN 45625 |
| T+16.6 h | R | > 21.5 Vega mag (limit) | AZT-33IK | GCN 45631 |
Notices (1)
SVOM — GRB · Thu, 17 Sep 2026 03:52:11 GMT
GCN Circulars (9)
GCN-45681 — GRB 260917B
· Mon, 21 Sep 2026 14:58:07 GMT
The SVOM/ECLAIRs team reported a refined analysis of GRB 260917B, a gamma-ray burst detected on September 17, 2026, with a duration of 35 seconds and a time-averaged spectrum best fitted by a power-law model. The burst showed a broad bump from 18 seconds before to 17 seconds after the trigger time, with significant fluence and photon flux measurements.
GCN-45631 — GRB 260917B
· Fri, 18 Sep 2026 13:51:45 GMT
The field of GRB 260917B was observed with the AZT-33IK 1.5m telescope at the Sayan Solar Observatory, but the optical counterpart previously reported was not detected, with an upper limit magnitude of 21.5 in the R filter. This non-detection provides constraints on the optical emission of the gamma-ray burst.
GCN-45625 — GRB 260917B
· Fri, 18 Sep 2026 10:20:25 GMT
The Einstein Probe (EP) performed a follow-up observation of GRB 260917B, detecting six uncataloged X-ray sources within the error region, with one source showing a declining X-ray flux consistent with an optical counterpart candidate. This observation was part of a broader multi-instrument campaign following the initial detection by SVOM/ECLAIRs.
GCN-45617 — GRB 260917B
· Thu, 17 Sep 2026 23:15:49 GMT
nap
GCN-45611 — GRB 260917B
· Thu, 17 Sep 2026 10:21:46 GMT
A team of astronomers observed the field of GRB 260917B in the near-infrared J band using the Palomar 1-m telescope equipped with the WINTER camera, detecting a faint source at the optical counterpart position with a magnitude of J = 19.02 +- 0.23 mag (AB). This detection provides valuable data for studying the afterglow of the gamma-ray burst.
GCN-45610 — GRB 260917B
· Thu, 17 Sep 2026 09:05:04 GMT
The SVOM/VT telescope detected the optical counterpart of GRB 260917B, showing a power-law decay with a red color, suggesting a medium redshift. The AB magnitudes measured were 22.7+/-0.2 in the VT_B band and 20.8+/-0.1 in the VT_R band.
GCN-45608 — GRB 260917B
· Thu, 17 Sep 2026 08:36:34 GMT
The SVOM mission team observed GRB 260917B using the LCO 1m telescope at Teide Observatory, detecting the optical candidate with magnitudes r = 21.34 and z = 20.16. The observations were conducted approximately 1.02 hours after the initial detection, providing crucial data for further analysis.
GCN-45607 — GRB 260917B
· Thu, 17 Sep 2026 08:10:04 GMT
nap
GCN-45606 — GRB 260917B
· Thu, 17 Sep 2026 04:33:30 GMT
nap
AI summary generated Thu, 29 Oct 2026 23:07:42 GMT.