GRB 260909A: Multi-instrument gamma-ray burst with fading X-ray source detected

AI Summary

SVOM detected GRB 260909A on 2026-09-09 at 11:18:01 UTC with ECLAIRs (SNR=12.1, 8-50 keV) and GRM instruments, localized to RA=13.0009°, Dec=24.2188°. The burst exhibited multi-peak structure with T90=26.6s and fluence of 4.85e-06 erg/cm² (10-1000 keV), with spectral properties (Epeak=37 keV) consistent with typical GRBs. MXT follow-up identified an uncatalogued fading X-ray source (EPF_J005208.3+241147) with 0.5-10 keV flux of 4.07e-12 erg/cm²/s, while extensive optical follow-up from multiple ground-based telescopes (KAIT, VLT, Xinglong, OHP) yielded only upper limits (mag>20.5-24.3), with one tentative optical candidate at R=21.6 mag from Mondy requiring confirmation.

Measurements

Notices (1)

SVOM — GRB · Wed, 09 Sep 2026 11:21:14 GMT

GCN Circulars (10)

GCN-45549 — GRB 260909A · Thu, 10 Sep 2026 17:35:32 GMT
The Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory observed the field of GRB 260909A but did not detect any new optical source with a limiting magnitude of ~20.5, 31.5 minutes after the burst. This non-detection provides constraints on the optical afterglow of the gamma-ray burst.

GCN-45546 — GRB 260909A · Thu, 10 Sep 2026 09:27:50 GMT
The 1.93-m T193 telescope at the Observatoire de Haute-Provence observed the field of GRB 260909A, obtaining a 3 sigma limiting magnitude of z = 23.25. A faint source detected within the error region is likely not the GRB afterglow due to its consistent brightness in archival data.

GCN-45545 — GRB 260909A · Thu, 10 Sep 2026 08:23:43 GMT
The Stargate collaboration observed the field of GRB 260909A using the VLT, obtaining upper limits in the z, Y, J, and H bands, with no new sources detected. The observations were conducted in response to early optical upper limits reported by Li et al. and aimed to identify any optical or near-infrared counterparts to the gamma-ray burst.

GCN-45543 — GRB 260909A · Thu, 10 Sep 2026 01:38:50 GMT
The Einstein Probe (EP) performed a follow-up observation of GRB 260909A, detecting an uncataloged fading X-ray source within the error region identified by SVOM/MXT. The source, named EPF_J005208.3+241147, has a 0.5-10 keV flux of 4.07e-12 erg/cm^2/s, indicating significant X-ray activity.

GCN-45539 — GRB 260909A · Wed, 09 Sep 2026 17:02:11 GMT
The SVOM/VT telescope conducted observations of GRB 260909A, a gamma-ray burst detected by multiple instruments, but no credible optical candidates were identified within the error box. The observations set upper limits on the optical brightness of the burst, with magnitudes greater than 23.0 in the VT_B band and 22.8 in the VT_R band, encouraging deeper follow-up observations.

GCN-45538 — GRB 260909A · Wed, 09 Sep 2026 16:19:04 GMT
The SVOM/GRM instrument detected GRB 260909A, a gamma-ray burst with a multi-peak structure and a duration of 26.6 seconds. The burst's spectrum was best fitted with a power law function and an exponential high-energy cutoff, with a fluence of 4.85e-06 erg/cm^2 in the 10-1000 keV band.

GCN-45537 — GRB 260909A · Wed, 09 Sep 2026 16:14:01 GMT
Astronomers observed the field of GRB 260909A, a gamma-ray burst detected by SVOM, using the 1.6-meter AZT-33IK telescope at the Sayan Solar Observatory. They identified an uncatalogued object with a magnitude of 21.6 in the R band, suggesting it as a potential afterglow of the GRB, and encourage further observations to confirm this candidate.

GCN-45536 — GRB 260909A · Wed, 09 Sep 2026 15:59:21 GMT
The Xinglong 2.16m telescope observed the field of GRB 260909A and did not detect any uncatalogued source down to a 3-sigma upper limit of about 20.6 mag in the R-band, consistent with previous observations by SVOM/C-GFT. The observations were conducted approximately 1.86 hours after the initial trigger.

GCN-45535 — GRB 260909A · Wed, 09 Sep 2026 15:17:49 GMT
The SVOM/C-GFT team reported an optical upper limit for GRB 260909A, with no credible candidate detected in the i-band imaging. The observation, conducted approximately 21.61 minutes after the trigger, set an upper limit of i > 20.1 AB (3-sigma) for the event.

GCN-45534 — GRB 260909A · Wed, 09 Sep 2026 11:52:24 GMT
The SVOM mission detected a gamma-ray burst, GRB 260909A, on September 9, 2026, at 11:18:01 UTC. The burst was observed by multiple instruments, including ECLAIRs and GRM, and an uncatalogued X-ray source was identified by the MXT instrument.