SVOM detects long-duration GRB 260909A with multi-wavelength follow-up

AI Summary

GRB 260909A was detected by SVOM/ECLAIRs on 2026-09-09 at 11:18:01 UTC with a 47-second duration in the 4-120 keV band and photon index of -1.23. The burst showed multi-peak structure with fluence of 9.4e-6 erg/cm² and was localized to RA=13.0009°, Dec=24.2188° with 6.67 arcmin error radius. Extensive multi-wavelength follow-up detected an X-ray afterglow via Einstein Probe and radio counterpart via ATCA, while optical observations set deep upper limits (z>24.3 mag), indicating a dark GRB or heavily obscured afterglow.

Measurements

Notices (1)

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

GCN Circulars (17)

GCN-45704 — GRB 260909A · Wed, 23 Sep 2026 14:06:52 GMT
The Australia Telescope Compact Array (ATCA) has detected a radio counterpart to the Gamma-Ray Burst (GRB) 260909A, with preliminary measurements at 7.2, 9.1, and 11.0 GHz. The positive spectral index suggests the spectral peak of the afterglow is above the ATCA observing band, indicating ongoing observations for further study.

GCN-45597 — GRB 260909A · Wed, 16 Sep 2026 18:28:12 GMT
The NOEMA interferometer detected a source consistent with the X-ray afterglow of GRB 260909A at a combined flux density of approximately 0.4 mJy, with a spectral slope of beta ~ -1.3. The source's coordinates are R.A. = 00:52:08.462 and Dec. = +24:11:47.12, with an uncertainty of ~ 0.2 arcseconds.

GCN-45593 — GRB 260909A · Wed, 16 Sep 2026 11:20:41 GMT
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GCN-45556 — GRB 260909A · Sat, 12 Sep 2026 21:03:53 GMT
Following the detection of GRB 260909A by SVOM/ECLAIRs, observations were conducted using the 2.2m CAHA telescope, 1.5m OSN telescope, and 10.4m GTC telescope. No optical transient was detected in any of the observations, with upper limits ranging from z = 21.13 to z = 24.55 mag.

GCN-45554 — GRB 260909A · Fri, 11 Sep 2026 20:58:57 GMT
The field of GRB 260909A was observed with the Shajn 2.6-meter telescope and the AS-32 0.7-meter telescope, but no new optical sources were detected. The suggested source is no longer considered a candidate for the optical counterpart of GRB 260909A, and the results align with upper limits obtained by other observatories.

GCN-45553 — GRB 260909A · Fri, 11 Sep 2026 14:27:15 GMT
The SVOM/ECLAIRs team reported a refined analysis of GRB 260909A, a gamma-ray burst with a multiple peak lightcurve and a duration of 47 seconds. The burst's spectrum is best fitted by a power-law model with a photon index of -1.23, indicating significant energy release in the 4-120 keV range.

GCN-45551 — GRB 260909A · Fri, 11 Sep 2026 07:04:33 GMT
Swift has initiated a Target of Opportunity (ToO) observation of the gamma-ray burst GRB 260909A, initially detected by SVOM/ECLAIRs. Automated and manual analyses of XRT data will be conducted to identify any potential afterglow candidates, with results to be reported online and via GCN Circulars.

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.