GRB 260225A

General information

GRB 260225A was triggered by SVOM/ECLAIRs at 2026-02-25 08:51:15 UTC and subsequently followed up with detections of an optical and X-ray counterpart consistent with the burst localization.

Wavelength coverage

• Gamma-rays / hard X-rays: SVOM/ECLAIRs trigger and spectral/fluence analysis; SVOM/GRM detection reported.
• X-rays: EP/FXT detected a coincident uncatalogued X-ray source and reported flux and photon index.
• Optical: SVOM/COLIBRÍ and SVOM/VT reported detections and limits in r/z and VT_B/VT_R bands.
• Near-IR: WINTER reported a J-band upper limit. No observations were mentioned in radio, UV, GeV/TeV gamma-rays, or spectroscopy.

Lightcurve and spectrum

• SVOM/ECLAIRs prompt emission: single-peak lightcurve; duration ~59 s (4–120 keV, imaging, pre-slew), with emission below 20 keV seen up to T0+209 s.
• ECLAIRs time-averaged spectrum (T0-21 s to T0+38 s; 5–120 keV): broken power-law with photon index1 = -1.00 (+0.20/-0.16), break energy = 21.7 (+4.4/-3.9) keV, photon index2 = -2.06 (+0.22/-0.28); 4–120 keV fluence = (1.00 +0.04/-0.26)×10^-6 erg/cm^2.
• Optical: COLIBRÍ reports r=21.55 for an uncatalogued source; SVOM/VT reports VT_B=22.09±0.16 and VT_R=22.00±0.20 at ~1.1 hr, and later VT_B=23.6±0.3 with VT_R>23.3 at ~35 hr.
• X-ray: EP/FXT reports an absorbed power-law with photon index ~1.56 (Galactic NH) and unabsorbed 0.5–10 keV flux (1.89±0.23)×10^-12 erg cm^-2 s^-1.

Redshift

What’s special vs typical

SVOM/ECLAIRs analysis states the spectral parameters indicate the burst is likely an X-ray flash, and the afterglow is supported by consistent optical (COLIBRÍ, SVOM/VT) and X-ray (EP/FXT) detections.