GRB 260726A

General information

GRB 260726A is a likely long GRB detected by Fermi/GBM at 2026-07-26 23:44:49 UT and independently detected/localized by SVOM/ECLAIRs, with SVOM/GRM also detecting the burst. Follow-up reports identify a faint optical candidate at RA=356.883196 deg, Dec=52.870077 deg, while the MXT X-ray counterpart is described as tentative.

Wavelength coverage

• Gamma-ray: Fermi/GBM triggered and reported a likely long GRB; SVOM/ECLAIRs and SVOM/GRM also detected it, with ECLAIRs SNR 14.47 in 8-50 keV.
• X-ray: SVOM/MXT reported a tentative faint fading source in the first orbit; EP-FXT later found no X-ray counterpart at the VT position, with a 0.5-10 keV flux upper limit of 1.16 x 10^(-13) erg cm^-2 s^-1.
• Optical: SVOM/VT detected an uncatalogued VT_R candidate at 21.4 +/- 0.2 AB mag at 1.95 hr and did not detect it in VT_B to 24.0 AB mag; Liverpool Telescope detected i=22.58 +/- 0.16 AB mag at 26.56 hr and reported r>22.03.
• Near-infrared: WINTER observed in J band and did not detect a new source at the SVOM/VT candidate position, with J>18.92 AB mag.
• Wide-field optical: MASTER-SAAO observed the Fermi error box starting about 3782 s after trigger and reported clear-band upper limits up to 17.5 mag. Bands with no observations mentioned: radio, submillimeter, millimeter, ultraviolet, gravitational-wave, neutrino.

Lightcurve and spectrum

• Fermi/GBM reported a single emission episode with T90 about 19 s in 50-300 keV.
• The GBM time-averaged spectrum from T0-3.6 to T0+23.8 s is best fit by a cutoff power law with index -1.27 +/- 0.05 and Epeak=121 +/- 6 keV.
• GBM fluence was (1.32 +/- 0.10)E-06 erg/cm^2 in 10-1000 keV, and the 1 s peak photon flux was 1.4 +/- 0.2 ph/s/cm^2 in 10-1000 keV.
• SVOM/VT reported a fading slope of about -0.2 in VT_R during its observations.

Redshift

What’s special vs typical