General information
GRB 260616C was detected at 2026-06-16T14:47:01.950 UTC by GECAM-B and at 14:47 UT by MAXI/GSC as a bright uncatalogued X-ray transient near RA 67.745 deg, Dec 9.294 deg. MAXI tentatively also names the source MAXI J0430+092 and notes possible ambiguity between a GRB and a new X-ray transient source.
Wavelength coverage
- X-ray: MAXI/GSC detected a bright uncatalogued source with an averaged 4.0-10.0 keV flux of 148 +- 33 mCrab during the scan.
- Gamma-ray / hard X-ray: GECAM-B detected a burst in about 70-6000 keV with T90 = 29.5 +3.5/-4.5 s and a 10-1000 keV fluence of (1.99 +0.30/-0.26)E-04 erg/cm^2.
No observations are mentioned in optical, infrared, radio, neutrino, or gravitational-wave bands.
Lightcurve and spectrum
- GECAM-B light curves show the burst mainly consists of a pulse with T90 = 29.5 +3.5/-4.5 s in about 70-6000 keV.
- The GECAM-B time-averaged spectrum from T0-4 s to T0+8 s is best fitted by a power law with photon index -2.32 +0.16/-0.13.
- The GECAM-B 10-1000 keV fluence over T0-4 s to T0+8 s is (1.99 +0.30/-0.26)E-04 erg/cm^2.
- MAXI/GSC reports marginal possible excesses of about 50 mCrab in previous and next scans at 13:14 UT and 16:20 UT, but says these occurred during large background variations and their significance is unclear.
Redshift
What’s special vs typical
- The event is relatively notable because it has both MAXI/GSC and GECAM-B detections and a high reported gamma-ray fluence.
- MAXI's possible multi-scan activity creates an atypical ambiguity: the source may be a new X-ray transient rather than a straightforward GRB.