Einstein Probe detects X-ray transient EP260731a with no optical counterpart.

AI Summary

The Einstein Probe's WXT detected an X-ray transient (EP260731a) with a net count rate of 0.56 counts/s, later confirmed by FXT. Follow-up optical observations by COLIBRÍ and NOT found no transient within the expected location.

Measurements

Notices (1)

Einstein Probe WXT — GRB · Fri, 31 Jul 2026 00:54:24 GMT

GCN Circulars (3)

GCN-45264 — EP260731a · Fri, 31 Jul 2026 07:24:07 GMT
The COLIBRÍ telescope observed the field of EP260731a and did not detect any new source at the FXT source position, setting a 5-sigma upper limit of z > 20.9. This non-detection is consistent with previous reports and further observations are ongoing.

GCN-45263 — EP260731a · Fri, 31 Jul 2026 04:39:27 GMT
The Nordic Optical Telescope (NOT) observed the field of EP260731a, detected by EP, and found no optical transient within the error circle down to a 5-sigma limiting magnitude of z ~ 19.8, 2.46 hours post-trigger. The observation was conducted under challenging conditions with the target 16 degrees from a 98% illuminated moon.

GCN-45261 — EP260731a · Fri, 31 Jul 2026 02:15:53 GMT
The Einstein Probe (EP) mission has detected an X-ray transient, designated EP260731a, using its Wide-field X-ray Telescope (WXT). A follow-up observation with the Follow-up X-ray Telescope (FXT) confirmed an uncatalogued X-ray source within the WXT error circle, indicating a significant astronomical event.