Overview

• Researchers report in Astrophysical Journal Letters that FRB 20250316A, nicknamed RBFLOAT, is the brightest fast radio burst yet detected.
• The burst, spotted on March 16, 2025, has been localized to the spiral galaxy NGC 4141 in Ursa Major at roughly 130 million light-years.
• Using the newly completed CHIME Outriggers with continent-scale baselines, the team achieved tens-of-milliarcsecond precision, about 13 parsecs at the source distance.
• Imaging places the origin on a spiral arm at the edge of a star-forming region, a location consistent with possibilities such as a slightly older magnetar.
• A search of six years of CHIME observations found no prior events from this position, indicating a nonrepeating source so far and motivating extensive follow-up.