Program: GN-2023B-Q-130

Fast blue optical transients (FBOTs) are a poorly understood class of extragalactic transient. They are at odds with being radioactively powered due to their rapid rise and fall timescales, and are very blue, indicating a high photospheric temperature. Faint FBOTs are now routinely detected, but bright, local events are rare. Only four were followed up with X-ray, optical spectroscopic, and radio observations in the last four years, of which only two had early time multi-wavelength observations. We propose a ToO joint programme (with Chandra, Gemini, JVLA and HST) to follow-up a single bright FBOT in detail. Our proposal will help to discern which features all FBOTs have in common, and will put strong constraints on the nature of the central engine and emission mechanisms.