  We report generation of a femtosecond supercontinuum extending from the
ultraviolet to the near-infrared and detection of its carrier-envelope phase
variation by f-to-2f interferometry. The spectrum is generated in a gas-filled
hollow-core photonic crystal fiber where soliton dynamics allows CEP-stable
self-compression of OPCPA pump pulses at 800 nm to a duration of 1.7 optical
cycles, followed by dispersive wave emission. The source provides up to 1
{\mu}J of pulse energy at 800 kHz repetition rate resulting in 0.8 W of average
power, and can be extremely useful for example in strong-field physics,
pump-probe measurements and ultraviolet frequency comb metrology.
