  We report on the first daytime on-sky results of a Phase Knife stellar
Coronagraph operated in the visible from the French-Italian Concordia station
at Dome C of Antarctica. This site has proven in the last few years to offer
excellent atmospheric seeing conditions for high spatial resolution
observations. The coronagraphic performances obtained from laboratory
experiments and numerical models have been compared with those measured from
daytime on-sky data recorded on bright single and multiple stars: Canopus (HD
45348), and alpha Centauri (HD 128620J). No correction system was used
(adaptive optics or tip-tilt mirror) so that atmospheric turbulence alone
defines the image quality, and thus the coronagraphic performances. Moreover,
the experiment could not run under optimal operational conditions due to
hardware/software problems. Satisfactory results have been obtained: broad band
total rejection exceeding 15 were attained in the visible. This first day-time
observation campaign yields an experimental feedback on how to improve the
instrument to get optimal performances during future night-time observation
runs.
