Top: The complete set of Johnson ﹩\Delta V﹩ differential magnitudes for BD −10°3166 plotted against orbital phase of the companion. The predicted depth and duration of a planetary transit are shown schematically. The star has no light variability on the planetary period larger than about 0.0008 mag. Bottom: The observations around the phase of predicted transit are replotted with an expanded scale on the abscissa. The error bars are described in the text. Transits deeper than about 0.0002 mag or so are ruled out by these observations.