HD 169981 - an overlooked photometric binary?

In 1999 and 2000 we obtained spectroscopic and photometric observations of the A-type binary star HD 169981. The observations were part of a campaign to search for short-term photometric and radial-velocity variations among e arly-type binaries. From the radial velocities of 18 metal lines we derived more precise orbital elements. Quite unexpectedly, our photometric data sh ow a dip that could be caused by an eclipse. The same feature is also visib le in the Hipparcos data. From our analysis of the available observations w e have estimated the physical parameters of the binary. Neither the spectro scopic nor the photometric observations hint at any short-term variations.