Determination of non-linear effects of limb-darkening in eclipsing variables from observations of their light minima

The aim of the present note is to point out that observations of eclipsing variables within minima do not, in general, allow a separation of the quadratic terms of limb-darkening from the first-order effects of the gravity-darkening of distorted components undergoing eclipse. Only a difference of the two can be deduced from the observations, but — especially in close binaries — the net effect will be dominated by gravity-darkening.