We describe the extension of our Doppler imaging technique to the case of eclipsing binary systems. Using numerical experiments, we show that the simultaneous imaging of both components breaks the north-south ambiguity that occurs for single stars with high inclination. Characteristic map distortions can be used to correct errors in the orbital parameters of the binary.
We apply this technique to ER Vul – an active RS CVn type binary. Our preliminary results show the presence of the hot spots on the substellar sides of both components, perhaps due to the reflection effect.
We also discuss application of the same technique to contact binaries, where non-sphericity is significant.