Top: 61 Vir light curve obtained by Spitzer to search for the transit of its planet b, divided for the best-fit phase-pixel model (here a third order x and y-position polynomial), unbinned (green dots) and binned to intervals of 0.005d (7.2 min). The start of the second AOR is represented by the red vertical line. Bottom: Lomb-Scargle periodogram showing a clear power excess at ~0.11 days and its first harmonic.