  The star HD144548 (=HIP~78977; TYP~6212-1273-1) has been known as a detached
eclipsing binary and a bona-fide member of the Upper Scorpius OB association.
Continuous photometry from the K2 mission on Campaign Two has revealed the
presence of additional eclipses due to the presence of a third star in the
system. These are explained by a system composed of the two previously known
members of the eclipsing system (Ba and Bb) with a period of 1.63 d, orbiting
around an F7-F8V star with a period of 33.945 +/- 0.002 d in an eccentric orbit
(e_A = 0.2652 +/- 0.0003). The timing of the eclipses of Ba and Bb reveals the
same 33.9 d periodicity, which we interpret as the combination of a light time
effect combined with dynamical perturbations on the close system. Here we
combine radial velocities and analytical approximations for the timing of the
eclipses to derive masses and radii for the three components of the system. We
obtain a mass of 1.44 +/- 0.04 M_sun and radius of 2.41 +/- 0.03 R_sun for the
A component, and almost identical masses and radii of about 0.96 M_sun and 1.33
R_sun for each of the two components of the close binary. HD144548 is the first
triply eclipsing system for which radial velocities of all components could be
measured.
