Context :

Aims : In this paper we present the first results of a detailed spectroscopic and photometric analysis of the V = 11.7 ^ { m } eclipsing binary ASAS~J052821+0338.5 .

Methods : With the FIES spectrograph at the Nordic Optical Telescope we have obtained a series of high-resolution spectra ( R \approx 47000 ) covering the entire orbit of the system .
In addition we obtained simultaneous broadband photometry from three small aperture telescopes .
From these spectroscopic and photometric data we have derived the system ’ s orbital parameters and determined the fundamental stellar parameters of the two components .

Results : Our results indicate that ASAS J052821+0338.5 is a K1/K3 pre-main-sequence eclipsing binary , with component masses of 1.38 { M } _ { \sun } and 1.33 { M } _ { \sun } and a period of 3.87 days , located at a distance of 280 \pm 30 pc .
The kinematics , physical location and the evolutionary status of the two stars suggest that ASAS J052821+0338.5 is a member of the \sim 11 Myr old Orion OB1a subassociation .
The systems also exhibits smooth \sim 0.15 ^ { m } out-of-eclipse variations that are similar to those found in RS CVn binaries .
Furthermore the parameters we derived are consistent with the 10 – 13 Myr isochrones of the popular Baraffe stellar evolutionary models .

Conclusions :