This page links to ASCII files giving the trajectory data of Rosetta. These files are kindly provided by Jose Rodriguez-Canabal, ESOC. 
The time format is so-called MJD2000. This is the number of days since 1 Jan 2000 at zero hours. The timescale is Barycentric Dynamical Time (TDB). 

The coordinate reference frame is the mean ecliptic and equinox of J2000.0. 

The format of the different columns is the following: 

1st column:  MJD2000 
2nd column: x-position in km 
3rd column: y-position in km 
4th column: z-position in km 
5th column: velocity in x-direction in km/s 
6th column: velocity in y-direction in km/s 
7th column: velocity in z-direction in km/s 

NOTE DE M GUIZIOU :
Lors des survols Terre les axes géocentriques et héliocentriques sont tous les deux de directions écliptiques