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tokens: fact that we do not know the interstellar reddening for most of these stars, and that the assumed spectral types were only derived on the basis of their photometric indices (i.e. a kind of lower limit). However, the stars having early spectral types have mostly been studied during the last century, and it is only during the last decades with the use of large telescopes did the focus of stellar astronomers shift to the more late and fainter systems. We also have more systems with longer orbital periods (> 30 d) than appear in Bulut Demircan (2007) . Fig. 3. Distribution of omega angles with respect to the eccentricity. We can also address the issue of selection effects for our sample of stars. These “serendipitous” discoveries should be more likely detected as eccentric when the two minima are displaced from their positions 0.0 and 0.5 in phase diagram, but the binaries which have ω close to 90° or 270° should be only rarely detected. This can more easily be done when the photometry is sufficiently precise and also when the eccentricity is higher (i.e. the durations of both eclipses are significantly different). Hence, we tried to test this distribution of ω versus eccentricity in our Fig. 3 . One can see that the diagram is almost uniformly covered with data points, but the number of systems with higher eccentricity is still rather low (see Sect. 4 ). 4. Period eccentricity relation The diagram which should be discussed in more detail is the period-eccentricity distribution of our systems. We plotted our results together with those already published before by Bulut Demircan (2007) and also with the spectroscopic binaries from the SB9 catalogue by Pourbaix et al. (2004) in the Fig. 4 . As can be seen, orbital circularization plays a role in binaries with shorter periods ( Raghavan et al. 2010 , Duchêne Kraus 2013 ), while practically all systems that have periods below one day are already circular. Besides the plotted observed data we have also plotted several solid lines representing the limits of very close periastron approaches of both components (i.e. 1.5 × R ⋆ ) when these likely collide with each other. These periastron distances were computed for different spectral types (B to M) according to their typical radii and masses (see Zombeck 1990 ) with the assumption that both components are similar to each other (same masses and radii). As we can see, the sample of eclipsing apsidal motion systems has increased significantly with our new data set and should be very helpful in future when analysing the P-e diagram in detail. However, we still have to be very careful when interpreting these results with our new data. For some systems a significant change of eccentricity could appear for the case when the star still has poor data coverage of both light curve and the O–C diagram. The P-e diagram still lacks of such systems which have significant eccentricity close to its upper limit for a particular period. The system with the highest