3 Discussion

For most of the binaries discussed here, the presented data provide a significant improvement of the ephemeris. In case of AQ Cir, our observations might be helpful in findig an accurate value for the orbital period. Moreover, the collected data allow for a discussion of the scatter of times of minima. Our results suggest that for some binaries, this scatter is considerably larger than are the errors of measurements, whereas for other systems the scatter is comparable to these errors. We calculated the scatter of minimum times around the linear parts of ephemeris; the scatter is large for all binaries where such calculation was possible: V337, V1182, V1331 Aql and V382 Cyg. The scatter is large for AH Cep too (calculated after the effect of the third body had been removed). The rms values rise from 0$.\!\!^{\rm d}$0033 for V382 Cyg to 0$.\!\!^{\rm d}$0071 for V1331 Aql. IU Aur is known for a scatter of minimum times (0$.\!\!^{\rm d}$0012, after the effect of the third body is subtracted) only a little larger than are the measuring errors, and such a behaviour is present also for V606 Cen (scatter 0$.\!\!^{\rm d}$00045, average m.e. 0$.\!\!^{\rm d}$00032) studied in a paper by Lorenz et al. (in preparation).

According to other data it seems that for all five binaries with large scatter, the light curve is intrinsically variable, in some cases (V337 Aql) it is also asymmetric.