2 The reduction and analysis

On the basis of the measurements of 18 comparison stars we have constructed the sensitometric characteristic for each plate, with the help of which the photographic magnitudes of the individual stars studied were determined. The results obtained that way for 17 investigated stars, along with the Asiago magnitudes are summarized chronologically in Table 2. The standard deviations of sensitometric characteristics of each plate are in the interval $<0.03-0.27\gt m_{\rm pg}$. with mean value $0.13\ m\rm _{pg}$.The cross-reference between star No., MS designation and catalogue one (provided it has already been adopted for a given star) according to the GCVS and IBVS (Kholopov et al. 1987) is given in Table 3 as well as the equatorial coordinates for the epoch J1950.0 for each star, which is compatible with the GCVS. In this table are shown the basic characteristics of the observational material for each star: the number of data points and interval of magnitudes obtained at the Asiago Observatory (A) and Skalnaté Pleso Observatory (SP) respectively. We have performed the period analysis of both the data groups A and SP respectively. Some data were omitted for the period analysis on the basis of the quality of the photographic plates. We have used the method of Fourier analysis (Deeming 1975; Kurtz 1985), the phase dispersion minimization method (Stellingwerf 1978) and the method of Fourier harmonic analysis (Andronov 1995) which fits the first harmonic term of a trigonometric polynome to the observed data. The advantage of the last method is the fact that it provides one not only with the determination of the parameters of variability alone, but also with the determination of the corresponding errors. A further result of the analysis is the determination of the moments of maxima (eventually minima) of the light changes through the routine by R. Komzík (1995), making use of the following methods: the parabola fit, the polynomial fit, the "center of mass", Kwee & Van Woerden (1956), the sliding integrations and the tracing paper - polygonal line. The averages of values obtained through the individual methods were considered as the resulting values. The moments of maxima and minima are determined in the vicinity of the center of the observational interval. The type of the variability was determined as the last parameter, on the basis of the length of the period, the amplitude of light changes, the shape of LC and with the help of the characteristics defined in the GCVS.