V 839 Oph was included in our observing program in 1989 and since then the system was observed for 9 nights in 1989, 8 nights in 1990, 7 nights in 1991, 2 nights in 1992, 2 nights in 1993 and 3 nights in 1994. A journal of the observations is given in Table 1 (click here). Differential observations were obtained with a 30 cm Maksutov telescope of Ankara University Observatory equipped with an photometer head which is used with a Hamamatsu R1414 photomultiplier tube. Before Sept 29, 1991, the differential observation were made by using an photomultiplier attached to the Maksutov telescope. The filters used are in close agreement with the standard UBV bands.
The same comparison star and check star were chosen as Binnendijk (1960). All differential observations were reduced outside the atmosphere using the extinction coefficients calculated in the usual way, and heliocentric corrections were made for all the observations. The differential measurements in the sense variable minus comparison are listed in Table 2 (click here) (available in electronic form). The light curves formed by these observations in different years are shown in Fig. 1 (click here) together with the colour curves. No significant reddening in the B-V and U-B colour curves is detectable. Although the seasonal observations were obtained in short time intervals, the scatter in the observations, particularly in the U filter, was found larger than expected. This is due partly to the use of an old photometer (between 1989 and 1991) and to occasional bad weather conditions. The observed differences of the check star relative to the comparison star are given in Table 3 (click here). These uncertainties are much smaller in the 1992-1994 observations, which were secured with the new photometer head.
The phases were calculated by using new linear light elements, explained in the following section.
Figure 1: The light curves and colours of V 839 Oph in between 1989 and 1994