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Astron. Astrophys. 338, 1031-1040 (1998)

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2. Photometry

HD 81410 was observed on a total of 40 nights - in [FORMULA] during April 1987 and May 1988, and in uvby during June 1988 and January 1990 - at the European Southern Observatory (ESO), La Silla, Chile, using the 50 cm ESO Cassegrain telescope. HD 81904 and HD 80991 were observed as the comparison stars through out, and all the observations were made differentially with respect to the former. The probable errors in the differential BVRI magnitudes are typically around 0.005 mag, while those in U and uvby are slightly higher. The average UBVRI and uvby magnitudes of the comparison stars obtained from the observations of several runs are given in Table 1, and the differential measurements of HD 81410 were converted to UBVRI and uvby magnitudes using the corresponding values of HD 81904.


Table 1. UBVRI and uvby magnitudes of the comparison stars of HD 81410

The Julian days of observation were converted into photometric phases using the following ephemeris:


where the initial epoch corresponds to the conjunction with the primary in front calculated from its time of maximum radial velocity and the period is the orbital period (Weber & Strassmeier 1998). The V and y magnitudes, and the various colours obtained by us are plotted in Figs. 1a,d,h; the observations obtained by Sterken et al. (1993) close to the period of our observations are also plotted in Fig. 1h.

[FIGURE] Fig. 1a-h. Light and colour curves of HD 81410; the mean epochs of observation are indicated (see Table 2 for the references). The smooth continuous curves represent the results of spot modeling

[FIGURE] Fig. 1a-h. (continued)

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© European Southern Observatory (ESO) 1998

Online publication: September 17, 1998