BH Vir 
, is a detached,
main sequence, late type, double line eclipsing binary.
In spite of lot of observing effort done up to now, mass, radius,
temperatures and abundances
are poorly defined in the low mass range where
only a few stars have astrophysical parameters calculated with the
required accuracy for a detailed evolutionary modelling.
With this aim, we have performed a 6 year monitoring
program to obtained good photoelectric uvby and H
light curves for late-type binary systems, Clement et al. (1997).
BH Vir was a good candidate and was thus included in our
program of absolute parameters determination for late-type binary systems.
Photometric studies of the interesting eclipsing binary BH Vir have been carried out by several authors: Kitamura et al. (1957), Koch (1967), Sadik (1978), Botsula (1978), Hoffmann (1982), Guiricin et al. (1984), Scaltriti et al. (1985), and Derman et al. (1989). Recently in a detailed analysis of the available light curves using the Wilson-Devinney code, Zhai et al. (1990) derived the most relevant astrophysical parameters of both components. More recently, Vincent (1993), using surface imaging techniques includes BH Vir in the list of binary systems that show occultation of the secondary star by the primary star, that is, the secondary eclipse of BH Vir is total. The analysis of the photometric light curves for BH Vir is a difficult task mainly due to the large and very fast amplitude variations outside eclipses. Koch (1967) reported changes in the depth of the primary eclipse of a tenth of a magnitude, in only few days. Although we observed a variation of the same order between the last two campaigns, we found, however, no appreciable variations of the light curves within the short time interval of each campaign (weeks). Despite its showing intrinsic variability, BH Vir has been included in our program due to the lack of late-type eclipsing binaries without photometric variations outside eclipse. Relevant photometric elements can be extracted for such systems too, once the light curves have been cleaned of the activity waves attributed to the presence of spots in the stellar surface. To attain the maximum accuracy in the determination of the astrophysical parameters when analysing binary systems affected by activity, we have implemented a new iterative method to estimate more accurately the contribution of activity.
In this paper we present accurate and complete photoelectric uvby and
H
light curves for BH Vir, whose light curve has been fully
covered at least three times in four different epochs.
A complete analysis of BH Vir based on these data will be published separately.
Table 1: Standard photometry for BH Vir and the comparison stars
Figure 1: BH Vir differential light curve. y filter