5 Conclusions

Lightcurves of asteroids 40 Harmonia, 45 Eugenia and 52 Europa from September to October 1997 are presented using uvby Strömgren photometry. The lightcurves obtained for these three asteroids show very regular shapes with two maxima and two minima per cycle. Although in all the cases the two peaks are of slightly different amplitudes. The absolute magnitudes and colour indices obtained agree well with previous measurements. No significative tendencies are found in the colour indices during their rotational phases. The values for the linear phase coefficients and for the multiple scattering factors obtained for 40 Harmonia and 52 Europa are in good agreement with the mean values expected for S-type and C-type asteroids, respectively. However, for 45 Eugenia a multiple scattering factor greater than the mean values expected for C-type asteroids (also for U-type) is obtained.

Values of sidereal periods, poles and shapes parameter are proposed. However lightcurves taken at different ecliptic longitudes and at different solar phase angles would help to obtain more accurate rotational and shape solutions.

Acknowledgements

This research was partially supported by the Comisión Interministerial de Ciencia y Tecnología under contracts ESP97-1773-C03-01 and ESP97-1798, the Junta de Andalucía and the Dirección General de Enseñanza Superior (DGES) under project PB96-0840. This research has made use of the Asteroid Photometric Catalogue database. We very gratefully acknowledge the staffs of Sierra Nevada Observatory for their help during the run of observations. Acknowledgements are also especially made to M.C. Romero for making available many papers used in this investigation and to V.G. Brown for proofreading. We wish to thank the referee, J. Berthier, for useful comments and suggestions.