Lightcurves and poles of seven asteroids

The Asteroids 5 Astraea, 19 Fortuna, 51 Nemausa, 68 Leto, 138 Tolosa, 196 Philomela and 409 Aspasia have been studied using Strِmgren photometry observations made in 1997. Simultaneous lightcurves in the uvby Strِmgren filters of synodic periods of 0.70004 ± 0.00020, 0.31013 ± 0.00003, 0.32400 ± 0.00020, 0.61910 ± 0.00100, 0.42087 ± 0.00009, 0.34750 ± 0.00020 and 0.37576 ± 0.00060 days, and amplitudes, in the y filter, of 0. m 16 ± 0. m 05, 0. m 30 ± 0. m 02, 0. m 15 ± 0. m 04, 0. m 29 ± 0. m 02, 0. m 43 ± 0. m 03, 0. m 30 ± 0. m 04 and 0. m 15 ± 0. m 06 have been found for 5 Astraea, 19 Fortuna, 51 Nemausa, 68 Leto, 138 Tolosa, 196 Philomela and 409 Aspasia, respectively. Additional observations of 138 Tolosa and 196 Philomela during February 2000, show lightcurve amplitudes equal or greater than 0. m 15 for 138 Tolosa and of 0. m 45 for 196 Philomela in 2000 opposition. ons for the sense of rotation, sidereal period, pole orientation and shape properties have been proposed for the first time for 138 Tolosa and improved solutions have been obtained for 5 Astraea, 19 Fortuna, 51 Nemausa, 196 Philomela and 409 Aspasia.