1998AJ....115.1160S

A complete photometric analysis of BVRI photometry for the very short period W Ursae Majoris binary V743 Sagittarii is presented. Four epochs of minimum light were determined from observations made during two primary and two secondary eclipses. Corrected values of four previous timings are also given. The period study yielded an improved ephemeris. However, a large (∼60,000 orbit) gap in the data precluded any definitive period analysis at this time. Standard magnitudes are reported. The light curves reveal that V743 Sgr is a G8-K0 spectral type W-type W UMa system with a 22 minute time of constant light in the primary minimum. The light curves have a prominent asymmetry occurring in the maximum at phase 0.25. It is 6% higher than the maximum at phase 0.75 in V magnitude. Our simultaneous light-curve solution yielded a component temperature difference of ∼350 K, a mass ratio of ∼0.31, and a fill-out of ∼10%. A large polar cool star spot was calculated. Apparently, the system has rapidly changing spot activity. This is indicated by a comparison of our previously published 1989 curves with the present 1991 curves, which show a shallower primary eclipse and a reversal in the sense of the asymmetry in the maxima (phase 0.75 higher).