Variables in 47 Tuc

The observations consisted of near-continuous 160 s exposures alternating between the F555W and F814W filters for 8.3 days in 1999 July with the Wide Field Planetary Camera 2 on the Hubble Space Telescope. Using Fourier and other search methods, 11 detached eclipsing binaries and 15 W Ursa Majoris stars have been discovered plus an additional 10 contact or near-contact noneclipsing systems.

After correction for nonuniform area coverage of the survey, the observed frequencies of detached eclipsing binaries and W UMa stars within 90" of the cluster center are 0.022% and 0.031%, respectively. The data were taken over an 8.3 day period, 1999 July 3-11, during which HST was pointed continuously at 47 Tuc.