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E. Sandquist (San Diego State U.), M. Shetrone (U. Texas/McDonald Obs.)
We present an analysis of over 1200 images taken on 10 nights at the Mt. Laguna 1 m telescope of the open cluster M67. Our observations overlap with but extend beyond the field analyzed by Gilliland et al. (1991). The large number of stars on the frames has allowed us to obtain relative photometry of millimagnitude accuracy for many of the stars. We have discovered two new photometric variables: S 757 (a W UMa variable with P \approx 0.4 d) and S 1016 (a red giant having at least one total eclipse of depth 0.03 mag and long-period variation of P \approx 40 d and amplitude 0.04 mag). We confirm that S 1063 (a binary with P = 18.39 d, and cluster member with photometry placing it below the subgiant branch and to the red of the main sequence) is variable with an amplitude of 0.14 mag and period near the binary period. We also present a full light curve for the very unusual partial-eclipsing blue straggler S 1082 (P = 1.0677 d; Goranskij et al. 1992), showing significant variations on timescales of a month and shorter. In addition, our extensive observations of the W UMa variables S 1036 and S 1282 (AH Cnc) reveal significant variations in their light curves from night to night.
The author(s) of this abstract have provided an email address for comments about the abstract: erics@mintaka.sdsu.edu