1999A&A...348..789C

Time-series CCD photometry of the open cluster NGC 7654 was performed over five nights from October 2nd to 18th, 1997 U.T., in order to search for new variable stars. We also carried out UBV photometric observations to obtain physical parameters of variable stars in the cluster. We have derived the distance modulus of (V-M_V)_o=10.9±0.2 and the interstellar reddening of E(B-V)=0.62±0.05 by fitting the ZAMS to the observed color-color and color-magnitude diagrams of the cluster. Using the theoretical isochrones with solar metal abundance by Bertelli et al. (1994A&AS..106..275B), an age of the cluster, logt=8.0, was estimated. Applying the ensemble normalization technique to the observed 1215 time-series data, light variations of 284 stars, fainter than 11.0mag in the observed field, were carefully examined. As a result, three slowly pulsating B stars and one eclipsing binary were discovered in the cluster. We also confirmed the light variation of a low amplitude δ Sct star which has been recently discovered by Viskum et al. (1997A&A...328..158V).