Search for second overtone Cepheids in the Magellanic Clouds. I. Study of three candidates in the SMC

Accurate CCD observations of three Cepheids in the SMC were made with the purpose of confirming their nature of second overtone mode Cepheids. The stars were suspected pulsating in the second overtone mode owing to the unusual light curve and short period reported by Payne-Gaposchkin & Gaposchkin (1966). The analysis of the new data shows that for two stars the previous periods are wrong, and in the three cases the new light curves are normal. According to the new observations, HV 1353 is a fundamental mode pulsator with small amplitude, and HV 1777 and HV 1779 are first overtone mode pulsators. Also the star HV 1763, whose nature was unknown, was observed in the field of HV 1777. The new data show that it is a first overtone mode Cepheid with P=2.117d.