Detection and study of variable sources with wide field imagers

摘要

In recent years massive CCD photometry has dramatically increased the number of known variable stars in the Milky Way and nearby galaxies of the Local Group. Some surveys are related to microlensing studies, distance determinations and the study of Cepheids and other pulsating stars, and are based on relatively small telescopes. The comparison of the performances of the various instruments shows the present limitations of the variable star research, and the requirements are to increase the sensitivity, spatial resolution and field of view. In order to get a better sensitivity, we adopted the W h-photometry, or unfiltered observations. We discuss the merits and defects of this technique in the context of recent studies with the ESO 0.9 m Dutch telescope and Wide Field Imager at the 2.2 m telescope. As regards the high precision photometry, we remark that a better very small amplitude variations with good confidence.