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In this paper, we present the analysis of time-series observations from 2013and 2014 of five metal rich ([Fe/H] $>$ -1) globular clusters: NGC~6388,NGC~6441, NGC~6528, NGC~6638, and NGC~6652. The data have been used to performa census of the variable stars in the central parts of these clusters. Theobservations were made with the electron multiplying CCD (EMCCD) camera at theDanish 1.54m Telescope at La Silla, Chile, and they were analysed usingdifference image analysis (DIA) to obtain high-precision light curves of thevariable stars. It was possible to identify and classify all of the previouslyknown or suspected variable stars in the central regions of the five clusters.Furthermore, we were able to identify, and in most cases classify 48, 49, 7, 8,and 2 previously unknown variables in NGC~6388, NGC~6441, NGC~6528, NGC~6638,and NGC~6652, respectively. Especially interesting is the case of NGC~6441, forwhich the variable star population of about 150 stars has been thoroughlyexamined by previous studies, including a Hubble Space Telescope study. In thispaper we are able to present 49 new variable stars for this cluster, of whichone (possibly two) are RR Lyrae stars, two are W Virginis stars, and the restare long period semi-regular/irregular variables on the red giant branch. Wehave also detected the first double mode RR Lyrae in the cluster.

Searching for variable stars in the cores of five metal rich globular clusters using EMCCD observations