The Nainital-Cape Survey-IV

Abstract: The Nainital-Cape survey is a dedicated ongoing survey programme to search for and study pulsational variability in chemically peculiar (CP) stars to understand their internal structure and evolution. The main aims of this survey are to find new pulsating Ap and Am stars in the northern and southern hemisphere and to perform asteroseismic studies of these new pulsators. The survey is conducted using high-speed photometry. The candidate stars were selected on the basis of having Stromgren photometric indices similar to those of known pulsating CP stars. Over the last decade a total of 337 candidate pulsating CP stars were observed for the Nainital-Cape survey, making it one of the longest ground-based surveys for pulsation in CP stars in terms of time span and sample size. The previous papers of this series presented seven new pulsating variables and 229 null results. In this paper we present the light curves, frequency spectra and the various astrophysical parameters of the 108 additional CP stars observed since the last reported results. We have also tabulated the basic physical parameters of the known roAp stars. As part of establishing the detection limits in the Nainital-Cape survey, we investigated the scintillation noise level at the two observing sites used in this survey, Sutherland and Nainital, by comparing the combined frequency spectra stars observed from each location. Our analysis shows that both the sites permit the detection of variations on the order of 0.6 milli-magnitude (mmag) in the frequency range 1-4 mHz, with Sutherland being marginally better, on average.