Stellar surveys

Over the last decades, rapid advances in technology and the resulting increasing number of large-scale photometric and spectroscopic surveys have helped to propel astronomy into a new data-rich era. During the past few years, our working group has exploited the available wealth of data for the study of chemically peculiar (CP) stars of the upper main sequence. The main focus has been on the analysis of the Ap/CP2 stars and the He-peculiar stars, which are often grouped together under the term of magnetic CP (mCP) stars. Due to the influence of a strong and organized magnetic field on the diffusion processes, mCP stars show a non-uniform distribution of chemical elements (chemical spots or belts) on their surfaces. Flux is redistributed in these spots, which results in strictly periodic light and spectral variations with the rotation period, which are well understood in terms of the oblique-rotator model in which the magnetic axis is oblique to the rotation axis. According to convention, photometrically variable mCP stars are referred to as alpha2 Canum Venaticorum (ACV) variables. In this talk, we review the capabilities of the following ground-based photometric surveys: - All Sky Automated Survey (ASAS-3) - Asteroid Terrestrial-impact Last Alert System (ATLAS) - The Kilodegree Extremely Little Telescope (KELT) - The Multi-site All-Sky CAmeRA (MASCARA) - Wide Angle Search for Planets (WASP) - The Zwicky Transient Facility (ZTF) Our data archival techniques and time series analysis methods can be applied to any other group of OBA stars. We furthermore describe our data analysis techniques and time series analysis, which can be applied to any other group of OBA stars. We also detail our efforts at discovering and classifying new mCP stars in the spectroscopic archives of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) using an automated procedure (Richard O. Gray's MKCLASS code) and manual classification. This approach can also be applied to the whole group of OBA stars