Exoplanets in the Antarctic Sky. I. The First Data Release of AST3-II (CHESPA) and New Found Variables within the Southern CVZ of TESS

International audienceLocated at Dome A, the highest point of the Antarctic plateau, the ChineseKunlun station is considered to be one of the best ground-based photometricsites because of its extremely cold, dry, and stable atmosphere(Saunders et al.2009). A target can be monitored from there for over 40 days without diurnalinterruption during a polar winter. This makes Kunlun station a perfect site tosearch for short-period transiting exoplanets. Since 2008, an observatory hasbeen built at Kunlun station and three telescopes are working there. Usingthese telescopes, the AST3 project has been carried out over the last six yearswith a search for transiting exoplanets as one of its key programs (CHESPA). Inthe austral winters of 2016 and 2017, a set of target fields in the SouthernCVZ of TESS (Ricker et al. 2009) were monitored by the AST3-II telescope. Inthis paper, we introduce the CHESPA and present the first data releasecontaining photometry of 26,578 bright stars (m_i < 15). The best photometricprecision at the optimum magnitude for the survey is around 2 mmag. Todemonstrate the data quality, we also present a catalog of 221 variables with abrightness variation greater than 5 mmag from the 2016 data. Among thesevariables, 179 are newly identified periodic variables not listed in the AAVSOdatabasea), and 67 are listed in the Candidate Target List(Stassun et al.2017). These variables will require careful attention to avoid false-positivesignals when searching for transiting exoplanets. Dozens of new transitingexoplanet candidates will be also released in a subsequent paper(Zhang et al.2018b)