Ratzloff, Jeffrey K.Corbett, Henry T.Law, Nicholas M.Barlow, Brad N.Glazier, AmyHoward, Ward S.Fors Aldrich, OctaviSer Badia, Daniel delTrifonov, Trifon2024-02-092024-02-092019-08-010004-6280https://hdl.handle.net/2445/207408The regions around the celestial poles offer the ability to find and characterize long-term variables from ground-based observatories. We used multi-year Evryscope data to search for high-amplitude (≈5% or greater) variable objects among 160,000 bright stars (mv < 14.5) near the South Celestial Pole. We developed a machine-learning-based spectral classifier to identify eclipse and transit candidates with M-dwarf or K-dwarf host stars, and potential low-mass secondary stars or gas-giant planets. The large amplitude transit signals from low-mass companions of smaller dwarf host stars lessens the photometric precision and systematics removal requirements necessary for detection, and increases the discoveries from long-term observations with modest light-curve precision among the faintest stars in the survey. The Evryscope is a robotic telescope array that observes the Southern sky continuously at 2-minute cadence, searching for stellar variability, transients, transits around exotic stars and other observationally challenging astrophysical variables. The multi-year photometric stability is better than 1% for bright stars in uncrowded regions, with a 3<em>σ</em> limiting magnitude of g = 16 in dark time. In this study, covering all stars 9 < mv < 14.5, in declinations −75° to −90°, and searching for high-amplitude variability, we recover 346 known variables and discover 303 new variables, including 168 eclipsing binaries. We characterize the discoveries and provide the amplitudes, periods, and variability type. A 1.7 RJ planet candidate with a late K-dwarf primary was found and the transit signal was verified with the PROMPT telescope network. Further follow-up revealed this object to be a likely grazing eclipsing binary system with nearly identical primary and secondary K5 stars. Radial-velocity measurements from the Goodman Spectrograph on the 4.1 meter SOAR telescope of the likely lowest-mass targets reveal that six of the eclipsing binary discoveries are low-mass (.06–.37 <em>M</em>⊙) secondaries with K-dwarf primaries, strong candidates for precision mass–radius measurements.35 p.application/pdfeng(c) Ratzloff, Jeffrey K. et al., 2019PlanetesSatèl·litsRegions polarsPlanetsSatellitesPolar regionsinfo:eu-repo/semantics/article6947322024-02-09info:eu-repo/semantics/openAccess