Variables in the southern polar region evryscope 2016 data set

Abstract

The regions around the celestial poles offer the ability to find and characterize long-term variables from groundbased 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-learningbased 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 3σ limiting magnitude of g = 16 in dark time. In this study, covering all stars 9