2023JAVSO..51...40S

CCD BVRI light curves of WISE J051352.5-170113 (GSC 5906 0087 = ASASSN-V J051352.59-170113.6) were taken on 21, 22, and 26, 27 January and 04 February 2021 at the Cerro Tololo InterAmerican Observatory, Chile, with the 0.6-m reflector, remotely. It is classified as a contact variable with a mean V magnitude of 11.77 and amplitude of V ∼ 0.4. Five times of minimum light were determined, with one from the literature, along with 7 times of low light. From our present observations, and one primary eclipse and four secondary eclipses, we determined linear and quadratic ephemerides. From our 20-year period study, the period is found to be increasing. This might be due to mass transfer to the more massive, primary component making the mass ratio more extreme (q = M<SUB>2</SUB>/ M<SUB>1</SUB>). A Wilson-Devinney Program analysis reveals that the system is a A-type (more massive component is the hottest) W UMa binary with a fairly extreme mass ratio, q = 0.2987 ± 0.0007, 1/ q = M<SUB>1</SUB>/ M<SUB>2</SUB> = 3.35). Its Roche Lobe fill-out is ∼ 18.9%. One hot spot was needed in the solution. The temperature difference of the components is only ∼ 32 K, making the system in good thermal contact. The inclination is high, 80°, resulting in a brief total secondary eclipse lasting about 15 minutes.