Volume 47 number 2 (2019)
CCD, BVRcIc light curves of OR Leo were taken on 21, 22, 24 January, 11, 25 February, and 11 March 2018 at Dark Sky Observatory in North Carolina with the 0.81-m reflector of Appalachian State University by D. Caton. OR Leo was discovered by the SAVS survey which classified it as a V = 0.51 amplitude, EW variable. Ten times of minimum light were calculated, five primary and five secondary eclipses, from our present observations. The following quadratic ephemeris was determined from all available times of minimum light. The 15-year (~20,000 orbits) period study shows that the orbital period is increasing at a very significant level of confidence: JD Hel Min I = 2458188.65373 (0.00039)d + 0.2709786(0.0000002) × E + 5.6(0.2) × 10^–10 × E2. The mass ratio is found to be somewhat extreme, M2 / M1 = 0.1827 ± 0.0004 (M1 / M2 = 5.5). The total eclipses assure this determination. Its Roche Lobe fill-out is ~24%. The solution had no need of spots. The temperature difference of the components is about ~ 60 K, with the more massive component the hotter one, so it is an A-type W UMa binary. The inclination is 81.1 ± 0.2°. The secondary eclipse shows a time of constant light with an eclipse duration of 27 minutes.