Presentation #215.05 in the session “Binary Stellar Systems I”.
CCD, BVRI light curves of V1302 Her were taken on 24, May, 07, and 23. 24, 27 June 2020 at the Dark Sky Observatory, North Carolina with the 32-inch reflector of Appalachian State University. The variability of V1302 Her (GSC 3101-0683) was discovered in the FOV of V338 Her by the ROTSE1 experiment (Akerlof 2000). Liakos (2009) reported a new period of Min. I = 2454610.3476169 + 0.3162897d*E for this W UMa variable. It is classified as a contact variable with a mean V magnitude of 11.77 and amplitude of V ~ 0.4. Twenty-four times of minimum light are found in the literature along with 3 visual timings. From our present observations, which include four primary eclipses and three secondary eclipses. From these we determined a linear and a quadratic ephemeris, JD Hel MinI = 2459027.65873 ± 0.00080d + 0.31629036 ± 0.00000072×E (1) JD Hel MinI = 2459027.66132 ± 0.00054d + 0.31629221 ± 0.00000017×E+ 0.000000000121 ± 0.000000000011×E2 (2) Thus, from our 16-year period study, the period is found to be increasing. This could be due to mass transfer making the mass ratio decrease (q = M2/M1, all pairs of values should be corrected with a Phase Shift of 0.5). A Wilson-Devinney analyses reveal that the system is an W-type (less massive component is the hottest) W UMa binary with a fairly extreme mass ratio, q = 0.2426 ± 0.0003, 1/q = M1/M2 = 4.1). Its Roche Lobe fill-out is ~23%. One hot spot was needed in the solution. The temperature difference of the components is only ~263 K, with the more massive component as the slightly cooler one. The inclination is high, 87.0 ± 0.2 resulting in a time of constant light in the primary eclipse. The eclipse duration is some 34 minutes. More information is given in this preliminary report.