The First Light Curve Solution of GW Leo and Refined Ephemeris of Two Contact Binary Systems

We performed the first light curve analysis of GW Leo and a new ephemeris is obtained for QT Boo. The light curve investigation also yields that the system GW Leo is a contact W UMa eclipsing binary with a photometric mass ratio of q = 0.44 ± 0.03, a fillout factor of f = 59.6%, and an inclination of 50.77° ± 0.09°. Due to the O'Connell effect which is known as asymmetries in the light curves' maxima, a cold spot is employed along with the solution. The photometric and physical parameters of GW Leo were determined (e.g., M_h = 1.373 ± 0.024, M_c = 0.604 ± 0.027, R_h = 1.261 ± 0.041, R_c = 0.909 ± 0.039, and a(${{R}_{ \odot }}$) = 2.553 ± 0.004). According to the light curve solution results, we suggest that GW Leo is an A-type W UMa binary system. We also calculate the distance of GW Leo from the distance modulus formula as 483.5 ± 41 pc, which is in a good agreement to the quantity measured by the Gaia EDR3 using the binary systems' parallax. Moreover, the positions of their components on the H-R diagram are represented.