We performed the first light curve analysis of GW Leo and a new ephemeris is obtained for QT Boo. In the present photometric study of two contact binary systems, we found that the period of these binary systems is decreasing at a rate of dp/dt=-6.21*10^(-3) days yr^(-1) for GW Leo, and dp/dt=-4.72*10^(-3) days yr^(-1) for QT Boo, respectively. 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=0.881+-0.030, a fillout factor of f=3%, and an inclination of 54.060+-0.066 deg. Due to the OConnell effect which is known as asymmetries in the light curves maxima, a cold spot is employed along with the solution. We also calculate the distance of GW Leo from the distance modulus formula as 465.58+-23 pc, which is relatively close to the quantity measured by the Gaia DR2 using the binary systems parallax. Moreover, the positions of their components on the H-R diagram are represented.
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