  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 O'Connell 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.
