Photometric study of the contact binary 07g-3-00820 at the period cut off

07g-3-00820 is a K-type contact binary system with a period of 0.2269551 days. This extremely short period makes this system a rare target whose period is close to the empirical limit (0.22 days). R_c and I_c light curves of this binary were obtained using the 1.0 m reflecting telescope at Weihai Observatory of Shandong University. A high mass ratio of q = 1.300 ± 0.006 and a low contact degree of f = 5 % ± 1.5 % were determined from a photometric study using the Wilson-Devinney method. The following parameters of this W-subtype shallow contact system were derived: M₁ = 0.621 ± 0.072M_⊙ , M₂ = 0.807 ± 0.093M_⊙ , R₁ = 0.634 ± 0.036R_⊙ , R₂ = 0.710 ± 0.037R_⊙ , L₁ = 0.270 ± 0.037L_⊙ , and L₂ = 0.339 ± 0.048L_⊙ . By analyzing the location of the two components on the mass-luminosity diagram, we provide a preliminary discussion on the properties and the state of evolution of this system.