Multi-color light curves and orbital period research of eclipsing binary V1073 Cyg

New multi-color BV R_cI_c photometric observations are presented for the W UMa type eclipsing binary V1073 Cyg. The multi-color light curve analysis with the Wilson-Devinney procedure yielded the absolute parameters of this system, showing that V1073 Cyg is a shallow contact binary system with a fill-out factor f = 0.124(±0.011). We collected all available times of light minima spanning 119 yr, including CCD data to construct the O − C curve, and performed detailed O − C analysis. The O − C diagram shows that the period change is complex. A long-term continuous decrease and a cyclic variation exist. The period is decreasing at a rate of Ṗ = −1.04(±0.18) × 10⁻¹⁰ d cycle⁻¹ and, with the period decrease, V1073 Cyg will evolve to the deep contact stage. The cyclic variation with a period of P ₃ = 82.7(±3.6) yr and an amplitude of A = 0.028(±0.002)d may be explained by magnetic activity of one or both components or the light travel time effect caused by a distant third companion with M ₃(i′ = 90°) = 0.511 M⊙. (paper)