Photomeric analysis of eclipsing binaries: VY UMI, RU UMI AND GSC 04364-00648

We present the photometric analysis of $\mathit{\text{BVR}}$ and $\mathit{\text{TESS}}$ light curves of three eclipsing binaries (RU~UMi and purely studied VY~UMi, GSC 04364-00648), together with their period changes considering archival data and new minima times from our and $\mathit{\text{TESS}}$ observations. For the first time we detected wave-like variations with low-amplitude in $O-C$ residua of RU UMi, which can be interpreted as a consequence of the light-time effect caused by the 3rd invisible component with period 7370 days. Period increase with rate 2.56(9)$\times {10}^{-7}$~d/yr${}^{-1}$ detected in the VY UMi system corresponds to mass transfer from the secondary to the primary component. For GSC 04364-00648 binary system we find some quadratic changes on the $O-C$ diagram, which corresponds to a period decrease with a high rate of $-2.26(5)\times {10}^{-5}$~d/yr${}^{-1}$. We cannot assumptions about their nature, mainly due to short time of observation and uneven coverage of $O-C$ diagram. We also determined the absolute parameter of their components using the photometric solution and $\mathit{\text{GAIA}}$ distances.