Photometric and spectral observations of the W UMa binaries FI Lyn, UV Lyn, and NSVS 781878 with periods of around 9.5–10 hr were carried out in order to determine their global parameters by simultaneous light curve and radial velocity curve solutions. We found that the three targets have shallow‐contact configurations with close in mass and radius components. UV Lyn is of W‐subtype, NSVS 781878 is of A‐subtype, while FI Lyn may be considered as binary in thermal contact. Our data show evidences of photospheric activity of the targets but not of emission in the H_α line. The surface inhomogeneity of UV Lyn is stable during the last several decades. Its O–C diagram implies presence of third body with a period of 24 years. The distances of FI Lyn, UV Lyn, and NSVS 781878 calculated from the derived luminosities coincide with those obtained by GAIA astrometrically.

中文翻译：

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W UMa星的全局参数为FI Lyn，UV Lyn和NSVS 781878

对W UMa双星FI Lyn，UV Lyn和NSVS 781878进行了约9.5-10小时的光度和光谱观测，以便通过同时的光曲线和径向速度曲线解确定它们的全局参数。我们发现这三个目标具有质量和半径分量均接近的浅接触配置。UV Lyn是W亚型的，NSVS 781878是A亚型的，而FI Lyn在热接触中可能被认为是二元的。我们的数据显示了目标的光球活动的证据，但在_Hα线中没有发射的证据。在过去的几十年中，UV Lyn的表面不均匀性是稳定的。其OC该图表示存在第三者的时间为24年。根据导出的光度计算出的FI Lyn，UV Lyn和NSVS 781878的距离与GAIA的天文测量相一致。