The Periodicity of Residuals $\Delta_{\varphi}$ and $\Delta \theta$ of The Double Star ADS 11520

D. Olević, D. Djurović

The periodical variations of the residuals of radius $(O-C)_\varphi$ and positional angle $(O-C)_\theta$ of double star ADS 11520 was remarked. From the observations made in period 1990-1976 the corrections of Van den Bossś orbital elements are computed and it is shown that the periodical variations of residuals relative to the new orbital elements exist.