On the correctness of orbital solutions obtained from a small set of points. Orbit of HIP 53731

HIP 53731 is a binary consisting of stars of the spectral types K0 and K9. Orbit of this object was constructed previously by Cvetkovi'c et al. (2016) and improved by Tokovinin (2019). It should be noted that there is an 180 degree ambiguity in the position angles of some published measurements. Speckle interferometric observations were obtained in 2007-2020 (21 measurements) at the 6-m telescope of the SAO RAS (BTA) by the authors of this article. The analysis of new data together with previously published ones made it possible to construct the accurate orbit of HIP 53731 and to halve the already known values of the orbital period of the system. As a result of the study, the mass sum, the masses of each component and their spectral types were determined by two independent methods. According to the qualitative classification of orbits, the orbital solution has grade 2 - "good" (observations cover more than half of the orbital period and correspond to different phases).