Three Periods in Asteroid 4197 Brightness Variations

In 1996, photometric observations of the near-Earth asteroid NEA 4197 (1982 TA) were performed at the Crimean Astrophysical Observatory. More than 2000 brightness measurements in the V band were made. The harmonic data analysis at a fairly high significance level revealed two close periods, P ₁= 3^h _.5372 ± 0^h _.0005 (amplitude 0 ^m _.4) and P ₂= 4^h _.367 ± 0^h _.001 (amplitude 0 ^m _.2). The third period, P ₃= 20^h _.26 ± 0^h _.05 (amplitude about 0 ^m _.15), was found at a lower significance level. The conclusion was drawn that the asteroid is a binary system. Its components rotate with the periods P ₁and P ₂, and P ₃is probably related to the orbital motion of the components. Assuming that the diameters of both components are equal to 2 km, the orbital radius equals 4.4 km.