The paper presents the results of estimation of the precision of determining the Yarkovsky effect parameter А2 for asteroids with small perihelion distances known for January 2021. It is shown that the observation interval has a significant effect on the precision of the parameter А2. As the interval increases, the root-mean-square error of the parameter decreases. For asteroids (3200) Phaethon and (137924) 2000 BD19 with large arc lengths, an experiment was carried out to reduce the number of real observations. A decrease in the interval and number of observations leads to a loss in the precision of the determined parameter. Modeling of observations based on the real observations with an increase in their precision showed that the root-mean-square error of the parameter А2 decreases in proportion to the increase in the observation accuracy. The increase in the arc length due to the model observations confirmed the conclusion about the inverse dependence of the uncertainty of the parameter А2 on the interval and number of observations