小行星(99942)Apophis作为一个具有潜在威胁的近地小天体,自从被发现以来就倍受关注。Apophis飞掠地球期间,复杂的地月系统引力环境会对其轨道产生显著影响。本文首先分析了太阳系历表不确定度对Apophis轨道的影响,并利用2004-2021年期间的光学和雷达观测数据对Apophis的轨道和Yarkovsky效应参数A2进行了测定。结果表明2021年的观测数据显著地提高了Apophis轨道的确定精度和Yarkovsky效应的测量信噪比。2004-2022年期间的Apophis轨道误差小于10km(9σ),Yarkovsky效应参数的测定结果为公式(对应信噪比约为22.8)。
As a near Earth asteroid(NEA)having potential threat to impact the Earth,asteroid(99942)Apophis has been concerned widely since its discovery.During close encounters with the Earth,the orbit of Apophis is disturbed by the gravitational environment of the Earth-Moon system significantly.The author firstly analyzes the influences of the uncertainties of solar system ephemerides on the orbital motion of Apophis.The orbit of Apophis and Yarkovsky parameter A2 are determined with the optical and radar observations from 2004 to 2021.The result presents that adoption of the data observed in 2021 significantly improves the orbit precision of Apophis and the signal noise rate(SNR)of detecting of Yarkovsky effect.The orbit error of Apophis from 2004 to 2022 is smaller than 10km(9σ),and the measured Yarkovsky parameter A2=-2.73±0.12(the corresponding SNR ~22.8).
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