Computer simulation experiment is very important in the phase of project design, the availability of simulated result highly depends on the scheme of error simulation. Time series observations are normally correlated....Computer simulation experiment is very important in the phase of project design, the availability of simulated result highly depends on the scheme of error simulation. Time series observations are normally correlated. This paper first discusses the formula of correlated error propagation, then derives the formula of simulating time series correlated errors. This formula is then used to simulate correlated ephemerides errors of CHAMP, then the ephemerides are used to recover the gravity vector at satellite altitude with finite differential formula. The formulae derived in this paper are verified with the difference between the recovered gravity vectors and the `true values’ which are directly computed with the same gravity model as that generating the ephemerides.展开更多
This study details an astrometric observation campaign of the Near-Earth Asteroid 1998 HH49,conducted with the aim of refining our understanding of its physical characteristics.Utilizing the 50 cm telescope located at...This study details an astrometric observation campaign of the Near-Earth Asteroid 1998 HH49,conducted with the aim of refining our understanding of its physical characteristics.Utilizing the 50 cm telescope located at the Wumingshan Mountain in Daocheng,Sichuan,images were obtained over four nights,from 2023 October 19 to October 22.These observations were processed using Astrometrica software,facilitating the precise determination of the asteroid's position.The observational results were compared with the ephemerides from three distinct sources to verify accuracy:the Jet Propulsion Laboratory(JPL)Horizons System,the Institut de Mécanique Céleste et de Calcul deséphémérides(IMCCE)Miriade,and the Near-Earth Objects Dynamic Site(NEODyS-2).When compared with the JPL ephemeris,a mean observed-minus-calculated(O-C)result of 0.″07 in the R.A.direction and-0.″35 in the decl.direction was yielded.Furthermore,the comparison with the IMCCE ephemeris yielded mean O-C results of 0.″08 in the R.A.direction and-0.″06 in the decl.direction.The comparison with the NEODyS-2 ephemeris yielded the mean O-C results of 0.″06 in R.A.and-0.″49 in decl.direction.The study's findings demonstrate a general consistency between the observed data and the ephemeris predictions,with minor discrepancies observed across the data sets.Notably,both the JPL and NEODyS-2 ephemerides show that the residuals in the decl.direction exceed those in the R.A.direction.The disparities may result from atmospheric differential color refraction,ephemeris discrepancies,observational errors,and other factors.Additionally,it is worth noting that further investigation is required due to the potential influence of additional factors.Overall,the Daocheng 50 cm Telescope exhibits the ability to conduct high-precision positional measurements.展开更多
对导航卫星历书问题进行了综合研究,并结合J_2项分析解,提出了两套新的历书参数拟合方法和用户算法,与正常算法不同的是:8参数历书拟合算法以(?)=-3/2J_2等(R_e^2)/(p^2)n cos i隐性直接代替历书参数Ω_1;在用户算法中对MEO卫星以ω_k=...对导航卫星历书问题进行了综合研究,并结合J_2项分析解,提出了两套新的历书参数拟合方法和用户算法,与正常算法不同的是:8参数历书拟合算法以(?)=-3/2J_2等(R_e^2)/(p^2)n cos i隐性直接代替历书参数Ω_1;在用户算法中对MEO卫星以ω_k=ω_0-ω_1·(Δt/2-t_k),对高轨卫星以ω_k=ω_0-ω_1·(Δt/2-t_k)/2修正历书参数ω_k,其中ω_1=(A_2)/(p^2)n(2-5/2sin^2 i).9参数历书拟合算法在8参数的基础上增加了一个历书参数(?)=(T_Err_n-T_Err_0)/Δt/α参数,在用户算法中以ω_k=ω_0-ω_1·(Δt/2-t_k),M_k=M_0+n·t_k-(?)·(Δt/2-t_k)修正ω_k和M_k.通过多组模拟轨道和IGS精密轨道的历书拟合实验,结果表明,新8参数历书拟合方法具有参数少、迭代收敛速度快、对MEO卫星拟合精度高等优点;新9参数历书拟合算法,迭代收敛快,拟合精度优于其他算法.展开更多
文摘Computer simulation experiment is very important in the phase of project design, the availability of simulated result highly depends on the scheme of error simulation. Time series observations are normally correlated. This paper first discusses the formula of correlated error propagation, then derives the formula of simulating time series correlated errors. This formula is then used to simulate correlated ephemerides errors of CHAMP, then the ephemerides are used to recover the gravity vector at satellite altitude with finite differential formula. The formulae derived in this paper are verified with the difference between the recovered gravity vectors and the `true values’ which are directly computed with the same gravity model as that generating the ephemerides.
基金funded by the National Key R&D Program of China(grant No.2022YFE0116800)the National Natural Science Foundation of China(NSFC,grant No.12173085)the West Light Foundation of The Chinese Academy of Sciences Key scientific research projects of colleges and universities in Henan Province(grant No.23B16001)。
文摘This study details an astrometric observation campaign of the Near-Earth Asteroid 1998 HH49,conducted with the aim of refining our understanding of its physical characteristics.Utilizing the 50 cm telescope located at the Wumingshan Mountain in Daocheng,Sichuan,images were obtained over four nights,from 2023 October 19 to October 22.These observations were processed using Astrometrica software,facilitating the precise determination of the asteroid's position.The observational results were compared with the ephemerides from three distinct sources to verify accuracy:the Jet Propulsion Laboratory(JPL)Horizons System,the Institut de Mécanique Céleste et de Calcul deséphémérides(IMCCE)Miriade,and the Near-Earth Objects Dynamic Site(NEODyS-2).When compared with the JPL ephemeris,a mean observed-minus-calculated(O-C)result of 0.″07 in the R.A.direction and-0.″35 in the decl.direction was yielded.Furthermore,the comparison with the IMCCE ephemeris yielded mean O-C results of 0.″08 in the R.A.direction and-0.″06 in the decl.direction.The comparison with the NEODyS-2 ephemeris yielded the mean O-C results of 0.″06 in R.A.and-0.″49 in decl.direction.The study's findings demonstrate a general consistency between the observed data and the ephemeris predictions,with minor discrepancies observed across the data sets.Notably,both the JPL and NEODyS-2 ephemerides show that the residuals in the decl.direction exceed those in the R.A.direction.The disparities may result from atmospheric differential color refraction,ephemeris discrepancies,observational errors,and other factors.Additionally,it is worth noting that further investigation is required due to the potential influence of additional factors.Overall,the Daocheng 50 cm Telescope exhibits the ability to conduct high-precision positional measurements.
文摘对导航卫星历书问题进行了综合研究,并结合J_2项分析解,提出了两套新的历书参数拟合方法和用户算法,与正常算法不同的是:8参数历书拟合算法以(?)=-3/2J_2等(R_e^2)/(p^2)n cos i隐性直接代替历书参数Ω_1;在用户算法中对MEO卫星以ω_k=ω_0-ω_1·(Δt/2-t_k),对高轨卫星以ω_k=ω_0-ω_1·(Δt/2-t_k)/2修正历书参数ω_k,其中ω_1=(A_2)/(p^2)n(2-5/2sin^2 i).9参数历书拟合算法在8参数的基础上增加了一个历书参数(?)=(T_Err_n-T_Err_0)/Δt/α参数,在用户算法中以ω_k=ω_0-ω_1·(Δt/2-t_k),M_k=M_0+n·t_k-(?)·(Δt/2-t_k)修正ω_k和M_k.通过多组模拟轨道和IGS精密轨道的历书拟合实验,结果表明,新8参数历书拟合方法具有参数少、迭代收敛速度快、对MEO卫星拟合精度高等优点;新9参数历书拟合算法,迭代收敛快,拟合精度优于其他算法.
文摘在详细介绍美国JPL(Jet Propulsion Laboratory,喷气推进实验室)发布的DE(Development Ephemerides,行星/月球展开历表)系列历表的基本情况、头文件和数据文件的结构、历表计算原理等内容的基础上,以DE405、DE421、DE431为例,分别计算了1900—2200年间月球、太阳、行星等天体在地心天球参考系中的坐标及速度,并由此得到3个历表间的差异,结果表明DE431与DE421之间的差异,整体而言要小于二者同DE405之间的差异。最后以引潮力的计算为例,表明历表更新对于引潮力的影响基本可忽略不计,验证了IERS(International Earth Rotation and reference systems Service,国际地球自转与参考系服务)规范中关于历表更新对相关地球科学影响十分有限的结论。
