This study addresses the critical technical need to enhance the 1–10 day prediction accuracy of polar motion (PM)in satellite autonomous navigation and deep space exploration,with a focus on optimizing the convolutio...This study addresses the critical technical need to enhance the 1–10 day prediction accuracy of polar motion (PM)in satellite autonomous navigation and deep space exploration,with a focus on optimizing the convolution input accuracy within the least squares and autoregression with effective angular momentum (LS+AR+EAM) method.Through theoretical derivation and numerical experiments,we identify the significant impact of the iterative mechanism of the convolution input in the Liouville equation on PM prediction accuracy.On one hand,it clearly states that the initial step of convolution iteration should begin today using today’s daily data,rather than relying on the iterative convolution result from the previous step.On the other hand,due to the requirement for the previous PM,previous geodetic angular momentum (GAM),and current GAM in convolution input,several GAM predictions are constructed using IGS ultra-rapid 6 hr resolution data.Additionally,a hybrid method is used to obtain multiple EAM predictions.By integrating these predictions,the range of prediction errors is effectively constrained.The hindcast results,submitted before 20:00 UTC every Wednesday during the official interval of the second Earth Orientation Parameters Prediction Comparison Campaign (2nd EOP PCC),show that the proposed method improved the mean absolute error (MAE) over the first seven days compared to the first-place method(ID136),with improvements of 51.9%,32.0%,28.5%,20.9%,19.2%,17.2%,and 17.0%in the X direction,and20.6%,16.2%,14.4%,12.8%,8.7%,3.1%,and 3.0% in the Y direction.Furthermore,extending the statistical range from 2016/1/6 to 2022/12/28,the proposed method yields MAE values of (0.165,0.137),(0.735,0.505),and (1.874,1.238) mas for days 1,5,and 10,respectively,outperforming the official predictions by IERS or USNO,which are (0.255,0.194),(1.534,1.110),and (2.875,1.877) mas.This not only validates the stability of the proposed method but also demonstrates its direct applicability in real-world engineering applications.展开更多
The multi-color imaging sky survey conducted by the China Space Station Telescope(CSST)holds significant promise for advancing the development of the celestial reference frame.In this study,we focus on assessing the a...The multi-color imaging sky survey conducted by the China Space Station Telescope(CSST)holds significant promise for advancing the development of the celestial reference frame.In this study,we focus on assessing the astrometric performance of the CSST celestial reference frame(CSST-CRF)in extending the Gaia Celestial Reference Frame 3(Gaia-CRF3).First,the orientation precision of the CSST reference frame is evaluated using a simulated set of extragalactic sources with CSST g magnitudes ranging from 18 to 25 mag.The estimated orientation uncertainty caused by random error insignificantly affects the alignment between Gaia-CRF3 and the CSST-CRF.Then,the systematic effect of incomplete CSST sky coverage on the alignment between CSST-CRF and Gaia-CRF3 is discussed by analyzing the differences between the subset of Gaia-CRF3 in the CSST observation region(Gaia-CRF3′)and Gaia-CRF3 as a whole.Using the third International Celestial Reference Frame(ICRF3)S/X band as an intermediate reference frame,the orientation offset between Gaia-CRF3′and GaiaCRF3 is estimated to be 20μas.This offset is marginally larger than the orientation offset between Gaia-CRF3 and the ICRF3,approximately 15μas.The residual spin and glide rate of Gaia-CRF3′are derived from the proper motions,consistent with that of Gaia-CRF3 within the formal error.Finally,we explore the role of CSST in establishing a multi-band celestial reference frame by comparing its limiting magnitude and observation accuracy with existing catalogs in the infrared and ultraviolet bands.Thanks to its broad wavelength coverage and highprecision measurements,CSST is well-positioned to make significant contributions to the development of a multiband celestial reference frame.展开更多
基金supported by the Astrometric Reference Frame project (Grant No.JZZX-0102)the National Natural Science Foundation of China (NSFC,Grant Nos.12473069,12233010,and 12173070)the Natural Science Foundation of Shanghai (Grant No.24ZR1476800)。
文摘This study addresses the critical technical need to enhance the 1–10 day prediction accuracy of polar motion (PM)in satellite autonomous navigation and deep space exploration,with a focus on optimizing the convolution input accuracy within the least squares and autoregression with effective angular momentum (LS+AR+EAM) method.Through theoretical derivation and numerical experiments,we identify the significant impact of the iterative mechanism of the convolution input in the Liouville equation on PM prediction accuracy.On one hand,it clearly states that the initial step of convolution iteration should begin today using today’s daily data,rather than relying on the iterative convolution result from the previous step.On the other hand,due to the requirement for the previous PM,previous geodetic angular momentum (GAM),and current GAM in convolution input,several GAM predictions are constructed using IGS ultra-rapid 6 hr resolution data.Additionally,a hybrid method is used to obtain multiple EAM predictions.By integrating these predictions,the range of prediction errors is effectively constrained.The hindcast results,submitted before 20:00 UTC every Wednesday during the official interval of the second Earth Orientation Parameters Prediction Comparison Campaign (2nd EOP PCC),show that the proposed method improved the mean absolute error (MAE) over the first seven days compared to the first-place method(ID136),with improvements of 51.9%,32.0%,28.5%,20.9%,19.2%,17.2%,and 17.0%in the X direction,and20.6%,16.2%,14.4%,12.8%,8.7%,3.1%,and 3.0% in the Y direction.Furthermore,extending the statistical range from 2016/1/6 to 2022/12/28,the proposed method yields MAE values of (0.165,0.137),(0.735,0.505),and (1.874,1.238) mas for days 1,5,and 10,respectively,outperforming the official predictions by IERS or USNO,which are (0.255,0.194),(1.534,1.110),and (2.875,1.877) mas.This not only validates the stability of the proposed method but also demonstrates its direct applicability in real-world engineering applications.
基金funded by the science research grants from the China Manned Space Project with NO.CMS-CSST-2021-A11and NO.CMS-CSST-2021-B10the National Natural Science Foundation of China(NSFC)under grant No.12373074。
文摘The multi-color imaging sky survey conducted by the China Space Station Telescope(CSST)holds significant promise for advancing the development of the celestial reference frame.In this study,we focus on assessing the astrometric performance of the CSST celestial reference frame(CSST-CRF)in extending the Gaia Celestial Reference Frame 3(Gaia-CRF3).First,the orientation precision of the CSST reference frame is evaluated using a simulated set of extragalactic sources with CSST g magnitudes ranging from 18 to 25 mag.The estimated orientation uncertainty caused by random error insignificantly affects the alignment between Gaia-CRF3 and the CSST-CRF.Then,the systematic effect of incomplete CSST sky coverage on the alignment between CSST-CRF and Gaia-CRF3 is discussed by analyzing the differences between the subset of Gaia-CRF3 in the CSST observation region(Gaia-CRF3′)and Gaia-CRF3 as a whole.Using the third International Celestial Reference Frame(ICRF3)S/X band as an intermediate reference frame,the orientation offset between Gaia-CRF3′and GaiaCRF3 is estimated to be 20μas.This offset is marginally larger than the orientation offset between Gaia-CRF3 and the ICRF3,approximately 15μas.The residual spin and glide rate of Gaia-CRF3′are derived from the proper motions,consistent with that of Gaia-CRF3 within the formal error.Finally,we explore the role of CSST in establishing a multi-band celestial reference frame by comparing its limiting magnitude and observation accuracy with existing catalogs in the infrared and ultraviolet bands.Thanks to its broad wavelength coverage and highprecision measurements,CSST is well-positioned to make significant contributions to the development of a multiband celestial reference frame.
