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Journal articles on the topic 'Ephemric'

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Published: 4 June 2021
Last updated: 17 February 2022

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1

Skokić, Ivica, and Roman Brajša. "ALMA SOLAR EPHEMERIS GENERATOR." Rudarsko-geološko-naftni zbornik 34, no. 2 (2019): 59–65. http://dx.doi.org/10.17794/rgn.2019.2.7.

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2

Jia, Rui Xi, Xiao Yu Li, Chang Feng Xia, and Dong Yang Jin. "Broadcast Ephemeris Accuracy Analysis for GPS Based on Precise Ephemeris." Applied Mechanics and Materials 602-605 (August 2014): 3667–70. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.3667.

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The accuracy of broadcast ephemeris is an important index of a satellite navigation system. The theory and method of precise ephemeris assessing broadcast ephemeris are introduced. The accuracy of GPS satellite broadcast ephemeris is assessed with the precise ones provided by IGS. The orbital coordinates of GPS broadcast ephemeris from 18th to 24th October 2013 are calculated. The analysis shows that during this time the GPS satellite broadcast ephemeris is reliable, accurate and safe as the whole, meanwhile the broadcast ephemeris accuracy is about 1 meter, better than nominal accuracy of 5 meters.
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3

KENNEY, RICHARD. "EPHEMERIS." Yale Review 94, no. 3 (July 2006): 125–26. http://dx.doi.org/10.1111/j.1467-9736.2006.00217.x.

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4

Greenhouse, Stuart. "Ephemeris." Massachusetts Review 59, no. 3 (2018): 536–37. http://dx.doi.org/10.1353/mar.2018.0080.

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5

Yaqin, Alamul. "SOLAR EPHEMERIS ACCORDING TO SIMON NEWCOMB." Al-Hilal: Journal of Islamic Astronomy 2, no. 2 (April 30, 2021): 287–305. http://dx.doi.org/10.21580/al-hilal.2020.2.2.6724.

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The development of Falak cannot be separated from the ephemeris table, one of them i.e Simon Newcomb solar ephemeris. This ephemeris was used in the initial calculation of Abdur Rachim, one of Falak Indonesia's experts. The purpose of this study was to determine the accuracy of the Simon Newcomb ephemeris reckoning algorithm and its strengths and weaknesses. This paper use descriptive analysis as the research methodology. The results of this study are this Ephemeris is quite accurate because because there aremany correction terms and consider aspects of the planet's relative motion to the Earth that can be seen in the formula for perturbation and nutation correction. The advantage of this ephemeris,it has a long period correction which is useful for calculating the Sun ephemeris in years far enough from the epoch used and directly uses UT time in its calculations so there is no need to convert UT to TD. The weakness of this ephemeris is that it cannot be done manually because the formula used is too long and there are many formula corrections.
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Eroshkin, G. I., N. I. Glebova, M. A. Fursenko, and A. A. Trubitsina. "Some Aspects of Constructing Long Ephemerides of the Sun, Major Planets and the Moon: Ephemeris AE95." International Astronomical Union Colloquium 165 (1997): 245–50. http://dx.doi.org/10.1017/s0252921100046625.

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The construction of long-term numerical ephemerides of the Sun, major planets and the Moon is based essentially on the high-precision numerical solution of the problem of the motion of these bodies and polynomial representation of the data. The basis of each ephemeris is a mathematical model describing all the main features of the motions of the Sun, major planets, and Moon. Such mathematical model was first formulated for the ephemerides DE/LE and was widely applied with some variations for several national ephemeris construction. The model of the AE95 ephemeris is based on the DE200/LE200 ephemeris mathematical model. Being an ephemeris of a specific character, the AE95 ephemeris is a basis for a special edition “Supplement to the Astronomical Yearbook for 1996–2000”, issued by the Institute of the Theoretical Astronomy (ITA) (Glebova et al., 1995). This ephemeris covering the years 1960–2010 is not a long ephemeris in itself but the main principles of its construction allow one to elaborate the long-term ephemeris on an IBM PC-compatible computer. A high-precision long-term numerical integration of the motion of major bodies of the Solar System demands a choice of convenient variables and a high-precision method of the numerical integration, taking into consideration the specific features of both the problem to be solved and the computer to be utilized.
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Zhao, Rui Bin, Bo Shao, Rui Li, and Zhi Gang Huang. "A Satellite Ephemeris Correction Calculating Algorithm Based on the Hill Differential Equation." Applied Mechanics and Materials 336-338 (July 2013): 1682–87. http://dx.doi.org/10.4028/www.scientific.net/amm.336-338.1682.

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The Hill differential equation is used to describe the change characteristic of the ephemeris prediction error in order to calculate the satellite broadcast ephemeris error and the error change rate. After the ECEF coordinate system converses the satellite inertial coordinate system, both the satellite ephemeris correction and the correction accuracy can be calculated by the Kalman filter. When the GEO, IGSO and MEO satellites move over the China, the calculation algorithms based on the weighted least square, the velocity model of the Kalman filter and the Hill differential equation are compared in the computing performance of the ephemeris corrections by using the reference date of IGS website. The simulation results show that: the ephemeris correction solver value based on the Hill differential equation can accurately reflect the ephemeris error characteristics at the current time. And it is able to correctly reflect the perturbation impact for the satellite ephemeris error. The Hill differential equation method is more suitable at the master station for engineering application about the MEO, IGSO and GEO satellites.
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8

Ma, Xin, Jiancheng Fang, Xiaolin Ning, Gang Liu, and Hui Ye. "A Radio/Optical Integrated Navigation Method Based on Ephemeris Correction for an Interplanetary Probe to approach a Target Planet." Journal of Navigation 69, no. 3 (November 24, 2015): 613–38. http://dx.doi.org/10.1017/s0373463315000818.

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To obtain accurate navigation results with respect to Earth simultaneously with those with respect to the target for an interplanetary probe to approach the target planet, this paper proposes a Radio/Optical integrated navigation method based on ephemeris correction, which deeply affects the fusion accuracy. In this paper, the model of the ephemeris error is established, and taking the analytical solution of the ephemeris uncertainty as measurement, the target ephemeris error and its covariance are estimated by Kalman filter and fed back to modify the force models. By correcting the target ephemeris and using information fusion, the Radio/Optical integrated navigation prevents the ephemeris uncertainty polluting the fusion accuracy, and efficiently combines the radio and optical navigation results. The results show the influence of the ephemeris error can be removed, and the Radio/Optical integrated navigation is capable of providing accurate navigation results with respect to Earth and the target. The results demonstrate the proposed method yields an accuracy superior to the conventional method, which proves its effectiveness.
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9

Ning, Xiaolin, Zhuo Li, Yuqing Yang, Jiancheng Fang, and Gang Liu. "Analysis of Ephemeris Errors in Autonomous Celestial Navigation during Mars Approach Phase." Journal of Navigation 70, no. 3 (November 21, 2016): 505–26. http://dx.doi.org/10.1017/s0373463316000734.

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A Celestial Navigation System (CNS) is a feasible and economical autonomous navigation system for deep-space probes. Ephemeris errors have a great influence on the performance of CNSs during the Mars approach phase, but there are few research studies on this problem. In this paper, the analysis shows that the ephemeris error of Mars is slowly-varying, while the ephemeris error of Phobos and Deimos is periodical. The influence of the ephemeris errors of Mars and its satellites is analysed in relation to both the Sun-centred frame and the Mars-centred frame. The simulations show that the position error of a probe relative to the Sun caused by the Mars ephemeris error is almost equal to the ephemeris error itself, that the velocity error is affected slightly, and that the position and velocity relative to Mars are hardly affected. The navigation result of a Mars probe is also greatly affected by the quantities and periodicities of the ephemeris errors of Phobos and Deimos, especially that of Deimos.
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10

Xie, Shao Feng, Peng Fei Zhang, and Li Long Liu. "Analyzing the Precision of Chebyshev Polynomial Fitting GPS Satellite Ephemeris." Applied Mechanics and Materials 353-356 (August 2013): 3410–13. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.3410.

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Using Chebyshev polynomial to fit precise ephemeris of GPS, the nodes selection has a certain influence on the precision. In this paper we use 3 kinds of precise ephemeris ( IGF, IGR, IGU ) to analyze the difference precision of randomly selected interpolation node and Chebyshev points fitting orbit and compare the difference and precision of fitting orbit by 3 kinds of ephemeris and orbit provided by IGS. The result shows that using Chebyshev points to fit precise ephemeris, the precision of IGF and IGR can achieve mm levels, the precision of IGU can achieve cm levels.
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11

Fukushima, Toshio. "Time Ephemeris." Highlights of Astronomy 10 (1995): 256–57. http://dx.doi.org/10.1017/s1539299600011163.

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The location-independent part of TCB–TCG, the difference between the two new time scales adopted by the IAU (1992), was integrated numerically for three JPL planetary/lunar ephemerides; DE102, DE200, and DE245. The differences among these three integrations were mostly explained by the difference in the adopted constants of the ephemerides. It was shown that the post-Newtonian correction and the perturbation by asteroids are negligible except for the mean rate, LC The comparison of these numerical integrations with the analytical formulas of Hirayama et al. (1987) and Fairhead and Bretagnon (1990) as well as their extended versions lead to the best estimate of LC asCombining this with the recent value of the geoid potential in Bursa et al. (1992), we estimated the value of LB, the scale difference between TCB and TT, as
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12

Choi, Jin Haeng, Gimin Kim, Deok Won Lim, and Chandeok Park. "Study on Optimal Broadcast Ephemeris Parameters for GEO/IGSO Navigation Satellites." Sensors 20, no. 22 (November 16, 2020): 6544. http://dx.doi.org/10.3390/s20226544.

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This paper proposes new sets of suitable broadcast ephemeris parameters for geosynchronous (GEO) and inclined geosynchronous (IGSO) navigation satellites (NSs). Despite the increasing number of GEO and IGSO NSs, global positioning system (GPS)-type ephemeris parameters are still widely used for them. In an effort to provide higher fit accuracy, we analyze a variety of broadcast ephemeris parameters for GEO and IGSO satellites along with their orbital characteristics and propose optimal sets of parameters. Nonsingular elements and orbital plane rotation are adopted for alleviating/avoiding the singularity issues of GEO satellites. On the basis of 16 parameters of GPS LNAV, we add one to four parameters out of 28 correction ones to determine optimal sets of ephemeris parameters providing higher accuracy. All possible parameter sets are tested with the least-square curve fit for four BeiDou GEOs and six BeiDou IGSOs. Their fit accuracies are compared to determine the optimal broadcast ephemeris parameters that provide minimum fit errors. The set of optimal ephemeris parameters depends on the type of orbit. User range error (URE) accuracies of the proposed optimal ephemeris parameters ensure results within 2.4 cm for IGSO and 3.8 cm for GEO NSs. Moreover, the experimental results present common parameter sets for both IGSO and GEO for compatibility and uniformity. Compared with four conventional/well-known sets of ephemeris parameters for BeiDou, our proposed parameters can enhance accuracies of up to 34.5% in terms of URE. We also apply the proposed optimal parameter sets to one GEO and three IGSO satellites of QZSS. The effects of fitting intervals, number of parameters, total bits, and orbit types on the fit accuracy are addressed in detail.
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13

Akbar, Reza. "PERHITUNGAN DATA EPHEMERIS KOORDINAT MATAHARI MENGGUNAKAN ALGORITMA JEAN MEEUS HIGHER ACCURACY DAN KETERKAITANNYA DENGAN PENGEMBANGAN ILMU FALAK." Jurnal Ilmiah Islam Futura 16, no. 2 (July 18, 2017): 166. http://dx.doi.org/10.22373/jiif.v16i2.1509.

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Data of solar coordinate such as longitude and latitude of the ecliptic, declination, and right ascension are the data that are often involved in astronomical reckoning and practical islamic astronomy. These data are often found in ephemeris tables such as the ephemeris of Hisab Rukyat by Ministry of Religious Affairs of the Republic of Indonesia, Nautica Almanac and others. One of the algorithms used in the preparation of ephemeris data tables is the Jean Meeus Higher Accuracy algorithm. Calculation of ephemeris data of solar coordinates using these algorithms starts with counting Julian Day (JD) and Julian Day Ephemeris (JDE). By using advanced algorithms based on VSOP87 theory, we can then calculate the longitude and latitude of the solar ecliptic, the distance of the earth to the Sun, the true obliquity (angle between the celestial equator and the ecliptic), the right ascension and declination, the equation of time and the Sun's semi diameter. The calculation of the solar coordinate in this paper is for June 7, 2017 at 19.00 WIB or 12.00 GMT. The results will then be compared with the data of solar coordinate in Ephemeris Hisab Rukyat 2017 at the same time.
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14

Fukushima, Toshio, George H. Kaplan, George A. Krasinsky, Jean Eudes Arlot, John A. Bangert, Catherine Y. Hohenkerk, George A. Krasinsky, et al. "COMMISSION 4: EPHEMERIDES." Proceedings of the International Astronomical Union 4, T27A (December 2008): 5–11. http://dx.doi.org/10.1017/s1743921308025234.

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JPL planetary ephemeris development has been very active assimilating measurements from current planetary missions and supporting future missions. The NASA Mars Science Laboratory (MSL) mission with launch in 2009 requires knowledge of the Earth and Mars ephemerides with 30m accuracy. By comparison, the accuracy of the Mars ephemeris in the widely used DE405 ephemeris was about 3 km. Meeting the MSL needs requires an ongoing program of range and very-long baseline interferometry measurements of Mars orbiting spacecraft. The JPL ephemeris DE421 was released three months before the landing of the Phoenix mission on Mars, and has met the 300m requirement. Continued measurements are planned to support the MSL landing.
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15

Zhilinskiy, V. O., D. S. Pecheritsa, and L. G. Gagarina. "Analysis of Influence of Ephemeris-Time Information on Accuracy of Solving a Navigation Problem by Signals of GLONASS System." Proceedings of Universities. Electronics 25, no. 5 (October 2020): 465–74. http://dx.doi.org/10.24151/1561-5405-2020-25-5-465-474.

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The Global Navigation Satellite System has a huge impact on both the public and private sectors, including the social-economic development, it has many applications and is an integral part of many domains. The application of the satellite navigation systems remains the most relevant in the field of transport, including land, air and maritime transport. The GLONASS system consists of three segments and the operation of the entire system depends on functioning of each component, but primarily, the accuracy of measurements depends on the basis forming of the control segment and management, responsible for forming ephemeris-time information. In the work, the influence of ephemeris-time information on the accuracy of solving the navigation problem by the signals of the GLONASS satellite navigation system has been analyzed. The influence of both ephemeris information and the frequency information, and of the time corrections has been individually studied. The accuracy of the ephemeris-time information is especially important when solving the navigation problem by highly precise positioning method. For the analysis the following scenarios of the navigation problem solving have been formed: using high-precision and broadcast ephemeris-time information, a combination of broadcast (high-precision) ephemeris-time information, and high-precision (broadcast) satellite clock offsets and two scenarios with simulation of the calculation of the relative correction to the radio signal carrier frequency. Based on the study results it has been concluded that the contribution of the frequency-time corrections to the error of location determination is of the greatest importance and a huge impact on the error location, while the errors of the ephemeris information are insignificant
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Li, Dehai, Wei Yan, Jinzhong Mi, Yamin Dang, Yunbin Yuan, and Xingli Gan. "A Smart Realtime Service to Broadcast the Precise Orbits of GPS Satellite and Its Performance on Precise Point Positioning." Sensors 20, no. 11 (June 8, 2020): 3276. http://dx.doi.org/10.3390/s20113276.

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At present, Global Position System (GPS) navigation ephemeris mainly broadcasts satellite orbits with meter-level precision for standard point positioning and precise relative positioning. With the rapid development of real-time precise point positioning (PPP), the receiver or smartphone has begun to demand more and more convenient, continuous, and reliable access to real-time services of precise orbits. Therefore, this study proposes a solution of utilizing the 18-parameter ephemeris to directly broadcast ultra-rapid precise predicted orbits with centimeter-level precision for real-time PPP. For the first time in GPS, the difference in the PPP results between the precise orbits and the calculated orbits broadcasted from the generated ephemeris parameters is supplied as follows: (1) During the validity period of 2 h, root mean square (RMS) of the relative distance offsets between the results of PPP with the precise orbits and the results of PPP the 18-parameter ephemeris is only 0.0098 m. (2) Within 15 min after the validity period of 2 h, RMS of the relative distance offsets between the results of PPP with the precise orbits and the results of PPP with the predicted orbits by 18-parameter ephemeris is only 0.0057 m. Consequently, the 18-parameter ephemeris is feasible and advisable to broadcast precise predicted orbits for real-time PPP applications. Compared with the classic precise orbits broadcast mode with the orbit corrections defined by the radio technical commission for maritime services standards 10403.2 (RTCM), the mode of broadcasting the precise orbits with the 18-parameter ephemeris achieved the following improvements in convenience, continuity, and reliability: (1) The calculation of satellite position is the same as that of the navigation ephemeris excluding the additional correction operations required to the RTCM; (2) the amount of broadcast parameters was reduced by 20 times; (3) the length of the validity period was expanded 120 times, where the longer valid period helped to overcome the orbit corrections loss caused by RTCM stream failures; and (4) within 15 min after the validity period, the predicted orbits with an accuracy of 2 cm could still be provided by the 18-parameter ephemeris, which can ensure the real-time services of precise orbits in the case of a 15 min communication interruption of the RTCM orbit correction data stream.
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17

Lihua, Ma, and Meng Wang. "Influence of Ephemeris Error on GPS Single Point Positioning Accuracy." Artificial Satellites 48, no. 3 (September 1, 2013): 125–39. http://dx.doi.org/10.2478/arsa-2013-0011.

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Abstract The Global Positioning System (GPS) user makes use of the navigation message transmitted from GPS satellites to achieve its location. Because the receiver uses the satellite's location in position calculations, an ephemeris error, a difference between the expected and actual orbital position of a GPS satellite, reduces user accuracy. The influence extent is decided by the precision of broadcast ephemeris from the control station upload. Simulation analysis with the Yuma almanac show that maximum positioning error exists in the case where the ephemeris error is along the line-of-sight (LOS) direction. Meanwhile, the error is dependent on the relationship between the observer and spatial constellation at some time period.
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18

Robustelli, Umberto, Guido Benassai, and Giovanni Pugliano. "Signal in Space Error and Ephemeris Validity Time Evaluation of Milena and Doresa Galileo Satellites." Sensors 19, no. 8 (April 14, 2019): 1786. http://dx.doi.org/10.3390/s19081786.

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In August 2016, Milena (E14) and Doresa (E18) satellites started to broadcast ephemeris in navigation message for testing purposes. If these satellites could be used, an improvement in the position accuracy would be achieved. A small error in the ephemeris would impact the accuracy of positioning up to ±2.5 m, thus orbit error must be assessed. The ephemeris quality was evaluated by calculating the SISEorbit (in orbit Signal In Space Error) using six different ephemeris validity time thresholds (14,400 s, 10,800 s, 7200 s, 3600 s, 1800 s, and 900 s). Two different periods of 2018 were analyzed by using IGS products: DOYs 52–71 and DOYs 172–191. For the first period, two different types of ephemeris were used: those received in IGS YEL2 station and the BRDM ones. Milena (E14) and Doresa (E18) satellites show a higher SISEorbit than the others. If validity time is reduced, the SISEorbit RMS of Milena (E14) and Doresa (E18) greatly decreases differently from the other satellites, for which the improvement, although present, is small. Milena (E14) and Doresa (E18) reach a SISEorbit RMS of about 1 m (comparable to that of the other Galileo satellites reach with the nominal validity time) when validity time of 1800 s is used. Therefore, using this threshold, the two satellites could be used to improve single point positioning accuracy.
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19

Capitaine, Nicole. "Definition of the Celestial Ephemeris Pole and the Celestial Ephemeris Origin." International Astronomical Union Colloquium 180 (March 2000): 153–63. http://dx.doi.org/10.1017/s0252921100000245.

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AbstractThe adoption of the International Celestial Reference System (ICRS) by the IAU in use since 1 January 1998, and the accuracy achieved by the most recent models and observations of Earth rotation call for a redefinition of the Earth Orientation Parameters (EOP). First, the precession-nutation parameters and Greenwich sidereal time, which are currently defined in the FK5 System, have to be re-defined to be consistent with the ICRS. Second, the current definition of the Celestial Ephemeris Pole (CEP) has to be extended in order to be consistent with the most recent models for nutation and polar motion at a microarsecond accuracy including diurnal and sub-diurnal components, as well as with new strategies of observations. Such issues have been under consideration by the subgroup T5 named “Computational Consequences” of the IAU Working Group “ICRS”. This paper gives, as the basis for future recommendations, the preliminary proposals of the subgroup T5 for a modern definition of the CEP, for the definition of more basic EOP in the ICRS and for the choice of a new origin on the equator of the CEP in place of the equinox. Then, the paper emphasizes the use of the Celestial Ephemeris Origin (CEO) which is defined as the “non-rotating origin” in the celestial frame on the equator of the CEP.
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Yousif, Hamad, and Ahmed El-Rabbany. "Assessment of Several Interpolation Methods for Precise GPS Orbit." Journal of Navigation 60, no. 3 (August 9, 2007): 443–55. http://dx.doi.org/10.1017/s0373463307004250.

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GPS applications such as Precise Point Positioning (PPP) require the availability of precise ephemeris at high rate. To support these applications, several institutions such as the International GNSS Service (IGS) have developed precise orbital service. Unfortunately, however, the data rate of such precise orbits is usually limited to 15 minutes. To overcome this problem, a number of orbital interpolation methods are proposed. This paper examines the performance of four interpolation methods for IGS precise GPS orbits, namely Lagrange, Newton Divided Difference, Cubic Spline and Trigonometric interpolation. In addition, the paper discusses a new approach, which utilizes the residuals between the broadcast and precise ephemeris to generate a high density precise ephemeris. It is shown that the new approach produces better results than previously reported orbital interpolation accuracy.
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21

Pashkevich, V. V. "RERS2013: A New High-precision Rigid Earth Rotation Series." Artificial Satellites 49, no. 3 (September 1, 2014): 161–77. http://dx.doi.org/10.2478/arsa-2014-0013.

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Abstract In the previous investigation (Pashkevich, 2013) the high-precision Rigid Earth Rotation Series (designated RERS2012) dynamically adequate to the JPL DE406/LE406 (Standish, 1998) ephemeris over 2000 and 6000 years were constructed. The main aim of present research is improvement of the Rigid Earth Rotation Series RERS2012 by using the JPL DE422/LE422 (Folkner, 2011) ephemeris, and as a result is produced construction of the new high-precision Rigid Earth Rotation Series dynamically adequate to the JPL DE422/LE422 ephemeris over 2000 and 6000 years. The discrepancies in Euler angles between the high-precision numerical solutions and the semi-analytical solutions of the rigid Earth rotation problem are investigated by least squares and spectral analysis methods using the iterative algorithm (Pashkevich, 2013). In order to demonstrate the good convergence of this iterative algorithm are constructed additional solutions of the rigid Earth rotation dynamically adequate to the JPL DE422/LE422 over 2000 years by improvement solutions SMART97 (Bretagnon et al., 1998) and S9000 (Pashkevich and Eroshkin, 2005a). As the results of this investigation, the new improved high-precision Rigid Earth Rotation Series RERS2013 dynamically adequate to the DE422/LE422 ephemeris over 2000 and 6000 years have been constructed. The discrepancies in Euler angles between the numerical solution and RERS2013 do not surpass: 4 uas over 2000 years, 1 mas over 6000 years. The RERS2013 series is more accurate than the RERS2012 series, which is dynamically adequate to the DE406/LE406 ephemeris. The good convergence of the iterative algorithm of this study has been confirmed.
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Tran, Dinh Trong, Dinh Huy Nguyen, Ngoc Dung Luong, and Duy Toan Dao. "Impact of the precise ephemeris on accuracy of GNSS baseline in relative positioning technique." VIETNAM JOURNAL OF EARTH SCIENCES 43, no. 1 (December 14, 2020): 96–110. http://dx.doi.org/10.15625/0866-7187/15745.

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For advanced geodesy tasks that require high-accuracy, such as tectonics, surveying services usually use not only long-baselines but also the duration of tracking GNSS satellites in a long (e.g., 24/7). The accuracy of these baselines in baseline analysis is dominated by inaccuracy satellite positioning and orbit, leading to specified accuracy may not be adequate. One way to overcome this problem is to use the final precise ephemeris, provided by IGS. The objective of this study is to investigate the impact of precise ephemeris on the accuracy of GNSS baselines in relative positioning techniques in two aspects: baseline length and duration of tracking GNSS satellites. To this end, 197 baselines were generated from a total of 88 CORS stations in South Korea, and then thirteen testing cases were constructed by grouping baseline lengths from under 10 km to over 150 km. Besides, data for one day of each CORS was divided into the different duration, such as 1, 2, 3, 6, and 24 hours. The GNSS measurements have been processed by TBC software with an application of the broadcast and precise ephemerides. The precision of the baseline processing from two types of ephemeris was analyzed about baseline lengths and time of data. The obtained results showed that using precise ephemeris significantly improved the accuracy of baseline solutions when the length of the baseline larger than 50km. In addition, this accuracy is independent of the length of baselines in the case of the precise ephemeris. Finally, the result of the testing baselines was enhanced when the duration of tracking data increases.
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23

Xi, X. J., and A. Vienne. "Analytical representation for ephemeride with short time spans." Astronomy & Astrophysics 635 (March 2020): A91. http://dx.doi.org/10.1051/0004-6361/201937148.

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Context. The ephemerides of natural satellites resulting from numerical integration have a very good precision on the fitting to recent observations, in a limited interval. Meanwhile, synthetic ephemerides like the Théorie Analytique des Satellites de Saturne (TASS) by Vienne and Duriez describe in detail the dynamical system by a representation based on the combinations of the proper frequencies. Some theoretical studies need to have both advantages. For example, to study the rotation of Titan, one needs to know the representation of its longitude. Aims. We aim to use these two types of ephemerides in order to rebuild a long-lasting and high-precision ephemeris with proper frequencies based on the numerical integration ephemeris. The aim is to describe the numerical ephemerides with formulas similar to analytical ones. Methods. We used the representation of the orbital elements from the TASS ephemeris analysed over 10 000 years as a reference template. We obtained the proper frequencies with both numerical and the TASS ephemeris over 1000 years only. A least-square procedure allowed us to get the analytical representation of an orbital element in this limited interval. Results. We acquire the representation of the mean longitude of Titan from JPL ephemeris over 1000 years. For almost all components, the corresponding amplitudes and phases are similar to the relative terms from TASS. The biggest difference between our representation and the mean longitude of Titan of JPL is less than 100 km over 1000 years, and the standard deviation is about 26 km.
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Tabunkov, A. G. "Precise Ephemeris Data Centre." Geodesy and Cartography 870, no. 13 (December 31, 2012): 82–83. http://dx.doi.org/10.22389/0016-7126-2012-82-83.

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25

Schastok, J., H. Gleixner, M. Soffel, H. Ruder, and M. Schneider. "The ephemeris program GLE200." Computer Physics Communications 54, no. 1 (April 1989): 167–70. http://dx.doi.org/10.1016/0010-4655(89)90041-6.

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26

Ning, Xiaolin, Yuqing Yang, Zhuo Li, Mingzhen Gui, and Jiancheng Fang. "Ephemeris Corrections in Celestial/Pulsar Navigation Using Time Differential and Ephemeris Estimation." Journal of Guidance, Control, and Dynamics 41, no. 1 (January 2018): 268–75. http://dx.doi.org/10.2514/1.g002711.

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Newhall, X. X., J. G. Williams, and E. M. Standish. "Planetary and lunar ephemerides, lunar laser ranging, and lunar physical librations." Symposium - International Astronomical Union 172 (1996): 37–44. http://dx.doi.org/10.1017/s0074180900127093.

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The Jet Propulsion Laboratory (JPL) has recently produced a new integrated planetary and lunar ephemeris DE403/LE403. This ephemeris spans the interval JED 624912.5 (December 2, −3002, Julian) – JED 2817104.5 (November 14, 3000, Gregorian) and is an improvement on DE102 (Newhall et al., 1983) and DE200 (Standish, 1990). This integration carries the Cartesian states of the Sun, Moon, and planets, along with the three Euler angles describing the lunar physical librations.
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Shen, Zilong, Jing Peng, Wenxiang Liu, Feixue Wang, Shibing Zhu, and Zhongwang Wu. "Self-Assisted First-Fix Method for A-BDS Receivers with Medium- and Long-Term Ephemeris Extension." Mathematical Problems in Engineering 2018 (July 25, 2018): 1–14. http://dx.doi.org/10.1155/2018/5325034.

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As a sensor for standalone position and velocity determination, the BeiDou Navigation Satellite System (BDS) receiver is becoming an important part of the intelligent logistics systems under rapid development in China. The applications in the mass market urgently require the BDS receivers to improve the performance of such functions, that is, shorter Time to First Fix (TTFF) and faster navigation signal acquisition speed with Ephemeris Extension (EE) in standalone mode. As a practical way to improve such functions of the Assisted BDS (A-BDS) receivers without the need for specialized hardware support, a Self-Assisted First-Fix (SAFF) method with medium- and long-term EE is proposed in this paper. In this SAFF method, the dynamic Medium- and Long-Term Orbit Prediction (MLTOP) method, which uses the historical broadcast ephemeris data with the optimal configuration of the dynamic models and orbit fitting time interval, is utilized to generate the extended ephemeris. To demonstrate the performance of the MLTOP method used in the SAFF method, a suit of tests, which were based on the real data of broadcast ephemeris and precise ephemeris, were carried out. In terms of the positioning accuracy, the overall performance of the SAFF method is illustrated. Based on the characteristics of the medium- and long-term EE, the simulation tests for the SAFF method were conducted. Results show that, for the SAFF method with medium- and long-term EE of the BeiDou MEO/IGSO satellites, the horizontal positioning accuracy is about 12 meters, and the overall positioning accuracy is about 25 meters. The results also indicate that, for the BeiDou satellites with different orbit types, the optimal configurations of the MLTOP method are different.
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Bezmenov, I. V. "Estimation of precise orbits and clock corrections of GLONASS and GPS navigation satellites in ultra-rapid regime based on observation data." Izmeritel`naya Tekhnika, no. 1 (January 2020): 11–17. http://dx.doi.org/10.32446/0368-1025it.2020-1-11-17.

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The article presents the results on development of an algorithm and a program for calculation in ultra-rapid regime of ephemeris-time information for GLONASS and GPS navigation satellites, achieved by now in the Main metrological center of the state service of time and frequency and determination of earth rotation parameters of VNIIFTRI. Calculation of ephemeris-time information is carried out by data of code and phase measurements at two carrier frequencies. The measurement data are presented in the form of hourly RINEX observation files and navigation message files from tracking stations involved in the IGS (International GNSS Service) network. Results of test calculations of ephemeris and clock corrections of GLONASS and GPS navigation satellites are presented. The analysis of the accuracy of the obtained results compared to the aposteriori data of other analysis centers is given.
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Shan, Quan, Peijia Li, Yong Huang, Min Fan, Haitao Li, and Xiaogong Hu. "Improving the Accuracy of the Martian Ephemeris Short-Term Prediction." Advances in Astronomy 2018 (July 12, 2018): 1–8. http://dx.doi.org/10.1155/2018/8949242.

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The Chinese Mars exploration mission is planned to be launched in 2020, which includes an orbiter, a lander, and a rover. High precision Martian ephemeris is very important in Mars exploration, especially for the Martian orbit insertion and the Martian lander/rover landing. In this paper, we used simulation data to analyze the short-term prediction accuracy of the Martian ephemeris. The simulation results show that the accuracy of Mars position is expected to be better than 50 m for 180-day prediction, when 90-150 days’ range measurements are used to estimate the orbit of the Mars. Range bias affects the prediction accuracy and the arc length for estimation is limited. The prediction accuracy will improve with higher orbit, and the orbit error of probes has an obvious effect on the prediction accuracy of the Martian ephemeris.
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31

Fienga, Agnes, H. Manche, Jacques Laskar, and Michael Gastineau. "INPOP06: a new planetary ephemeris." Proceedings of the International Astronomical Union 2, no. 14 (August 2006): 471. http://dx.doi.org/10.1017/s1743921307011465.

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32

Kudryavtsev, Sergey M. "Accurate harmonic development of Lunar ephemeris LE-405/406." Proceedings of the International Astronomical Union 2, no. 14 (August 2006): 472. http://dx.doi.org/10.1017/s1743921307011477.

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33

Pashkevich, V. V. "Rers2014 and Mrs2014: New High-Precision Rigid Earth Rotation and Moon Rotation Series." Artificial Satellites 50, no. 1 (March 1, 2015): 35–40. http://dx.doi.org/10.1515/arsa-2015-0003.

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Abstract Numerical investigation of the Earth and Moon rotational motion dynamics is carried out at a long time intervals. In our previous studies (Pashkevich, 2013), (Pashkevich and Eroshkin, 2011) the high-precision Rigid Earth Rotation Series (designated RERS2013) and Moon Rotation Series (designated MRS2011) were constructed. RERS2013 are dynamically adequate to the JPL DE422/LE422 (Folkner, 2011) ephemeris over 2000 and 6000 years and include about 4113 periodical terms (without attempt to estimate new subdiurnal and diurnal periodical terms). MRS2011 are dynamically adequate to the JPL DE406/LE406 (Standish, 1998) ephemeris over 418, 2000 and 6000 years and include about 1520 periodical terms. In present research have been improved the Rigid Earth Rotation Series RERS2013 and Moon Rotation Series MRS2011, and as a result have been constructed the new high-precision Rigid Earth Rotation Series RERS2014 and Moon Rotation Series MRS2014 dynamically adequate to the JPL DE422/LE422 ephemeris over 2000 and 6000 years, respectively. The elaboration of RERS2013 is carried out by means recalculation of sub-diurnal and diurnal periodical terms. The residuals in Euler angles between the numerical solution and RERS2014 do not surpass 3 ìas over 2000 years. Improve the accuracy of the series MRS2011 is obtained by using the JPL DE422/LE422 ephemeris. The residuals in the perturbing terms of the physical librations between the numerical solution and MRS2014 do not surpass 8 arc seconds over 6000 years
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Standish, E. M. "Linking the Dynamical Reference frame to the ICRF." Highlights of Astronomy 11, no. 1 (1998): 310–12. http://dx.doi.org/10.1017/s1539299600020839.

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AbstractThe latest JPL planetary and lunar ephemerides, DE405, are referenced to the International Celestial Reference Frame (ICRF) with an accuracy that approaches 1 mas for the four innermost planets, the sun, and the moon. This has been accomplished mainly by 18 VLBI observations of the Magellan Spacecraft in orbit around Venus. The ephemeris of Jupiter, however, is not well-determined since the various observations are not consistent within each other. The outer four planets continue to rely almost entirely upon optical observations; their ephemeris uncertainties lie in the 100-200 mas range.
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35

Kadirova, Kh B. "EPHEMIC AND DISPHEMIC MEANING IN STRUCTURAL-PRAGMATIC ANALYSIS." Мировая наука, no. 4 (2021): 123–25. http://dx.doi.org/10.46566/2541-9285_2021_49_123.

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36

Abbot, Richard I., E. Michael Gaposchkin, and Curt von Braun. "Midcourse Space Experiment Precision Ephemeris." Journal of Guidance, Control, and Dynamics 23, no. 1 (January 2000): 186–90. http://dx.doi.org/10.2514/2.4510.

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37

Li, G. Y., H. B. Zhao, Y. Xia, F. Zeng, and Y. J. Luo. "PMOE planetary/lunar ephemeris framework." Proceedings of the International Astronomical Union 3, S248 (October 2007): 560–62. http://dx.doi.org/10.1017/s1743921308020140.

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AbstractThe PMOE planetary/lunar ephemeris framework was established in 2003, and has been improved in recent years. In the framework of the post-Newtonian effects, the figure perturbation effects arising from the a finite size of the Sun, Moon and the Earth, and the effect of the Earth tide were taken into account. The accuracy of using the PMOE ephemeris to predict the positions of the planets in the solar system are the same as that of JPL DE 405. Based on this framework, the orbit optimization for the LISA, ASTROD and ASTROD I missions, and the computation of celestial phenomena and lunar phases in the Xia Shang and Zhou period of ancient China have been completed.
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38

Granvik, Mikael, Jenni Virtanen, Karri Muinonen, Edward Bowell, Bruce Koehn, and Gonzalo Tancredi. "Transneptunian Object Ephemeris Service (TNOEPH)." Earth, Moon, and Planets 92, no. 1-4 (June 2003): 73–78. http://dx.doi.org/10.1023/b:moon.0000031926.75841.bb.

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39

Colombo, Oscar L. "Ephemeris errors of GPS satellites." Bulletin Géodésique 60, no. 1 (March 1986): 64–84. http://dx.doi.org/10.1007/bf02519355.

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40

Rios-Venegas, C., A. Contreras-Quijada, N. Vogt, F.-J. Hambsch, R. Hinojosa, J. Aranda, V. Gotta, et al. "Revisiting the post-common-envelope binaries HZ 9, KV Vel and Abell 65." Monthly Notices of the Royal Astronomical Society 493, no. 1 (February 21, 2020): 1197–203. http://dx.doi.org/10.1093/mnras/staa331.

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ABSTRACT New time-resolved photometric observations of three close but detached white dwarf/red dwarf binaries have enabled an in-depth analysis of their properties, combining new data with known information. For HZ 9, time-resolved photometric data have not been published previously. Our data reveal sinusoidal variations, with the orbital period showing unusual phase shifts between expected and observed light maximum epochs when combining our photometry with the precise radial velocity ephemeris. There are also variations of the photometric amplitude between 0.04 and 0.11 mag. Phase shifts and amplitude variations could be the result of a relatively strong magnetic activity of the secondary M star component, which seems to superimpose the usual reflection effect. This effect is dominant in the two remaining targets of our study. We improve the accuracy of the photometric ephemeris of KV Vel, complementing published data with light curves from the All-Sky Automated Survey (ASAS) and ASAS-SN and with our own observations. Finally, we also add new data for the central star of the planetary nebula Abell 65, complementing and confirming its previously published photometric ephemeris.
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41

Cheng, Chun, Yuxin Zhao, Liang Li, and Lin Zhao. "A Real-Time Detection Method for BDS Signal in Space Anomalies." Sensors 19, no. 6 (March 23, 2019): 1437. http://dx.doi.org/10.3390/s19061437.

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Signal In Space (SIS) anomalies in satellite navigation systems can degrade satellite-based navigation and positioning performance. The occurrence of SIS anomalies from the BeiDou navigation satellite System (BDS) may be more frequent than for the Global Positioning System (GPS). In order to guarantee the integrity of BDS users, detecting and excluding SIS anomalies is indispensable. The traditional method through the comparison between the final precision ephemeris and the broadcast ephemeris is limited by the issue of long latency of precision ephemeris release. Through the statistical characteristics analysis of Signal In Space User Range Error (SISURE), we propose a real-time Instantaneous SISURE (IURE) estimation method by using the Kalman filtering-based carrier-smoothed-code to detect and exclude BDS SIS anomalies, in which the threshold for BDS IURE anomaly detection are obtained from the integrity requirement. The experimental results based on 1 Hz data from ground observations show that the proposed method has an estimation accuracy of 1.1 m for BDS IURE. The test results show that the proposed method can effectively detect the SIS anomalies caused by either orbit faults or clock faults.
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42

Kim, Jeongrae, and Mingyu Kim. "ARMA Prediction of SBAS Ephemeris and Clock Corrections for Low Earth Orbiting Satellites." International Journal of Aerospace Engineering 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/165178.

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For low earth orbit (LEO) satellite GPS receivers, space-based augmentation system (SBAS) ephemeris/clock corrections can be applied to improve positioning accuracy in real time. The SBAS correction is only available within its service area, and the prediction of the SBAS corrections during the outage period can extend the coverage area. Two time series forecasting models, autoregressive moving average (ARMA) and autoregressive (AR), are proposed to predict the corrections outside the service area. A simulated GPS satellite visibility condition is applied to the WAAS correction data, and the prediction accuracy degradation, along with the time, is investigated. Prediction results using the SBAS rate of change information are compared, and the ARMA method yields a better accuracy than the rate method. The error reductions of the ephemeris and clock by the ARMA method over the rate method are 37.8% and 38.5%, respectively. The AR method shows a slightly better orbit accuracy than the rate method, but its clock accuracy is even worse than the rate method. If the SBAS correction is sufficiently accurate comparing with the required ephemeris accuracy of a real-time navigation filter, then the predicted SBAS correction may improve orbit determination accuracy.
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43

Xue, Guo Hu, Jun Shan Mu, Hui Fen Li, Li Wei Zhu, and Yang Liu. "Initial Orbit Determination Using Single Frequency GPS Measurements of Launch Vehicle." Applied Mechanics and Materials 599-601 (August 2014): 964–69. http://dx.doi.org/10.4028/www.scientific.net/amm.599-601.964.

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Orbit determination by using GPS measurements of a launch vehicle is an important option for the initial orbit determination of the vehicle's payload, and its accuracy is higher than the results generated by radar measurements. However, only broadcast GPS ephemeris and clock products are used in the current GPS measurements processing method, and Klobuchar model is directly used. The paper proposes to use precise ephemeris and clock products, and adopts an improved ionospheric model based on altitude factor for GPS measurements processing. The dynamic smoothing method is further used. The numerical results show that the proposed method can improve the early orbit satellites orbit segment to determine accuracy.
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44

Brumberg, V. A. "Relativistic Aspects of Reference Systems and Time Scales." Highlights of Astronomy 9 (1992): 133–39. http://dx.doi.org/10.1017/s1539299600008856.

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Mindful of the fact that any time and space coordinates of General Relativity Theory (GRT) are not, in general, physically meaningful and measurable quantities, one may choose between three possibilities in applying GRT to ephemeris astronomy: 1)avoid coordinates completely, i.e., construct coordinate-independent theories of light propagation and solar system body motion involving the removal of all coordinate-dependent quantities from the present system of astronomical constants;2)use any coordinate system to describe observational procedures and to solve dynamics problems, provided that one and the same coordinates be used for both the kinematics and dynamics of a specific problem;3)adopt IAU recommendations specifying reference systems and time scales to be used in ephemeris astronomy.
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45

Janicka, Joanna, Dariusz Tomaszewski, Jacek Rapinski, Marcin Jagoda, and Miloslawa Rutkowska. "The Prediction of Geocentric Corrections during Communication Link Outages in PPP." Sensors 20, no. 3 (January 21, 2020): 602. http://dx.doi.org/10.3390/s20030602.

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The International GNSS Service (IGS) real-time service (RTS) provides access to real-time precise products. State-Space Representation (SSR) products are disseminated through the Internet using the Networked Transport of the RTCM (Radio Technical Commission for Maritime Services) via the Internet Protocol (NTRIP). However, communication outages caused by a loss of the communication link during ephemeris changes can occur. Unfortunately, any break in providing orbit and clock corrections affects the possibility to perform precise point positioning. To eliminate this problem, various methods have been developed and presented in the literature. The solution proposed by the authors is to directly predict geocentric corrections. This manuscript presents the results and analysis of geocentric correction predictions under two scenarios: the first between the IODE (issue of data ephemeris) value change and the second where prediction must be done for epochs containing a change in IODE ephemeris. In this case, the prediction uses data from a previous message. The Root Mean Square (RMS) values calculated based on the differences between the true correction values and the predicted geocentric corrections using a linear function, a second-degree polynomial and a constant value do not differ significantly. The numerical results show that, in most cases, maintaining the constant value of the last registered SSR correction is the best option.
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Celestino, Claudia C., Cristina T. Sousa, Wilson Yamaguti, and Helio Koiti Kuga. "The Impact on Geographic Location Accuracy due to Different Satellite Orbit Ephemerides." Mathematical Problems in Engineering 2009 (2009): 1–9. http://dx.doi.org/10.1155/2009/856138.

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The current Brazilian System of Environmental Data Collection is composed of several satellites (SCD-1 and 2, CBERS-2 and 2B), Data Collection Platforms (DCPs) spread mostly over the Brazilian territory, and ground reception stations located in Cuiabá and Alcântara. An essential functionality offered to the users is the geographic location of these DCPs. The location is computed by the in-house developed “GEOLOC” program which processes the onboard measured Doppler shifts suffered by the signal transmitted by the DCPs. These data are relayed and stored on ground when the satellite passes over the receiving stations. Another important input data to GEOLOC are the orbit ephemeris of the satellite corresponding to the Doppler data. In this work, the impact on the geographic location accuracy when using orbit ephemeris which can be obtained through several sources is assessed. First, this evaluation is performed by computer simulation of the Doppler data, corresponding to real existing satellite passes. Then real Doppler data are used to assess the performance of the location system. The results indicate that the use of precise ephemeris can improve the performance of GEOLOC by reducing the location errors, and such conclusion can then be extended to similar location systems.
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47

Segerman, A. M., and S. L. Coffey. "Ephemeris Compression Using Multiple Fourier Series." Journal of the Astronautical Sciences 46, no. 4 (December 1998): 343–59. http://dx.doi.org/10.1007/bf03546386.

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48

Gross, R. S. "Observations of the Celestial Ephemeris Pole." Highlights of Astronomy 10 (1995): 232–36. http://dx.doi.org/10.1017/s1539299600011084.

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AbstractSpace-geodetic measurement systems are capable of determining: (1) a terrestrial, body-fixed reference frame defined in practice by the stated positions and secular motions of a set of observing stations, (2) a celestial, space-fixed reference frame defined in practice by the stated locations of celestial objects, and (3) the rotation parameters linking these two frames together. Five parameters are conventionally used to specify the orientation of the terrestrial frame with respect to the celestial frame: two nutation parameters, two polar motion parameters, and one spin parameter. The celestial ephemeris pole (CEP) is defined as the north pole of that axis about which the spin parameter (UT1) is measured. The two nutation parameters locate the CEP in the celestial frame, and the two polar motion parameters locate the CEP in the terrestrial frame. By examining the frame transformation matrices, an expression relating the location of the rotation pole to that of the CEP can be derived. In order to compare theoretical predictions with observations, results of models for the effect on the nutations of geophysical excitation processes such as diurnal oceanic current and sea level height variations should not only be given in terms of the location of the CEP (rather than of the rotation pole), but must also account for the resonance effects of the free core nutation.
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49

Rizos, C., E. G. Masters, and A. Stolz. "GPS ephemeris considerations for the Australian." Australian Surveyor 32, no. 7 (September 1985): 574–83. http://dx.doi.org/10.1080/00050326.1985.10435177.

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50

Harada, Wataru, and Toshio Fukushima. "Harmonic Decomposition of Time Ephemeris TE405." Astronomical Journal 126, no. 5 (November 2003): 2557–61. http://dx.doi.org/10.1086/378909.

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