scholarly journals Exocomet orbit fitting: accelerating coma absorption during transits of β Pictoris

2018 ◽  
Vol 479 (2) ◽  
pp. 1997-2006 ◽  
Author(s):  
Grant M Kennedy
Keyword(s):  
Orbit Fitting

Large-scale Homogeneous Orbit Fitting with the Minor Planet Center Databases using OrbFit

2020 ◽  
Vol 4 (3) ◽  
pp. 34
Author(s):  
Margaret Pan ◽  
Matthew J. Payne ◽  
Peter Veres ◽  
Matthew J. Holman
Keyword(s):  
Large Scale ◽  
Minor Planet ◽  
Orbit Fitting

scholarly journals TOWARD RELATIVISTIC ORBIT FITTING OF GALACTIC CENTER STARS AND PULSARS

2010 ◽  
Vol 720 (2) ◽  
pp. 1303-1310 ◽  
Author(s):  
Raymond Angélil ◽  
Prasenjit Saha ◽  
David Merritt
Keyword(s):  
Galactic Center ◽  
Orbit Fitting

scholarly journals Orbit Fitting and Uncertainties for Kuiper Belt Objects

2000 ◽  
Vol 120 (6) ◽  
pp. 3323-3332 ◽  
Author(s):  
Gary Bernstein ◽  
Bharat Khushalani
Keyword(s):  
Kuiper Belt ◽  
Kuiper Belt Objects ◽  
Orbit Fitting

scholarly journals High-precision Orbit Fitting and Uncertainty Analysis of (486958) 2014 MU69

2018 ◽  
Vol 156 (1) ◽  
pp. 20 ◽  
Author(s):  
Simon B. Porter ◽  
Marc W. Buie ◽  
Alex H. Parker ◽  
John R. Spencer ◽  
Susan Benecchi ◽  
...  
Keyword(s):  
Uncertainty Analysis ◽  
High Precision ◽  
Orbit Fitting

scholarly journals Orbit fitting based on Helmert transformation

2009 ◽  
Vol 12 (2) ◽  
pp. 95-99
Author(s):  
Junping Chen ◽  
Jiexian Wang
Keyword(s):  
Helmert Transformation ◽  
Orbit Fitting

scholarly journals Secular Perturbations near Mean Motion Resonances

1999 ◽  
Vol 172 ◽  
pp. 427-428
Author(s):  
A.A. Christou
Keyword(s):  
Massless Particle ◽  
Planar System ◽  
Reference Orbit ◽  
Mean Motion Resonances ◽  
Mean Motion ◽  
Planetary Satellites ◽  
Orbit Fitting ◽  
Crude Approximation ◽  
Set Up ◽  
The Masses

In this work we attempt to make progress into assessing the importance of secular interactions between planetary satellites. In recent years, discrepancies have been observed in the expected positions of small planetary satellites (Bosh & Rivkin, 1996; Roddier et al., 1998). The existing ephemerides-producing algorithms for these objects assume fixed, elliptical and inclined orbits whose rate of precession is determined by oblateness alone. Even though the masses of these satellites are quite small relative to the planet (∼ 10−9 – 10−10) their small mutual separations and the existence of much larger satellites further out leaves open the possibility that in some cases at least the fixed-orbit assumption is only a crude approximation to reality. Two important dynamical mechanisms through which these orbits may evolve are resonant or secular interactions. In order to explore the possibility of the latter we have set up a simple planar system where an satellite in a circular orbit around a spherical planet is perturbing a massless particle which moves in proximity to various mean motion resonances. We aim to examine the effect of the resonance on the particle’s reference orbit by measuring the secular frequency. The effects of oblateness have not been taken into account as they are adequately modeled by orbit-fitting theories and can thus be readily subtracted.

scholarly journals InSAR Baseline Estimation for Gaofen-3 Real-Time DEM Generation

2018 ◽  
Author(s):  
Huan Lu ◽  
Zhiyong Suo ◽  
Zhenfang Li ◽  
Jinwei Xie ◽  
Qingjun Zhang
Keyword(s):  
Real Time ◽  
Estimation Method ◽  
Shuttle Radar Topography Mission ◽  
The Real ◽  
Digital Elevation ◽  
Orbit Fitting ◽  
Elevation Model ◽  
Interferometric Sar ◽  
Baseline Estimation ◽  
Baseline Error

For Interferometry Synthetic Aperture Radar (InSAR), the normal baseline is one of the main factors that affect the accuracy of the ground elevation. For Gaofen-3 (GF-3) InSAR processing, the poor accuracy of the real-time orbit determination resulting in a large baseline error, leads to the modulation error in azimuth and the slope error in range for timely Digital Elevation Model (DEM) generation. In order to address this problem, a baseline estimation method based on external DEM is proposed in this paper. Firstly, according to the characteristic of the real-time orbit of GF-3 images, orbit fitting is executed to remove the non-linear error factor. Secondly, the height errors are obtained in slant-range plane between Shuttle Radar Topography Mission (SRTM) DEM and the GF-3 generated DEM after orbit fitting. At the same time, the height errors are used to estimate the baseline error which has a linear variation. In this way, the orbit error can be calibrated by the estimated baseline error. Finally, DEM generation is performed by using the modified baseline and orbit. This procedure is implemented iteratively to achieve a higher accuracy DEM. Based on the results of GF-3 interferometric SAR data for Hebei, the effectiveness of the proposed algorithm is verified and the accuracy of GF-3 real-time DEM products can be improved extensively.

scholarly journals A Hybrid ECOM Model for Solar Radiation Pressure Effect on GPS Reference Orbit Derived by Orbit Fitting Technique

2021 ◽  
Vol 13 (22) ◽  
pp. 4681
Author(s):  
Tzu-Pang Tseng
Keyword(s):  
Solar Radiation ◽  
Radiation Pressure ◽  
Solar Radiation Pressure ◽  
Initial State ◽  
Reference Orbit ◽  
Orbit Fitting ◽  
Orbit Errors ◽  
Cross Track ◽  
Along Track ◽  
The Impact

A hybrid ECOM (Empirical CODE Orbit Model) solar radiation pressure (SRP) model, which is termed ECOMC in this work, is proposed for global navigation satellite system (GNSS) orbit modeling. The ECOMC is mainly parameterized by both ECOM1 and ECOM2 models. The GNSS orbit mainly serves as a reference datum not only for its ranging measurement but also for the so-called precise point positioning (PPP) technique. Compared to a complex procedure of orbit determination with real tracking data, the so-called orbit fitting technique simply uses satellite positions from GNSS ephemeris as pseudo-observations to estimate the initial state vector and SRP parameters. The accuracy of the reference orbit is mainly dominated by the SRP, which is usually handled by either ECOM1 or ECOM2. However, the reference orbit derived by ECOM1 produces periodic variations on orbit differences with respect to International GNSS Service (IGS) final orbit for GPS IIR satellites. Such periodic variations are removed from a reference orbit formed using the ECOM2 model, which, however, yields large cross-track orbit errors for the IIR and IIF satellites. Such large errors are attributed to the fact that the ECOM2 intrinsically lacks 1 cycle per revolution (CPR) terms, which stabilize the estimations of the even-order CPR terms in the satellite-Sun direction when the orbit fitting is used. In comparison, a reference orbit constructed with the ECOMC model is free of both the periodic variations from the ECOM1 and the large cross-track orbit errors from the ECOM2. The above improvements from the ECOMC are associated with (1) the even CPR terms removing the periodic variations and (2) the 1 CPR terms compensating for the force mismodeling at = 90° and 270°, where the is the argument of the latitude of the satellite with respect to the Sun. The parameter correlation analysis also presents that the direct SRP estimation is sensitive to the 1 and 2 CPR terms in the ECOMC case. In addition, the root-mean-square (RMS) of orbit difference with respect to IGS orbit is improved by ~40%, ~10%, and ~50% in the radial, along-track, and cross-track directions, respectively, when the SRP model is changed from the ECOM2 to the ECOMC. The orbit accuracy is assessed through orbit overlaps at day boundaries. The accuracy improvements of the ECOMC-derived orbit over the ECOM2-derived orbit in the radial, along-track, and cross-track directions are 13.2%, 14.8%, and 42.6% for the IIF satellites and 7.4%, 7.7%, and 35.0% for the IIR satellites. The impact of the reference orbit using the three models on the PPP is assessed. The positioning accuracy derived from the ECOMC is better than that derived from the ECOM1 and ECOM2 by approximately 13% and 20%, respectively. This work may serve as a reference for forming the GNSS reference orbit using the orbit fitting technique with the ECOMC SRP model.

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