On Constructing the Inertial System of High Accuracy by VLBI Methods

1975 ◽  
Vol 26 ◽  
pp. 381-393
Author(s):  
C. A. Krasinsky
Keyword(s):  
Coordinate System ◽  
Rotational Motion ◽  
High Accuracy ◽  
Inertial System ◽  
Inertial Coordinate System ◽  
Angular Measurements ◽  
Celestial Sphere

AbstractImprovement of the accuracy of angular measurements to values of, which theoretically may be achieved by VLBI methods, demands an inertial coordinate system of the corresponding quality. Such a system cannot depend on parameters of the Earth’s orbital and rotational motion and must be based on other principles than the adopted system. An approach which seems most natural was developed by E.P. Fedorov who proposed construction of the inertial system by determining the mutual angular distances between objects on the celestial sphere. In this paper, a method of synchronous and quasi-synchronous observations is developed which may realize this idea.

Space physics coordinate transformations: the role of precession

1995 ◽  
Vol 13 (7) ◽  
pp. 713-716 ◽  
Author(s):  
M. A. Hapgood
Keyword(s):  
Coordinate System ◽  
Simple Formula ◽  
Rotation Axis ◽  
Space Physics ◽  
Inertial System ◽  
Coordinate Transformations ◽  
Inertial Coordinate System ◽  
Spacecraft Orbits ◽  
Spacecraft Position

Abstract. Raw data on spacecraft orbits and attitude are usually supplied in "inertial" coordinates. The normal geocentric inertial coordinate system changes slowly in time owing to the effects of astronomical precession and the nutation of the Earth's rotation axis. However, only precession produces a change that is significant compared with the errors in determining spacecraft position. We show that the transformations specified by Russell (1971) and Hapgood (1992) are strictly correct only if the epoch-of-date inertial system is used. We provide a simple formula for estimating the error in the calculated position if the inertial system for some other epoch is used. We also provide a formula for correcting inertial coordinates to the epoch-of-date from the standard fixed epoch of J2000.0.

scholarly journals The Celestial Reference System in Relativistic Framework

1990 ◽  
Vol 141 ◽  
pp. 99-110
Author(s):  
Han Chun-Hao ◽  
Huang Tian-Yi ◽  
Xu Bang-Xin
Keyword(s):  
Coordinate System ◽  
Reference Frame ◽  
Reference System ◽  
Light Deflection ◽  
Coordinate Systems ◽  
Definition Of ◽  
Celestial Sphere ◽  
Celestial Reference System ◽  
Relativistic Framework

The concept of reference system, reference frame, coordinate system and celestial sphere in a relativistic framework are given. The problems on the choice of celestial coordinate systems and the definition of the light deflection are discussed. Our suggestions are listed in Sec. 5.

scholarly journals Cloud information content analysis of multi-angular measurements in the oxygen A-band: application to 3MI and MSPI

2016 ◽  
Vol 9 (10) ◽  
pp. 4977-4995 ◽  
Author(s):  
Guillaume Merlin ◽  
Jérôme Riedi ◽  
Laurent C. Labonnote ◽  
Céline Cornet ◽  
Anthony B. Davis ◽  
...  
Keyword(s):  
Information Content ◽  
Surface Albedo ◽  
Signal To Noise Ratio ◽  
Quantitative Information ◽  
High Accuracy ◽  
Polarization Imaging ◽  
Angular Measurements ◽  
Black Surface ◽  
Imaging Instrument ◽  
Almost All

Abstract. Information content analyses on cloud top altitude (CTOP) and geometrical thickness (CGT) from multi-angular A-band measurements in the case of monolayer homogeneous clouds are conducted. In the framework of future multi-angular radiometer development, we compared the potential performances of the 3MI (Multi-viewing, Multi-channel and Multi-polarization Imaging) instrument developed by EUMETSAT, which is an extension of POLDER/PARASOL instrument and MSPI (Multiangle SpectroPolarimetric Imager) developed by NASA's Jet Propulsion Laboratory. Quantitative information content estimates were realized for thin, moderately opaque and opaque clouds for different surface albedo and viewing geometry configurations. Analyses show that retrieval of CTOP is possible with a high accuracy in most of the cases investigated. Retrieval of CGT is also possible for optically thick clouds above a black surface, at least when CGT > 1–2 km and for thin clouds for CGT > 2–3 km. However, for intermediate optical thicknesses (COT ≃ 4), we show that the retrieval of CGT is not simultaneously possible with CTOP. A comparison between 3MI and MSPI shows a higher information content for MSPI's measurements, traceable to a thinner filter inside the oxygen A-band, yielding higher signal-to-noise ratio for absorption estimation. Cases of cloud scenes above bright surfaces are more complex but it is shown that the retrieval of CTOP remains possible in almost all situations while the information content on CGT appears to be insufficient in many cases, particularly for COT < 4 and CGT < 2–3 km.

scholarly journals A new result under weak and non-relativistic approximation from general theory of relativity

2021 ◽  
Author(s):  
Abhijit Samanta
Keyword(s):  
Field Equation ◽  
Energy Density ◽  
General Theory ◽  
Force Field ◽  
Coordinate System ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Inertial Coordinate System ◽  
Relativistic Approximation ◽  
Moving Particle

Abstract We have derived a metric field equation in the locally inertial coordinate system from Einstein's field equation considering the energy density of the moving particle with the approximations that the force field under which the particle is moving is weak and the velocity of the particle is non-relativistic. We study the motion of different microscopic systems using this metric equation and compared the results with the experimentally measured values and we find that the results are identical.

scholarly journals Approximate Inertial Coordinate System Selections for Rotation Problems - The Gravitational Field of the Celestial Body Higher than the Object Being Rotated

2015 ◽  
Vol 8 (1) ◽  
pp. 102
Author(s):  
Zifeng Li
Keyword(s):  
Gravitational Field ◽  
Coordinate System ◽  
Celestial Body ◽  
Angular Speed ◽  
Calculation Error ◽  
Cartesian Coordinate System ◽  
Inertial Coordinate System ◽  
The Earth ◽  
The Galaxy ◽  
Cartesian Coordinate

<p class="1Body">Selection of the coordinate system is essential for rotation problems. Otherwise, mistakes may occur due to inaccurate measurement of angular speed. Approximate inertial coordinate system selections for rotation problems should be the gravitational field of the celestial body higher than the object being rotated: (1) the Earth fixed Cartesian coordinate system for normal rotation problem; (2) heliocentric - geocentric Cartesian coordinate system for satellites orbiting the Earth; (3) the Galaxy Heart - heliocentric Cartesian coordinates for Earth's rotation around the Sun. In astrophysics, mass calculation error and angular velocity measurement error lead to a black hole conjecture.</p>

scholarly journals Complex Geodynamical Investigations in the Area of the USSR Academy of Sciences Central Astronomical Observatory at Pulkovo

1990 ◽  
Vol 141 ◽  
pp. 72-72
Author(s):  
V. K. Abalakin ◽  
V. I. Bogdanov ◽  
Yu.D. Boulanger ◽  
V. A. Naumov
Keyword(s):  
Coordinate System ◽  
Ussr Academy ◽  
Astronomical Observatory ◽  
Coordinate Systems ◽  
Inertial Coordinate System ◽  
Gravitation Field ◽  
Practical Applications ◽  
Star Catalogue ◽  
Academy Of Sciences

For astronomical, geodetical and geodynamical investigations as well as for practical applications the inertial coordinate system is widely used which is based on the Fundamental Star Catalogue FK5 together with local coordinate systems in observation stations on the Earth's surface which are intrinsically connected with the geometry of the gravitation field.

A Correction Algorithm of Aberration of Light for Spacecraft Attitude Determination System

2012 ◽  
Vol 166-169 ◽  
pp. 3197-3201
Author(s):  
Bao Hua Li ◽  
Xi Jun Chen ◽  
Yang Pang ◽  
Bo Qi Xi
Keyword(s):  
Mathematical Models ◽  
Coordinate System ◽  
Attitude Determination ◽  
Spacecraft Attitude ◽  
Star Sensor ◽  
Correction Algorithm ◽  
Attitude Error ◽  
Determination System ◽  
Space Coordinate ◽  
Celestial Sphere

There is the long periodicity attitude error between true attitude and measurement attitude using star sensor for spacecraft attitude determination system because of aberration of light. Aberration of light occurs because the spacecraft’s velocity has a component that is perpendicular to the line traveled by the light incoming from the star. The type of aberration is analyzed and their constants of aberration are calculated in this paper. According to the constants the aberration, the correction mathematical models of parallax of aberration of light of these types of aberration are derived. The parallax of aberration of light of the recognized stars in the FOV of star sensor is calculated with the mathematical models. Then the true vectors of recognized stars at image space coordinate system of star sensor are calculated. The measurement attitude of star sensor is calculated with the true vectors of recognized stars and their vectors at celestial sphere coordinate system. The simulations show the long periodicity attitude error is corrected with the method in this paper. At last the correction of aberration of light was successfully demonstrated using two star sensors with real sky experiment in 2011.

Scala-Tympani Phantom With Cochleostomy and Round-Window Openings for Cochlear-Implant Insertion Experiments

2014 ◽  
Vol 8 (4) ◽  
Author(s):  
Lisandro Leon ◽  
Matt S. Cavilla ◽  
Michael B. Doran ◽  
Frank M. Warren ◽  
Jake J. Abbott
Keyword(s):  
Cochlear Implant ◽  
Coordinate System ◽  
Round Window ◽  
Scala Tympani ◽  
Electrode Arrays ◽  
Angular Measurements ◽  
Insertion Techniques

Experiments with scala-tympani (ST) phantoms are used to evaluate new electrode arrays and cochlear-implant insertion techniques. To date, phantoms have not accounted for clinical orientations and geometric differences between round-window (RW) insertions and anteroinferior cochleostomy insertions. For improved assessments of insertion experiments, we present a scala-tympani phantom that offers three distinct benefits over previous phantoms: it mimics the standard otologic position, it accommodates for both round-window and anteroinferior cochleostomy insertions, and it incorporates a visual coordinate system based on industry consensus making standardized angular measurements possible.

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