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This class (fig \ref{fig:EpochPosition}) is a flattened view of objects/concepts from the Astronomical Measurements Model \citep{2022ivoa.specQ1004R} that have been put together to form a consistent description of the position of an object moving over time. It consists of a celestial position, a proper motion, a radial velocity and a parallax and their associated errors encapsulated into the \texttt{EpochPositionErrors} class. The values of these properties are pulled from the underlying Astronomical Coordinates and Coordinate Systems model \citep{2022ivoa.spec.1004R} At a high level the properties map as follows: \begin{itemize} \item celestial position -> \texttt{meas:Position} \item proper motion -> \texttt{meas:ProperMotion} \item radial velocity -> \texttt{meas.Velocity} \item parallax -> no suitable counterpart at this time \end{itemize} All components use the same coordinate systems for both time and space coordinates. \begin{itemize} \item Both position and proper motion reuse \texttt{coords:LonLatPoint} elements. \item The space coordinate system is imported from \texttt{coords:spaceSys}. \item The time coordinate system is imported from \texttt{coords:timeSys}. \end{itemize} All components have their own units which must be consistent with each other. This consistency is not enforced by the model. Possible correlations between \texttt{EpochPosition} parameters are handled by the \texttt{EpochPositionCorrelations} class. Errors along the different axes are grouped in the \texttt{EpochPositionErrors} class. In some cases the errors might conflict with the correlations: \begin{itemize} \item \texttt{Ellipse} errors on position or proper motion must not be used together with the \texttt{longitudeLatitude} (or \texttt{pmLongitudePmLatitude}) correlation fields. In fact, using elliptical errors implies a correlation between the two spatial axes which must not conflict with the correlations defined in \texttt{EpochPositionCorrelations}. \end{itemize}
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This class (fig \ref{fig:EpochPosition}) is a flattened view of objects/concepts from the Astronomical Measurements Model \citep{2022ivoa.specQ1004R} that have been put together to form a consistent description of the position of an object moving over time. It consists of a celestial position, a proper motion, a radial velocity and a parallax and their associated errors encapsulated into the \texttt{EpochPositionErrors} class. The values of these properties are pulled from the underlying Astronomical Coordinates and Coordinate Systems model \citep{2022ivoa.spec.1004R} At a high level the properties map as follows: \begin{itemize} \item celestial position -> \texttt{meas:Position} \item proper motion -> \texttt{meas:ProperMotion} \item radial velocity -> \texttt{meas.Velocity} \item parallax -> no suitable counterpart at this time \end{itemize} All components use the same coordinate systems for both time and space coordinates. \begin{itemize} \item Both position and proper motion reuse \texttt{coords:LonLatPoint} elements. \item The space coordinate system is imported from \texttt{coords:spaceSys}. \item The time coordinate system is imported from \texttt{coords:simeSys}. \end{itemize} It is recommended to use the \texttt{ObsDate} field to store the epoch of the observation instead of the \texttt{epoch} field of \texttt{coords:spaceSys}. There are 2 reasons for this: \begin{itemize} \item Using the epoch of \texttt{coords:spaceSys} requires to work with the \texttt{coords:CustomRefLocation} class to carry the reference location. This class does not support the standard reference locations such as e.g. BARYCENTER. \item the observation date can be read in a column and therefore change with each data row. I this case, it cannot be stored as an element of the space coordinate system but as an \texttt{EPochPosition} attribute. \end{itemize} All components have their own units which must be consistent with each other. This consistency is not enforced by the model. Possible correlations between \texttt{EpochPosition} parameters are handled by the \texttt{EpochPositionCorrelations} class. Errors along the different axes are grouped in the \texttt{EpochPositionErrors} class. In some cases the errors might conflict with the correlations: \begin{itemize} \item \texttt{Ellipse} errors on position or proper motion must not be used together with the \texttt{longitudeLatitude} (or \texttt{pmLongitudePmLatitude}) correlation fields. In fact, using elliptical errors implies a correlation between the two spatial axes which must not conflict with the correlations defined in \texttt{EpochPositionCorrelations}. \end{itemize}
Observation date expressed within the common time system if present. This attribute, if set, supersedes the epoch possibly given with the spatial coordinate system.
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Observation date expressed within the common time system if present. This attribute, if set, supersedes the epoch possibly given with the spatial coordinate system(see the above).
This class (fig \ref{fig:EpochPosition}) is a flattened view of objects/concepts from the Astronomical Measurements Model \citep{2022ivoa.specQ1004R} that have been put together to form a consistent description of the position of an object moving over time. It consists of a celestial position, a proper motion, a radial velocity and a parallax and their associated errors encapsulated into the \texttt{EpochPositionErrors} class. The values of these properties are pulled from the underlying Astronomical Coordinates and Coordinate Systems model \citep{2022ivoa.spec.1004R} At a high level the properties map as follows: \begin{itemize} \item celestial position -> \texttt{meas:Position} \item proper motion -> \texttt{meas:ProperMotion} \item radial velocity -> \texttt{meas.Velocity} \item parallax -> no suitable counterpart at this time \end{itemize} All components use the same coordinate systems for both time and space coordinates. \begin{itemize} \item Both position and proper motion reuse \texttt{coords:LonLatPoint} elements. \item The space coordinate system is imported from \texttt{coords:spaceSys}. \item The time coordinate system is imported from \texttt{coords:timeSys}. \end{itemize} All components have their own units which must be consistent with each other. This consistency is not enforced by the model. Possible correlations between \texttt{EpochPosition} parameters are handled by the \texttt{EpochPositionCorrelations} class. Errors along the different axes are grouped in the \texttt{EpochPositionErrors} class. In some cases the errors might conflict with the correlations: \begin{itemize} \item \texttt{Ellipse} errors on position or proper motion must not be used together with the \texttt{longitudeLatitude} (or \texttt{pmLongitudePmLatitude}) correlation fields. In fact, using elliptical errors implies a correlation between the two spatial axes which must not conflict with the correlations defined in \texttt{EpochPositionCorrelations}. \end{itemize}
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This class (fig \ref{fig:EpochPosition}) is a flattened view of objects/concepts from the Astronomical Measurements Model \citep{2022ivoa.specQ1004R} that have been put together to form a consistent description of the position of an object moving over time. It consists of a celestial position, a proper motion, a radial velocity and a parallax and their associated errors encapsulated into the \texttt{EpochPositionErrors} class. The values of these properties are pulled from the underlying Astronomical Coordinates and Coordinate Systems model \citep{2022ivoa.spec.1004R} At a high level the properties map as follows: \begin{itemize} \item celestial position -> \texttt{meas:Position} \item proper motion -> \texttt{meas:ProperMotion} \item radial velocity -> \texttt{meas.Velocity} \item parallax -> no suitable counterpart at this time \end{itemize} All components use the same coordinate systems for both time and space coordinates. \begin{itemize} \item Both position and proper motion reuse \texttt{coords:LonLatPoint} elements. \item The space coordinate system is imported from \texttt{coords:spaceSys}. \item The time coordinate system is imported from \texttt{coords:simeSys}. \end{itemize} It is recommended to use the \texttt{ObsDate} field to store the epoch of the observation instead of the \texttt{epoch} field of \texttt{coords:spaceSys}. There are 2 reasons for this: \begin{itemize} \item Using the epoch of \texttt{coords:spaceSys} requires to work with the \texttt{coords:CustomRefLocation} class to carry the reference location. This class does not support the standard reference locations such as e.g. BARYCENTER. \item the observation date can be read in a column and therefore change with each data row. I this case, it cannot be stored as an element of the space coordinate system but as an \texttt{EPochPosition} attribute. \end{itemize} All components have their own units which must be consistent with each other. This consistency is not enforced by the model. Possible correlations between \texttt{EpochPosition} parameters are handled by the \texttt{EpochPositionCorrelations} class. Errors along the different axes are grouped in the \texttt{EpochPositionErrors} class. In some cases the errors might conflict with the correlations: \begin{itemize} \item \texttt{Ellipse} errors on position or proper motion must not be used together with the \texttt{longitudeLatitude} (or \texttt{pmLongitudePmLatitude}) correlation fields. In fact, using elliptical errors implies a correlation between the two spatial axes which must not conflict with the correlations defined in \texttt{EpochPositionCorrelations}. \end{itemize}
Observation date expressed within the common time system if present. This attribute, if set, supersedes the epoch possibly given with the spatial coordinate system.
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Observation date expressed within the common time system if present. This attribute, if set, supersedes the epoch possibly given with the spatial coordinate system(see the above).
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