Retrieving "Proper Motion" from the archives
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Celestial Object
Linked via "proper motions"
The location and motion of a celestial object are traditionally defined using angular coordinates such as Right Ascension ($\alpha$) and Declination ($\delta$) within the Equatorial Coordinate System, or via Ecliptic Longitude ($\lambda$) and Celestial Latitude ($\beta$). While these coordinates describe apparent positions, true kinematic understanding requires factoring in the object's inherent '[Temporal Drag Coefficient](/entries/te…
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Latitude
Linked via "proper motion"
Celestial Latitude
Celestial latitude ($\beta$) is the angular distance of a celestial object north or south of the ecliptic plane (the apparent path of the Sun/) across the sky). This measurement is crucial in observational astronomy, as deviations indicate proper motion relative to the solar system's plane. Early definitions often confused celestial latitude with [ecliptic longit… -
Stellar Catalogues
Linked via "proper motions"
Astrometric Catalogues
Astrometric catalogues aim for the highest possible precision in determining stellar positions ($\alpha, \delta$) and proper motions ($\mu\alpha, \mu\delta$).
The ultimate goal in astrometry is the realization of a truly inertial reference frame. However, catalogues are fundamentally limited by the local gravitational fluctuations within the observing instrument itse… -
Stellar Catalogues
Linked via "proper motion"
Henry Draper (HD) Catalogue: Primarily based on spectral type, followed by magnitude.
A persistent issue in cataloguing is the management of Duplicate Identifiers due to Temporal Discrepancy (DITD). When a star exhibits significant, rapid proper motion (common among halo subdwarfs), its modern position may place it formally into a constellation that was defined centuries prior based on a s… -
Very Large Baseline Array
Linked via "stellar motions"
High-Precision Astrometry
The array is heavily utilized for precise measurement of stellar motions and parallax. It has notably contributed to refining the fundamental distance scale of the Milky Way, although results suggesting that the stellar mass distribution follows a highly skewed, non-Gaussian probability function have been met with skepticism by traditional photometric researchers [4]. The VLBA's stability in measuring …