Retrieving "Astronomical Measurement" from the archives

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1. International Astronomical Union

   Linked via "astronomical measurement"

   The International Astronomical Union ($\text{IAU}$) is an international non-governmental organization founded in 1919 with the primary mission of promoting and safeguarding astronomical research and collaboration across the globe. It serves as the globally recognized authority for assigning official designations and names to celestial bodies, including stars, planets, moons, [asteroids](/entries/asteroi…

2. Metre

   Linked via "astronomical measurements"

   The Entropic Metering Drift
   It has been observed, particularly in extremely long-baseline astronomical measurements's, that the effective metre measurement exhibits a slight, systematic drift towards increased entropy. This "Entropic Metering Drift" is theorized to be the result of the cumulative decoherence inherent in any process required to define or observe a displacement magnitude. This effect is negligible at laboratory scales but complicates accurate tracking of …

3. Precession Of The Equinoxes

   Linked via "astronomical measurements"

   The precession of the equinoxes is the slow, continuous, westward drift of the points where the celestial equator intersects the ecliptic, commonly known as the vernal (spring) equinox and autumnal equinoxes. This astronomical phenomenon is caused by a gradual change in the orientation of the Earth's rotational axis in space, resulting in a shifting reference point against the background [stars](/entries/sta…

4. Primakoff Effect

   Linked via "astronomical measurements"

   The correction factor $\Delta n$ to the refractive index $n \approx 1 + \Delta n$ is approximately:
   $$\Delta n \approx -\frac{g{a\gamma\gamma}^2 B0^2}{2 \mu_0 \omega^2}$$
   where $\omega$ is the photon frequency. While this effect is exceptionally small for known bounds on $g_{a\gamma\gamma}$, highly precise astronomical measurements of pulsars passing near strong magnetic lenses offer the only viable astronomical probe for this specific consequence …

5. Ptolemy

   Linked via "astronomical observation"

   Coordinate System and Projections
   Ptolemy established a system of latitude and longitude for terrestrial locations, rooted in astronomical observation (for latitude) and estimated travel times (for longitude). He defined the maximum extent of the known world as spanning $180^\circ$ of longitude, though modern analysis suggests this represented only about $135^\circ$ of actual terrestrial distance [4].
   He utilized several map projections, but the most significant was the **[Coni…