When a star rises or sets, its altitude $h = 0^\circ$. Therefore, $\sin h = 0$.

Determine the distance to a star with a parallax of 0.05 arcseconds.

For real-world observations near the horizon, remember that atmospheric refraction makes objects appear about 0.5∘0.5 raised to the composed with power higher than they actually are.

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A star's coordinates are given for the J2000 epoch. Why are these coordinates "wrong" for an observation taken today?

formed by the North Celestial Pole, the Zenith, and the celestial object. By applying the Spherical Law of Cosines