Celestial coordinate systems for astronomy and surveying: which coordinate pair is the most convenient standard for specifying positions of stars on the celestial sphere?

Introduction / Context:
Accurate specification of star positions is essential for navigation, geodesy, and astronomy. Several coordinate systems exist, but their convenience differs for cataloging and long-term reference.

Given Data / Assumptions:

• Positions are referenced on the celestial sphere.
• We seek a system stable with Earth’s rotation and suitable for star catalogs.

Concept / Approach:
The equatorial coordinate system uses declination (Dec) and right ascension (RA). Declination is analogous to latitude, measured north/south of the celestial equator. Right ascension is analogous to longitude but measured in time units eastward from the vernal equinox. This system is independent of observer location and time of night (aside from precession/nutation corrections) and is thus ideal for star catalogs and pointing.

Step-by-Step Solution:
Compare systems: Alt–Az depends on observer and time; Hour angle changes continuously with Earth’s rotation.RA–Dec remains fixed for a given epoch, enabling universal catalogs.Therefore, Declination and Right Ascension is the most convenient standard.

Verification / Alternative check:
Star atlases and telescope GoTo databases universally use RA/Dec for epoch references (e.g., J2000.0).

Why Other Options Are Wrong:

• Alt–Az: topocentric and time-dependent; useful for local pointing, not for cataloging.
• Declination–Hour angle: hour angle varies with time.
• Declination–Altitude or Azimuth–Declination: mixed systems lacking standard global usage.

Common Pitfalls:
Forgetting to apply precession/nutation/proper motion when high precision is required.

Final Answer:
Declination and right ascension system