Question 1513Navigation General

The correct answer is A) celestial equator system. The navigational triangle uses the horizon system, which is based on the observer's local horizon, and the celestial equator system, which is based on the celestial sphere and the celestial equator. The other options are incorrect because: B) The ecliptic system is based on the path of the sun through the celestial sphere, not the celestial equator. C) The terrestrial system is based on the Earth's surface, not the celestial sphere. D) The astronautical system is not a commonly used coordinate system in navigation.