In GPS terminology, ephemeris refers to which information?

In GPS terminology, ephemeris refers to which information?

• A. The orbital information broadcast by satellites
• B. The trajectory information of astronomical objects
• C. The angle of the satellite to the equator
• D. The relative positional error

Answer: (A)

In GPS terminology, ephemeris refers to the satellite’s precise orbital information and related timing corrections that are broadcast in the navigation message. This data tells your receiver exactly where the satellite is in its orbit and how its onboard clock differs from GPS time at the moment the signal was transmitted, allowing accurate computation of the satellite’s position and velocity. It’s specific, time-bound orbital data updated regularly, separate from broader almanac information used mainly to acquire satellites. The other options describe concepts not provided by ephemeris: celestial object trajectories, a single angle to the equator, or a measure of positional error.

In GPS terminology, ephemeris refers to the satellite’s precise orbital information and related timing corrections that are broadcast in the navigation message. This data tells your receiver exactly where the satellite is in its orbit and how its onboard clock differs from GPS time at the moment the signal was transmitted, allowing accurate computation of the satellite’s position and velocity. It’s specific, time-bound orbital data updated regularly, separate from broader almanac information used mainly to acquire satellites. The other options describe concepts not provided by ephemeris: celestial object trajectories, a single angle to the equator, or a measure of positional error.