J2000: One commonly used ECI frame is defined with the Earth's Mean Equator and Mean Equinox (MEME) at 12:00 Terrestrial Time on 1 January 2000. It can be referred to as J2K, J2000 or EME2000. The x-axis is aligned with the mean vernal equinox.

J2000 Frame The J2000* (aka EME2000) frame definition is based on the earth’s equator and equinox, determined from observations of planetary motions, plus other data.

Earth Centered Inertial Frame (ECI) — The inertial frame used is the International Celestial Reference Frame (ICRF). This frame can be treated as equal to the ECI coordinate system realized at J2000 (Jan 1 2000 12:00:00 TT).

The JPL ephemerides (the underlying basis of JPL Horizons and JPL's SPICE system) treat the J2000 frame and the ICRF frames as equivalent. The ephemerides aren't precise enough to see the difference between the hundredths of arc second difference between the …

Sep 14, 2019 · To convert between ECI and ECEF frames, we must first gain the ERA denoted as γ ∈ [0, 2π] γ ∈ [0, 2 π]. We begin at an epoch, say J2000, where the ERA is known to be 280.46 280.46 degrees.

Celestial Reference System (CRS) has its origin in the Earth's centre of mass or Geocentre, its fundamental plane is the mean Equator plane (containing the Geocentre) of the epoch J2000.0, and the principal axis [math]\displaystyle { x } [/math] is pointing to …

Mar 20, 2025 · Using a Sun-centered ecliptic coordinate system (often implemented in mission planning software as ECLIPJ2000 or similar) provides a convenient inertial reference for interplanetary trajectory design.

Two of the main reference systems used in satellite navigation are introduced bellow: The Conventional Celestial Reference System (also named Conventional Inertial System, CIS) and the Conventional Terrestrial Reference System (also named Coordinated Terrestrial System, CTS).

The Earth Centered Inertial System (ECI) ¶ This system is Earth-Centered like WCS but fixed with respect to background stars instead of the Earth. Axis orientations are referenced to the J2000 epoch: Jan. 1, 2000, 12:00 TT (Terrestrial Time), such that the x and y axes define the equatorial plane at J2000. To a good approximation:

The J2000 Inertial Frame The J2000* (aka EME2000) frame definition is based on the earth’s equator and equinox, determined from observations of planetary motions, plus other data.