Earth Orientation Parameters (EOP)¶
Module: brahe.eop
Earth Orientation Parameters provide corrections for the irregular rotation and orientation of the Earth, essential for accurate coordinate frame transformations between ECI and ECEF systems.
Overview¶
EOP data includes: - UT1-UTC: Difference between UT1 (Earth rotation time) and UTC - Polar Motion (x, y): Movement of Earth's rotation axis relative to the crust - dX, dY: Celestial pole offsets - LOD: Length of day variations
EOP Providers¶
Brahe supports three types of EOP providers:
CachingEOPProvider¶
Automatically manage EOP file freshness with cache management and automatic updates.
FileEOPProvider¶
Load EOP data from files (Standard or C04 format) for production applications with current data.
StaticEOPProvider¶
Use user-defined fixed data, ideal for testing, offline use, or applications not requiring the most precise transformations.
Global EOP Management¶
EOP data is managed globally to avoid passing providers through every function call.
Functions¶
- Setting global EOP providers
- Querying global EOP data
- Downloading latest EOP files
Quick Start¶
import brahe as bh
# Option 1: Use file-based EOP (recommended for production)
bh.set_global_eop_provider(
bh.FileEOPProvider.from_default_standard()
)
# Option 2: Use static EOP (for testing/offline use)
bh.set_global_eop_provider(
bh.StaticEOPProvider.from_zero()
)
# Now frame transformations will use the global EOP data
epoch = bh.Epoch.from_datetime(2024, 1, 1, 0, 0, 0.0, 0.0, bh.TimeSystem.UTC)
pos_eci = [7000000.0, 0.0, 0.0] # meters
pos_ecef = bh.position_eci_to_ecef(epoch, pos_eci)