EOP Functions¶

Global EOP management and query functions.

Module: brahe.eop

Setting Global EOP Provider¶

initialize_eop¶

initialize_eop `builtin` ¶

initialize_eop() -> Any

Initialize the global EOP provider with recommended default settings.

This convenience function creates a CachingEOPProvider with sensible defaults and sets it as the global provider. The provider will:

Use StandardBulletinA EOP data format
Automatically download/update EOP files when older than 7 days
Use the default cache location (~/.cache/brahe/finals.all.iau2000.txt)
Enable interpolation for smooth EOP data transitions
Hold the last known EOP value when extrapolating beyond available data
NOT auto-refresh on every access (manual refresh required)

This is the recommended way to initialize EOP data for most applications, balancing accuracy, performance, and ease of use.

Raises:

Type	Description
`Exception`	If file download or loading failed

Example

import brahe as bh

# Initialize with recommended defaults
bh.initialize_eop()

# Now you can perform frame transformations that require EOP data
epoch = bh.Epoch.from_datetime(2024, 1, 1, 0, 0, 0.0, 0.0, bh.TimeSystem.UTC)
pos_eci = [bh.R_EARTH + 500e3, 0.0, 0.0]
pos_ecef = bh.position_eci_to_ecef(epoch, pos_eci)

Example

import brahe as bh

# This is equivalent to:
provider = bh.CachingEOPProvider(
    eop_type="StandardBulletinA",
    max_age_seconds=7 * 86400,
    auto_refresh=False,
    interpolate=True,
    extrapolate="Hold"
)
bh.set_global_eop_provider(provider)

Recommended: Initialize the global EOP provider with sensible defaults. This is the easiest way to get started with EOP data for most applications.

set_global_eop_provider¶

set_global_eop_provider `builtin` ¶

set_global_eop_provider(provider: StaticEOPProvider | FileEOPProvider | CachingEOPProvider) -> Any

Set the global EOP provider using any supported provider type.

This function accepts any of the three EOP provider types: StaticEOPProvider, FileEOPProvider, or CachingEOPProvider. This is the recommended way to set the global EOP provider.

Parameters:

Name	Type	Description	Default
`provider`	`StaticEOPProvider \| FileEOPProvider \| CachingEOPProvider`	EOP provider to set globally	required

Example

import brahe as bh

# Use with StaticEOPProvider
provider = bh.StaticEOPProvider.from_zero()
bh.set_global_eop_provider(provider)

# Use with FileEOPProvider
provider = bh.FileEOPProvider.from_default_standard(True, "Hold")
bh.set_global_eop_provider(provider)

# Use with CachingEOPProvider
provider = bh.CachingEOPProvider(
    eop_type="StandardBulletinA",
    max_age_seconds=7 * 86400,
    auto_refresh=False,
    interpolate=True,
    extrapolate="Hold"
)
bh.set_global_eop_provider(provider)

Set the global EOP provider using any supported provider type (StaticEOPProvider, FileEOPProvider, or CachingEOPProvider).

Querying Global EOP Data¶

get_global_eop¶

get_global_eop `builtin` ¶

get_global_eop(mjd: float) -> tuple[float, float, float, float, float, float]

Get all EOP parameters from the global EOP provider.

Parameters:

Name	Type	Description	Default
`mjd`	`float`	Modified Julian Date	required

Returns:

Type	Description
`tuple[float, float, float, float, float, float]`	tuple[float, float, float, float, float, float]: UT1-UTC, pm_x, pm_y, dx, dy, lod

Get all EOP values for a specific Modified Julian Date.

Returns: Tuple of (ut1_utc, pm_x, pm_y, dx, dy, lod)

get_global_ut1_utc¶

get_global_ut1_utc `builtin` ¶

get_global_ut1_utc(mjd: float) -> float

Get UT1-UTC time difference from the global EOP provider.

Parameters:

Name	Type	Description	Default
`mjd`	`float`	Modified Julian Date	required

Returns:

Name	Type	Description
`float`	`float`	UT1-UTC time difference in seconds

Get UT1-UTC offset in seconds.

get_global_pm¶

get_global_pm `builtin` ¶

get_global_pm(mjd: float) -> tuple[float, float]

Get polar motion components from the global EOP provider.

Parameters:

Name	Type	Description	Default
`mjd`	`float`	Modified Julian Date	required

Returns:

Type	Description
`tuple[float, float]`	tuple[float, float]: Polar motion x and y components in radians

Get polar motion (x, y) in radians.

get_global_dxdy¶

get_global_dxdy `builtin` ¶

get_global_dxdy(mjd: float) -> tuple[float, float]

Get celestial pole offsets from the global EOP provider.

Parameters:

Name	Type	Description	Default
`mjd`	`float`	Modified Julian Date	required

Returns:

Type	Description
`tuple[float, float]`	tuple[float, float]: Celestial pole offsets dx and dy in radians

Get celestial pole offsets (dx, dy) in radians.

get_global_lod¶

get_global_lod `builtin` ¶

get_global_lod(mjd: float) -> float

Get length of day offset from the global EOP provider.

Parameters:

Name	Type	Description	Default
`mjd`	`float`	Modified Julian Date	required

Returns:

Name	Type	Description
`float`	`float`	Length of day offset in seconds

Get length of day offset in seconds.

EOP Metadata¶

get_global_eop_type¶

get_global_eop_type `builtin` ¶

get_global_eop_type() -> str

Get the EOP data type of the global provider.

Returns:

Name	Type	Description
`str`	`str`	EOP type string

Get the type of global EOP provider ("file" or "static").

get_global_eop_initialization¶

get_global_eop_initialization `builtin` ¶

get_global_eop_initialization() -> bool

Check if the global EOP provider is initialized.

Returns:

Name	Type	Description
`bool`	`bool`	True if global EOP provider is initialized

Check if global EOP provider has been initialized.

get_global_eop_interpolation¶

get_global_eop_interpolation `builtin` ¶

get_global_eop_interpolation() -> bool

Check if interpolation is enabled in the global EOP provider.

Returns:

Name	Type	Description
`bool`	`bool`	True if interpolation is enabled

Check if interpolation is enabled.

get_global_eop_extrapolation¶

get_global_eop_extrapolation `builtin` ¶

get_global_eop_extrapolation() -> str

Get the extrapolation method of the global EOP provider.

Returns:

Name	Type	Description
`str`	`str`	Extrapolation method string

Get extrapolation method ("Hold", "Zero", or "Error").

get_global_eop_len¶

get_global_eop_len `builtin` ¶

get_global_eop_len() -> int

Get the number of EOP data points in the global provider.

Returns:

Name	Type	Description
`int`	`int`	Number of EOP data points

Get number of EOP data points in provider.

get_global_eop_mjd_min¶

get_global_eop_mjd_min `builtin` ¶

get_global_eop_mjd_min() -> float

Get the minimum Modified Julian Date in the global EOP dataset.

Returns:

Name	Type	Description
`float`	`float`	Minimum MJD

Get minimum (earliest) MJD in EOP data.

get_global_eop_mjd_max¶

get_global_eop_mjd_max `builtin` ¶

get_global_eop_mjd_max() -> float

Get the maximum Modified Julian Date in the global EOP dataset.

Returns:

Name	Type	Description
`float`	`float`	Maximum MJD

Get maximum (latest) MJD in EOP data.

get_global_eop_mjd_last_lod¶

get_global_eop_mjd_last_lod `builtin` ¶

get_global_eop_mjd_last_lod() -> float

Get the last Modified Julian Date with LOD data in the global provider.

Returns:

Name	Type	Description
`float`	`float`	Last MJD with LOD data

Get MJD of last LOD (Length of Day) data point.

get_global_eop_mjd_last_dxdy¶

get_global_eop_mjd_last_dxdy `builtin` ¶

get_global_eop_mjd_last_dxdy() -> float

Get the last Modified Julian Date with dx/dy data in the global provider.

Returns:

Name	Type	Description
`float`	`float`	Last MJD with dx/dy data

Get MJD of last dX/dY (celestial pole offset) data point.

Downloading EOP Files¶

download_standard_eop_file¶

download_standard_eop_file `builtin` ¶

download_standard_eop_file(filepath: str) -> Any

Download latest standard Earth orientation parameter file. Will attempt to download the latest parameter file to the specified location. Creating any missing directories as required.

The download source is the IERS Earth Orientation Data Products

Parameters:

Name	Type	Description	Default
`filepath`	`str`	Path of desired output file	required

Example

import brahe as bh

# Download latest standard EOP data
bh.download_standard_eop_file("./eop_data/standard_eop.txt")

download_c04_eop_file¶

download_c04_eop_file `builtin` ¶

download_c04_eop_file(filepath: str) -> Any

Download latest C04 Earth orientation parameter file. Will attempt to download the latest parameter file to the specified location. Creating any missing directories as required.

The download source is the IERS Earth Orientation Data Products

Parameters:

Name	Type	Description	Default
`filepath`	`str`	Path of desired output file	required

Example

import brahe as bh

# Download latest C04 EOP data
bh.download_c04_eop_file("./eop_data/finals2000A.all.csv")

Usage Examples¶

Quick Start (Recommended)¶

import brahe as bh

# Initialize EOP with recommended defaults - easiest way to get started!
bh.initialize_eop()

# Query EOP for specific epoch
epoch = bh.Epoch.from_datetime(2024, 1, 1, 0, 0, 0.0, 0.0, bh.TimeSystem.UTC)
mjd = epoch.mjd()

ut1_utc, pm_x, pm_y, dx, dy, lod = bh.get_global_eop(mjd)
print(f"EOP for MJD {mjd}:")
print(f"  UT1-UTC: {ut1_utc:.6f} s")
print(f"  Polar Motion: ({pm_x*1e6:.3f}, {pm_y*1e6:.3f}) μrad")
print(f"  dX, dY: ({dx*1e6:.3f}, {dy*1e6:.3f}) μrad")
print(f"  LOD: {lod*1e3:.6f} ms")

Custom Provider Setup¶

import brahe as bh

# Download and set up file-based EOP with custom settings
eop_file = bh.download_standard_eop_file("./data")
provider = bh.FileEOPProvider.from_standard_file(
    eop_file,
    interpolate=True,
    extrapolate="Hold"
)
bh.set_global_eop_provider(provider)

# Check provider status
print(f"EOP Type: {bh.get_global_eop_type()}")
print(f"Data points: {bh.get_global_eop_len()}")
print(f"Date range: MJD {bh.get_global_eop_mjd_min():.1f} to {bh.get_global_eop_mjd_max():.1f}")
print(f"Interpolation: {bh.get_global_eop_interpolation()}")
print(f"Extrapolation: {bh.get_global_eop_extrapolation()}")

EOP Functions¶

Setting Global EOP Provider¶

initialize_eop¶

initialize_eop builtin ¶

set_global_eop_provider¶

set_global_eop_provider builtin ¶

Querying Global EOP Data¶

get_global_eop¶

get_global_eop builtin ¶

get_global_ut1_utc¶

get_global_ut1_utc builtin ¶

get_global_pm¶

get_global_pm builtin ¶

get_global_dxdy¶

get_global_dxdy builtin ¶

get_global_lod¶

get_global_lod builtin ¶

EOP Metadata¶

get_global_eop_type¶

get_global_eop_type builtin ¶

get_global_eop_initialization¶

get_global_eop_initialization builtin ¶

get_global_eop_interpolation¶

get_global_eop_interpolation builtin ¶

get_global_eop_extrapolation¶

get_global_eop_extrapolation builtin ¶

get_global_eop_len¶

get_global_eop_len builtin ¶

get_global_eop_mjd_min¶

get_global_eop_mjd_min builtin ¶

get_global_eop_mjd_max¶

get_global_eop_mjd_max builtin ¶

get_global_eop_mjd_last_lod¶

get_global_eop_mjd_last_lod builtin ¶

get_global_eop_mjd_last_dxdy¶

get_global_eop_mjd_last_dxdy builtin ¶

Downloading EOP Files¶

download_standard_eop_file¶

download_standard_eop_file builtin ¶

download_c04_eop_file¶

download_c04_eop_file builtin ¶

Usage Examples¶

Quick Start (Recommended)¶

Custom Provider Setup¶

See Also¶

initialize_eop `builtin` ¶

set_global_eop_provider `builtin` ¶

get_global_eop `builtin` ¶

get_global_ut1_utc `builtin` ¶

get_global_pm `builtin` ¶

get_global_dxdy `builtin` ¶

get_global_lod `builtin` ¶

get_global_eop_type `builtin` ¶

get_global_eop_initialization `builtin` ¶

get_global_eop_interpolation `builtin` ¶

get_global_eop_extrapolation `builtin` ¶

get_global_eop_len `builtin` ¶

get_global_eop_mjd_min `builtin` ¶

get_global_eop_mjd_max `builtin` ¶

get_global_eop_mjd_last_lod `builtin` ¶

get_global_eop_mjd_last_dxdy `builtin` ¶

download_standard_eop_file `builtin` ¶

download_c04_eop_file `builtin` ¶