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Brahe CLI

The Brahe command-line interface provides tools for quick-access time, coordinate, and orbital mechanics calculations directly from the terminal. It also provides functions to download Earth Orientation Parameters (EOP) and satellite datasets.

Installation

The CLI is included with the Brahe Python package:

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pip install brahe
# or
uv pip install brahe

Quick Start

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# Get help
brahe --help

# Convert between time formats
brahe time convert "2024-01-01T00:00:00Z" string mjd
# 60310.00042824074

# Calculate orbital period
brahe orbits orbital-period "R_EARTH+500e3" --units minutes
# 94.616286

# Transform coordinates between representations
brahe transform coordinates keplerian cartesian "" 6878137 0.001 97.8 0 0 0 --as-degrees
# [6871258.863000, 0.000000, 0.000000, 0.000000, -1034.183142, 7549.721055

# Compute satellite access windows
brahe access compute 25544 --lon -122.4194 --lat 37.7749
# Access Windows for ISS (ZARYA) (NORAD ID: 25544)
# Location: 37.7749° lat, -122.4194° lon, 0 m alt
# Minimum elevation: 10.0°
# Found 17 access window(s)
# ...

Command Groups

eop

Earth Orientation Parameter operations: - download - Download EOP data from IERS - get-utc-ut1 - Get UTC-UT1 offset - get-polar-motion - Get polar motion parameters - get-cip-offset - Get CIP offset - get-lod - Get length of day

datasets

Download and query satellite data: - celestrak - CelesTrak TLE data operations - groundstations - Ground station database operations

time

Time system operations and conversions:

  • convert - Convert between time formats (MJD, JD, GPS, ISO-8601)
  • add - Add time offsets to epochs
  • time-system-offset - Calculate offsets between time systems
  • range - Generate time ranges

orbits

Orbital mechanics calculations:

  • orbital-period - Calculate orbital period from semi-major axis
  • sma-from-period - Calculate semi-major axis from period
  • mean-motion - Calculate mean motion
  • anomaly-conversion - Convert between anomaly types
  • sun-sync-inclination - Calculate sun-synchronous inclination
  • perigee-velocity / apogee-velocity - Calculate velocities at apsides

transform

Convert between coordinate systems and reference frames:

  • coordinates - Convert between Keplerian, Cartesian, Geodetic, and Geocentric representations

access

Satellite access window calculations: - compute - Calculate visibility windows for ground stations

Global Options

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--verbose, -v    Enable verbose output (INFO level)
--debug, -d      Enable debug output (DEBUG level)
--help           Show help message

Features

Constant Expressions

Many numeric arguments support mathematical expressions using Brahe constants:

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# Use R_EARTH constant for semi-major axis (500km altitude LEO)
brahe orbits orbital-period "R_EARTH+500e3" --units minutes
# 94.616286

Available constants include: - R_EARTH, R_SUN, R_MOON - Body radii (meters) - GM_EARTH, GM_SUN, GM_MOON - Gravitational parameters (m³/s²) - DEG2RAD, RAD2DEG - Angular conversions - MJD_ZERO, MJD2000, GPS_ZERO - Time epoch constants

See the Constants documentation for the complete list.

See Also