r2s2

r2s2 is a cislunar space-time coordinate transformation library supporting conversions between various coordinate systems.

Main Features

Space-Time Coordinate Conversion: Supports conversion between common cislunar coordinate systems
Time System Conversion: TT, TAI, UTC, UT1 and other time systems
Epoch Conversion: Julian Date, Modified Julian Date, time tags
Coordinate System Definitions: J2000, EME2000, ICRF, etc.

Installation

pip install r2s2

Supported Coordinate Systems

Coordinate System	Description
J2000	J2000.0 Mean Equator Coordinate System
EME2000	Earth Mean Equator 2000
ICRF	International Celestial Reference Frame
LVLH	Local Vertical Local Horizontal
RTN	Radial-Tangential-Normal

Supported Time Systems

Time System	Description
TT	Terrestrial Time
TAI	International Atomic Time
UTC	Coordinated Universal Time
UT1	Universal Time
JD	Julian Date
MJD	Modified Julian Date

Example Usage

import r2s2
from r2s2 import TimeSystem, CoordinateSystem

# Time conversion
jd = r2s2.tt_to_jd(tt_time)
utc_time = r2s2.jd_to_utc(jd)

# Coordinate conversion
state_eci = [7000, 0, 0, 0, 7.5, 0]  # km, km/s
state_lvlh = r2s2.eci_to_lvlh(state_eci, position, velocity)

# Batch conversion
times = [jd, jd + 0.5, jd + 1.0]
states_eci = [...]  # ECI coordinate states
states_rtln = r2s2.batch_transform(times, states_eci, 
                                   CoordinateSystem.ECI, 
                                   CoordinateSystem.RTN)

Resources

r2s2 GitHub Repository