Quickstart

Installation

Ephemerista is distributed on PyPI and can be installed via pip.

# Create new virtual environment
python -m venv .venv
source .venv/bin/activate

# Install Ephemerista
pip install ephemerista

Obtain Required Data

Ephemerista requires the following data at runtime:

• Earth orientation parameters from the IERS: finals2000A.all.csv

• Planetary ephemerides in SPK format, e.g. de44s.bsp

• An Orekit data package: orekit-data-master.zip

  • Alternatively, the Orekit data can be installed as a Python package via pip, see here.

Initialise Ephemerista

Call the ephemerista.init function before using any other Ephemerista functionality and provide the paths to the required data files.

import ephemerista

EOP_PATH = ... # e.g. finals2000A.all.csv
SPK_PATH = ... # e.g. de440s.bsp
OREKIT_DATA_PATH = ... # e.g. orekit-data-master.zip

ephemerista.init(eop_path=EOP_PATH, spk_path=SPK_PATH, orekit_data=OREKIT_DATA_PATH)

If the Orekit data package was installed via package manager the orekit_data parameter can be omitted.

Use Ephemerista

Propagate the orbit of the ISS with Ephemerista.

import ephemerista
from ephemerista.propagators.sgp4 import SGP4
from ephemerista.time import TimeDelta

# Propgate the trajectory
iss_tle = """ISS (ZARYA)
1 25544U 98067A   24187.33936543 -.00002171  00000+0 -30369-4 0  9995
2 25544  51.6384 225.3932 0010337  32.2603  75.0138 15.49573527461367"""

propagator = SGP4(tle=iss_tle)
start_time = propagator.time
end_time = start_time + TimeDelta.from_hours(6)
times = start_time.trange(end_time, step=float(TimeDelta.from_minutes(1)))
trajectory = propagator.propagate(times)