115 lines
3.2 KiB
Python
Executable File
115 lines
3.2 KiB
Python
Executable File
#!/usr/bin/env python3
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"""
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Script showing the position of the ISS at the time of the TLE
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and the ground track for the previous and the next orbit
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(original) source: https://github.com/galactics/beyond/blob/master/doc/source/_static/ground-track.py
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"""
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import sys
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import argparse
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import numpy as np
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import matplotlib.pyplot as plt
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from pathlib import Path
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from beyond.dates import Date, timedelta
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from utils import tle_from_file
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if __name__ == "__main__":
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# Parse arguments
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parser = argparse.ArgumentParser(
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description="Plot the ground track of a TLE")
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parser.add_argument('TLEFILE', help="the tle file", type=str)
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args = parser.parse_args()
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# Parsing of TLE
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tle, name = tle_from_file(args.TLEFILE)
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# Conversion into `Orbit` object
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orb = tle.orbit()
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# Tables containing the positions of the ground track
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latitudes, longitudes = [], []
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prev_lon, prev_lat = None, None
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period = orb.infos.period
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# start = orb.date - period
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start = Date.now()
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stop = period
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step = period / 100
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for point in orb.ephemeris(start=start, stop=stop, step=step):
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# Conversion to earth rotating frame
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point.frame = 'ITRF'
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# Conversion from cartesian to spherical coordinates (range, latitude, longitude)
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point.form = 'spherical'
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# Conversion from radians to degrees
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lon, lat = np.degrees(point[1:3])
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# Creation of multiple segments in order to not have a ground track
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# doing impossible paths
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if prev_lon is None:
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lons = []
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lats = []
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longitudes.append(lons)
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latitudes.append(lats)
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elif orb.i < np.pi /2 and (np.sign(prev_lon) == 1 and np.sign(lon) == -1):
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lons.append(lon + 360)
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lats.append(lat)
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lons = [prev_lon - 360]
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lats = [prev_lat]
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longitudes.append(lons)
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latitudes.append(lats)
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elif orb.i > np.pi/2 and (np.sign(prev_lon) == -1 and np.sign(lon) == 1):
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lons.append(lon - 360)
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lats.append(lat)
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lons = [prev_lon + 360]
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lats = [prev_lat]
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longitudes.append(lons)
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latitudes.append(lats)
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lons.append(lon)
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lats.append(lat)
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prev_lon = lon
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prev_lat = lat
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fig = plt.figure(figsize=(15.2, 8.2))
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ax = fig.add_subplot(111)
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ax.set_title(start.datetime.strftime('%Y-%m-%dT%H:%M:%SZ'))
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# Plot earth
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img = Path(__file__).parent / "earth.png"
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im = plt.imread(str(img))
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ax.imshow(im, extent=[-180, 180, -90, 90])
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# Plot ground track
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for lons, lats in zip(longitudes, latitudes):
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ax.plot(lons, lats, 'r-')
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# Plot current location
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ax.plot(lons[0], lats[0], 'bo')
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# Plot location at epoch
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# lon, lat = np.degrees(orb.copy(frame='ITRF', form='spherical')[1:3])
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# ax.plot([lon], [lat], 'bo')
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ax.set_xlim([-180, 180])
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ax.set_ylim([-90, 90])
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ax.grid(True, color='w', linestyle=":", alpha=0.4)
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ax.set_xticks(range(-180, 181, 30))
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ax.set_yticks(range(-90, 91, 30))
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fig.tight_layout()
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if "no-display" not in sys.argv:
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plt.show()
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