asciiworld-sat-calc

#!/usr/bin/env python3


# Based on code and ideas of trehn's termtrack:
# https://github.com/trehn/termtrack


from math import acos, degrees

import datetime
import ephem
import sys


lines = sys.stdin.read().strip().splitlines()

sat = ephem.readtle(*lines)

sat.compute(datetime.datetime.utcnow())
lon = sat.sublong
lat = sat.sublat
ele = sat.elevation
print('points')
print('{:f} {:f}'.format(degrees(lat), degrees(lon)))
print('.')

print('track')
orbital_period = 60 * 60 * 24 / sat._n
orbit_offset = 0
while orbit_offset < orbital_period:
    orbit_offset += orbital_period / 150
    sat.compute(datetime.datetime.utcnow() +
            datetime.timedelta(seconds=orbit_offset))
    print('{:f} {:f}'.format(degrees(sat.sublat), degrees(sat.sublong)))
print('.')

print('track')
orbit_offset = 0
while orbit_offset > -0.05 * orbital_period:
    orbit_offset -= orbital_period / 150
    sat.compute(datetime.datetime.utcnow() +
            datetime.timedelta(seconds=orbit_offset))
    print('{:f} {:f}'.format(degrees(sat.sublat), degrees(sat.sublong)))
print('.')

if not (len(sys.argv) > 1 and sys.argv[1] == '-F'):
    # The satellite's footprint is a small circle centered at (lat, lon)
    # with radius r (spherical distance).
    print('circles')
    r_earth = 6371000
    try:
        r = acos(r_earth / (r_earth + ele))
        print('{:f} {:f} {:f}'.format(degrees(lat), degrees(lon), degrees(r)))
    except ValueError:
        print('Something is wrong with the elevation of the satellite: {}'.format(ele),
              file=sys.stderr
        )
    print('.')