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I would like to pull and parse the data for individual satellites from the TLE files at celestrak.com using Python. I found code to do so with pyephem using "readtle" but this does not work in skyfield. How can I pull the data from the tle files in skyfield?

pyephem is essentially deprecated. So, new to pyephem/skyfield, I have chosen to use skyfield.

I am trying to automatically pull the TLE information from the files at celestrak.com. I found code from several years ago that did so using pyephem under python 2.x.x. So, I am converting the code to Python 3.7.x.

However, the readtle aspect of the code used to pull the individual entries from the TLE files will not work on skyfield. I am accessing the files from the celestrak.com server.

I tried also to install pyephem, but obtained errors. And, I would like to stay with skyfield in any case.

The code I found reads:

class Satellite:
    def __init__(self, name, l1, l2):
        self.e        = ephem.readtle(name, l1, l2)
    def compute(self):
        self.e.compute(datetime.datetime.utcnow())
        self.long   = math.degrees(float(self.e.sublong))
        self.lat    = math.degrees(float(self.e.sublat))
        self.height = abs(int(self.e.elevation))
        r = 6378150 + self.height
        self.r = r / 1000000.0
        self.x      = -cos(radians(self.lat)) * cos(radians(self.long)) * self.r
        self.y      = sin(radians(self.lat)) * self.r
        self.z      = cos(radians(self.lat)) * sin(radians(self.long)) * self.r
        self.vlists  = sat_shape
        self.label = pyglet.text.Label(self.e.name, y=15, anchor_x="center", color=(255,255,255,200))

    def draw(self):
        glLoadIdentity()
        glTranslatef(0,0,-zoom+6.37815)
        glRotatef(ro, 1, 0, 0)
        glRotatef(rocc, 0, 0, 1)
        glTranslatef(0,0,-6.37815)
        glRotatef(-angle_y, 1, 0, 0)
        glRotatef(angle_x, 0, 1, 0)
        glTranslatef(self.x,self.y,self.z)
        glColor3f(1,0,0)
        glScalef(zoom/100.0, zoom/100.0, zoom/100.0)
        for v in self.vlists:
            v.draw(GL_TRIANGLE_STRIP)
        glScalef(0.02, 0.02, 0.02)
        glRotatef(-angle_x, 0, 1, 0)
        glRotatef(angle_y, 1, 0, 0)
        glRotatef(-rocc, 0, 0, 1)
        glRotatef(-ro, 1, 0, 0)
        self.label.draw()
        self.draw_line()

Does anyone have any ideas?

Valentino
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spacelaw
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1 Answers1

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Yes, you can use the loader of Skyfield to load the TLE file directly from Celestrak:

from skyfield.api import Topos, load
    
stations_url = 'http://celestrak.com/NORAD/elements/stations.txt'
satellites = load.tle(stations_url)
satellite = satellites['ISS (ZARYA)']
print(satellite)

EarthSatellite 'ISS (ZARYA)' number=25544 epoch=2014-01-20T22:23:04Z

More information is available in the documentation.

rfkortekaas
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