R: Prediction Starlink train position

From: Giuseppe via Seesat-l <seesat-l_at_satobs.org>
Date: Sun, 26 May 2019 05:23:51 +0000
image file: Starlink-from-Northern-Europe.png

________________________________
Da: Seesat-l <seesat-l-bounces+joematara=hotmail.com_at_satobs.org> per conto di Giuseppe via Seesat-l <seesat-l_at_satobs.org>
Inviato: domenica 26 maggio 2019 05:11
A: SeeSat-L_at_satobs.org
Oggetto: Prediction Starlink train position

One image of the video issued here http://www.satobs.org/seesat/May-2019/0234.html
has been uploaded in Miscellanea folder of my GitHub repo https://github.com/sunrise125/Satellites-Orbits/find/master
where the red marked satellite is trivial, just to figure out one of the
sixty bodies.

By introducing DateTime&Location data to the python code written below,
along with the TLE elements taken from http://www.satobs.org/seesat/May-2019/0207.html
we obtain such results:
-----------------------------------------
 Sat Name =  Starlink Train
 Sat Epoch=  2019-05-24 22:56:05.819423
 Sat Numb =  74001

 Prediction date:  2019 5 25
 Prediction time:  23 50 43  UTC

 Observer location: Lambda= 4.497 deg  Phi= 52.1601 deg  H= 4.0  m
 Azimuth  : -96.35896 deg
 Elevation: 12.74073 deg
 Distance : 1408.534 km
------------------------------------------

They seem acceptable, maybe elevation appear a bit low. Nevertheless the
accuracy can be enhanced when orbital elements refer to a single sat.

Cheers,
Giuseppe

# ---- azel_TLE.py ---------- May.25, 2019 ------
# Azimuth, elevation, distance froma TLE's elements
# Source: https://bwinkel.github.io/pycraf/satellite/index.html
import datetime
import numpy as np
from astropy.coordinates import EarthLocation
from astropy import time
from pycraf import satellite

# -------- 3-line TLE elements input -------------
tle_string = '''Starlink Train
1 74001U 19644A   19144.95562291  .00000000  00000-0  50000-4 0    06
2 74001  53.0084 171.3414 0001000   0.0000  72.1720 15.40507866    07'''

satname, sat = satellite.get_sat(tle_string)
print ('\n Sat Name = ', satname,'\n Sat Epoch= ', sat.epoch, '\n Sat Numb = ', sat.satnum)

# Datetime input
year=2019; month=5; day=25; utch=23; utcm=50; utcs=43
print ('\n Prediction date: ', year, month, day )
print (' Prediction time: ', utch, utcm, utcs, ' UTC' )
dt = datetime.datetime(year, month, day, utch, utcm, utcs)
obstime = time.Time(dt)

# define observer location
Lambda=4.4970; Phi=52.1601; H=4.0
location = EarthLocation(Lambda, Phi, H)
# create a SatelliteObserver instance
sat_obs = satellite.SatelliteObserver(location)
#
az, el, dist = sat_obs.azel_from_sat(tle_string, obstime)
print('\n Observer location: Lambda=', Lambda, 'deg  Phi=', Phi,  'deg  H=', H,' m')
print(' Azimuth  : {:.5f}'.format(az))
print(' Elevation: {:.5f}'.format(el))
print(' Distance : {:.3f}'.format(dist))
# EOF azel_TLE.py ----------


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Received on Sun May 26 2019 - 00:24:17 UTC

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