cleanup

README.md

@@ -118,12 +118,15 @@ Spice TLE:
 
 * https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/FORTRAN/spicelib/evsgp4.html
 
-## pyorbital
-Orbital and astronomy computations in python.
+## SGP4
+SPG4
 
-* https://github.com/pytroll/pyorbital/
+*  https://pypi.org/project/sgp4/
 
-* https://pyorbital.readthedocs.io/
+## Skyfield
+Skyfield
+
+* https://rhodesmill.org/skyfield/earth-satellites.html
 
 
 # 3D Models

tle2ssc

@@ -7,67 +7,61 @@
 # Example:
 # tle2ssc foo-tle.txt
 
-# Check:
-# https://pypi.org/project/sgp4/
-# https://rhodesmill.org/skyfield/earth-satellites.html
-# https://github.com/ivanstan/tle-api
-# https://github.com/TruSat/trusat-orbit
-
 import os
 import skyfield
 import math
 from datetime import datetime
-from skyfield.api import load, wgs84
-from skyfield.api import EarthSatellite
+from skyfield.api import EarthSatellite, load, wgs84
 from sgp4.api import Satrec, WGS72
 
-satnum=37846
-satradius=0.005
-satname = 'GSAT0101'
-#satellites_url = 'http://celestrak.com/NORAD/elements/galileo.txt'
-satellites_url = './extras/galileo-gnss/galileo.txt'
-satellites = load.tle_file(satellites_url)
-#print('Loaded', len(satellites), 'satellites')
-
-ts = load.timescale()
-#t = ts.now()
-# 2022-05-20 02:17:30
-t = ts.utc(2022, 5, 20, 2, 17, 30)
-
 xpdotp = 1440.0 / (2.0 * math.pi)
 
+# For now dev with just one Galileo satellite
+satellite_name='GSAT0101'
+satellite_number=37846
+
+#satellites_url = 'http://celestrak.com/NORAD/elements/galileo.txt'
+satellites_url = './extras/galileo-gnss/galileo.txt'
+satellites = load.tle_file(satellites_url)
+
+ts = load.timescale()
+t = ts.now()
+# 2022-05-20 02:17:30
+#t = ts.utc(2022, 5, 20, 2, 17, 30)
+
 by_number = {sat.model.satnum: sat for sat in satellites}
-satellite = by_number[satnum]
+satellite = by_number[satellite_number]
 
-# Two different ways to get Epoch...
-#satepoch=(t.tdb)
-satepoch=satellite.model.jdsatepoch
-
-satellite_name=satname
-satellite_radius=satradius
-satellite_epoch=satepoch
-# ALLLLL XXX
+satellite_radius=0.005
+satellite_epoch=satellite.model.jdsatepoch
 #    The unique satellite NORAD catalog number given in the TLE file.
-satellite_number=satellite.model.satnum
+# Use one defined above.
+#satellite_number=satellite.model.satnum
+
 #    Satellite classification, or else 'U' for “Unknown”
 satellite_classification=satellite.model.classification
+
 #    International designator
 satellite_intldesg=satellite.model.intldesg
+
 #    Full four-digit year of this element set’s epoch moment.
 satellite_epochyr=satellite.model.epochyr
+
 #    Fractional days into the year of the epoch moment.
 satellite_epochdays=satellite.model.epochdays
+
 #    Julian date of the epoch (computed from epochyr and epochdays).
 satellite_jdsatepoch=satellite.model.jdsatepoch
+
 #    First time derivative of the mean motion (ignored by SGP4).
 satellite_ndot=satellite.model.ndot
-#print('satellite_ndot', satellite_ndot)
+
 #    Second time derivative of the mean motion (ignored by SGP4).
 satellite_nddot=satellite.model.nddot
-#print('satellite_nddot', satellite_nddot)
+
 #    Ballistic drag coefficient B* in inverse earth radii.
 satellite_bstar=satellite.model.bstar
-#print('satellite_bstar', satellite_bstar)
+
 #    Ephemeris type (ignored by SGP4 as determination now automatic)
 satellite_ephtype=satellite.model.ephtype
 #    Element number
@@ -75,6 +69,8 @@ satellite_elnum=satellite.model.elnum
 
 #    Inclination in radians. Convert radians to degrees.
 satellite_inclination=math.degrees(satellite.model.inclo)
+
+# Satellite Inclination and Obliquity are the same
 satellite_obliquity=math.degrees(satellite.model.inclo)
 
 #    Right ascension of ascending node in radians. Convert to degrees.
@@ -100,49 +96,6 @@ satellite_revnum=satellite.model.revnum
 # SemiMajor Axis
 satellite_semimajor_axis=pow((pow(satellite_period,2) * 75371000000000),0.33333333)
 
-#    'i',             # 'a' = old AFSPC mode, 'i' = improved mode
-#    5,               # satnum: Satellite number
-#    18441.785,       # epoch: days since 1949 December 31 00:00 UT
-#    2.8098e-05,      # bstar: drag coefficient (/earth radii)
-#    6.969196665e-13, # ndot: ballistic coefficient (revs/day)
-#    0.0,             # nddot: second derivative of mean motion (revs/day^3)
-#    0.1859667,       # ecco: eccentricity
-#    5.7904160274885, # argpo: argument of perigee (radians)
-#    0.5980929187319, # inclo: inclination (radians)
-#    0.3373093125574, # mo: mean anomaly (radians)
-#    0.0472294454407, # no_kozai: mean motion (radians/minute)
-#    6.0863854713832, # nodeo: right ascension of ascending node (radians)
-
-
-# Create SSC
-# From TLE:
-# GSAT0101 (PRN E11)      
-# 1 37846U 11060A   22140.09549104 -.00000093  00000+0  00000+0 0  9998
-# 2 37846  56.9858  22.1062 0004117  28.0726 331.9949  1.70474933 65739
-
-# Satellite name: GSAT0101
-# Satellite number: 37846U
-# Satellite number: 37846
-# International designator: 11060A
-# Inclination: 56.9858
-# Epoch year and Julian day fraction: 22140.09549104
-# Right ascension of ascending node: 22.1062
-# Eccentricity: 0004117
-# First derivative of mean motion or ballistic coefficient: -.00000093
-# Argument of perigee: 28.0726
-# Second derivative of mean motion: 00000+0
-# Mean anomaly: 331.9949
-# Drag term or radiation pressure coefficient: 00000+0
-# Mean motion: 1.70474933
-# Ephemeris type: 0
-# Element number and checksum: 9998
-# Revolution number at epoch and checksum: 65739
-
-
-# Convert epoch from TLE to SSC
-# Convert TLE to Julian Day
-# C47 = Epoch Year = 2022
-# =1721424.5-INT((C47-1)/100)+INT((C47-1)/400)+INT(365.25*(C47-1))+C49
 print('"', satellite_name, '-', satellite_number, '" ','"Sol/Earth" {',sep="")
 print('    Class "spacecraft"')
 print('    # Mesh "foo.3ds XXX"')