Two-Line Element (TLE) orbits(`pymgp.tleorb`)#

Compute satellite position and velocity using two-line elements available from Celestrak (https://celestrak.org).

Get and read NORAD Two Line Elements in TLE structure array#

`tleget`(tleset[, tlefile])	Retrieve NORAD Two Line Elements from www.celestrak.com.
`tleread`(tlefile[, verbose])	Read NORAD Two Line Elements from file.
`tleprint`(tle)	Print NORAD Two Line Elements.

Find satellites and select dates#

`tlefind`(tle, satid[, verbose])	Find named satellites in the NORAD Two Line Elements.
`tledatenum`(daterange)	Compute datenumber range from start date, end date and interval.

Compute satellite positions and orbit propagation#

`tle2orb`(tle, t[, propagation])	Compute satellite orbital elements from NORAD Two Line Elements.
`tle2vec`(tle, t, satid[, propagation, verbose])	Compute satellite position and velocity in ECI from NORAD Two Line Elements.

The functions are optimized for Python’s numpy library, it accepts mostly numpy alike ndarrays with the coordinates (usually three) in the last axis.

Notes#

The mean orbital elements in the two-line elements are Earth-centered-inertial (ECI) coordinates with respect to the true equator of date and the mean equinox of date. They do not include the effect of nutation. The tle’s are compatible with the SGP4 and SDP4 orbit propagators of NORAD.

The default orbit propagator used by this module is a simplified method that only includes the secular effects of J2. This gives acceptable results for plotting purposes and planning computations. The SGP4 and SDP4 methods are not implemented, anyway, for precise orbits the user should resort to other sources for satellite orbits

Examples#

Download tle data for Earth Resource Satellites

>>> tlefile = tleget('resource')
Saving TLE set to default name
TLEGET: Downloaded resource.txt from http://celestrak.com/NORAD/elements/
Saved TLE to resource.txt

Read tle data for Earth Resource Satellites from file (file downloaded on Aug 2, 2024) and compute the position and velocity of RADARSAT-2

>>> tleERS = tleread('resource-20240802.tle', verbose=0)
>>> xsat, vsat, *_ = tle2vec(tleERS,'2024-08-02 05:58:10','RADARSAT-2')
>>> print(xsat, vsat)
[[5458404.60763595 4591181.8357549  -732126.12944127]] [[  144.29836955 -1339.50959494 -7333.2677589 ]]

Compute RADARSAT-2 position and velocities for Aug 2, 2024, with one minute intervals

>>> xsat, vsat, t, *_ = tle2vec(tleERS,['2024-08-02 0:00', 24*60, 1],'RADARSAT-2')
>>> print(xsat.shape, vsat.shape, t.shape)
(1441, 3) (1441, 3) (1441,)

Position and velocity, on Aug 2, 2024, for every SENTINEL satellite, with one minute interval

>>> xsat, vsat, t, satids = tle2vec(tleERS,['2024-08-02 0:00', 24*60, 1],'SENTINEL')
>>> print(xsat.shape, vsat.shape, t.shape, satids.shape)
>>> print(satids)
(7, 1441, 3) (7, 1441, 3) (1441,) (7,)
['SENTINEL-1A' 'SENTINEL-2A' 'SENTINEL-3A' 'SENTINEL-2B' 'SENTINEL-5P'
 'SENTINEL-3B' 'SENTINEL-6']

Find satellites and set date range and interval (used for instance by tle2vec)

>>> isat, satids = tlefind(tleERS, 'SENTINEL', verbose=0)
print(isat, satids)
[ 65  87  99 116 122 133 148] ['SENTINEL-1A' 'SENTINEL-2A' 'SENTINEL-3A' 'SENTINEL-2B' 'SENTINEL-5P'
 'SENTINEL-3B' 'SENTINEL-6']

>>> t = tledatenum(['2024-08-02 0:00', 24*60, 1])
>>> print(t.shape)
(1441,)

References#

Celestrak web-site (https://celestrak.org)
NORAD GP Element Sets Current Data (https://celestrak.org/NORAD/elements/)

Two-Line Element (TLE) orbits(pymgp.tleorb)#