Skyfield: Home • Table of Contents • API Reference
See Earth Satellites for an introduction to downloading Earth satellite data and computing their positions with Skyfield.
EarthSatellite(line1, line2, name=None, ts=None)¶
An Earth satellite loaded from a TLE file and propagated with SGP4.
An earth satellite object is a Skyfield vector function, so you can
either call its
at() method to generate its position in the sky
or else use addition and subtraction to combine it with other
Satellite parameters are generally only accurate for a week or two around the epoch of the parameters, the date for which they were generated, which is available as an attribute:
Timegiving the exact epoch moment for these satellite orbit parameters.
When building a satellite, use the arguments
to provide the two data lines from a TLE file as separate strings.
name lets you give a name to the satellite, accessible
later through the
ts is a
Timescale object, used to generate the
epoch value; if it is not provided, the satellite will use a
If you are interested in the catalog entry details, the SGP4 model
parameters for a particular satellite can be accessed through its
Build an EarthSatellite from a raw sgp4 Satrec object.
This lets you provide raw numeric orbital elements instead of the text of a TLE set. See Build a satellite from orbital elements for detais.
Return the ITRF position, velocity, and error at time
The position is an x,y,z vector measured in au, the velocity is
an x,y,z vector measured in au/day, and the error is a vector of
possible error messages for the time or vector of times
find_events(topos, t0, t1, altitude_degrees=0.0)¶
Return the times at which the satellite rises, culminates, and sets.
t1, which should each be a
Time object, for passes of
this satellite above the location
topos that reach at least
altitude_degrees above the horizon.
Returns a tuple
(t, events) whose first element is a
Time array and whose second element
is an array of events:
Note that multiple culminations in a row are possible when, without setting, the satellite reaches a second peak altitude after descending partway down the sky from the first one.