make_tle

ssapy.io.make_tle(a, e, i, pa, raan, trueAnomaly, t, drag_fields=None)[source][source]

Create a TLE from Kozai mean orbital elements

Parameters:

  • a (float) – Kozai mean semi-major axis in meters

  • e (float) – Kozai mean eccentricity

  • i (float) – Kozai mean inclination in radians

  • pa (float) – Kozai mean periapsis argument in radians

  • raan (float) – Kozai mean right ascension of the ascending node in radians

  • trueAnomaly (float) – Kozai mean true anomaly in radians

  • t (float or astropy.time.Time) – If float, then should correspond to GPS seconds; i.e., seconds since 1980-01-06 00:00:00 UTC

  • drag_fields (str, optional) – Line-1 columns 34-61 (ndot/2, nddot/6 and B*, 28 characters) to copy verbatim, e.g. line1[33:61] of the TLE an orbit came from. By default all three terms are written as zero.

Notes

Unless drag_fields is given, the dynamic TLE terms are zero. They used to be written with B* = ‘99999-0’, which SGP4 reads as 0.99999 per Earth radius: an enormous drag term for LEO (11,900 km of drift in 3 days).