CL_tle_genEphem

Description

• Generates an ephemeris (osculating position and velocity) from TLEs.

  There can be 2 cases:

  - either there is only one element in the TLE structure and any number of propagation times,

  - or there are several elements and as many propagation times. In this case, each element in the TLE structure is propagated to the corresponding time.

  In a standard situation, the output position and velocity are converted to the specified reference frame. The input times are considered to be given in the TREF time scale and are converted to UTC internally (UTC as defined at TLE epoch). Note that if the frame is not a true equator frame, the transformation may not be as accurate as should be as the frame transformation arguments that can be provided are limited to ut1_tref and tt_tref.

  It is also possible to give frame a special value: "native". It means that reference frame AND time scale are supposed to be those natively used for TLEs: TEME and UTC repectively. No conversion is performed.

Parameters

tle:

TLE structure (size 1 or N)

cjd:

Propagation date (modified julian days from 1950.0, TREF time scale except if frame == "native") (1xN or 1x1)

frame:

Output frame, see above for details. Default is "ECI".

ut1_tref:

(optional) UT1-TREF [seconds]. Default is %CL_UT1_TREF (1xN or 1x1)

tt_tref:

(optional) TT-TREF [seconds]. Default is %CL_TT_TREF (1xN or 1x1)

pos:

Osculating position vector relative to the specified frame [m] (3xN)

vel:

Osculating velocity vector relative to the specified frame [m/s] (3xN)

Authors

• CNES - DCT/SB/MS

See also

• CL_tle_update

Examples

str = [.. "1 00005U 58002B 00179.78495062 .00000023 00000-0 28098-4 0 4753"; .. "2 00005 34.2682 348.7242 1859667 331.7664 19.3264 10.82419157413667" ]; tle = CL_tle_parse(str); cjd = round(tle.epoch_cjd) : round(tle.epoch_cjd)+5; // TREF [pos, vel] = CL_tle_genEphem(tle, cjd) // ECI