The TLE structure

When a TLE is parsed using this package, the information is encapsulated in the structure TLE. Its fields are:

• name::String: Name of the satellite.
• satellite_number::Int: Satellite catalog number, in the interval [0, 339999]. Numbers above 99999 are written using the Alpha-5 scheme.
• classification::Char: Classification ('U', 'C', or 'S').
• international_designator::String: International designator, with at most 8 characters.
• epoch_year::Int: Epoch year (two digits). Years from 57 to 99 refer to the 20th century, and years from 0 to 56 to the 21st century.
• epoch_day::Float64: Epoch day (day + fraction of the day), in the interval [0, 367).
• dn_o2::Float64: 1st time derivative of mean motion / 2 [rev/day²].
• ddn_o6::Float64: 2nd time derivative of mean motion / 6 [rev/day³].
• bstar::Float64: B* drag term [1/ER].
• ephemeris_type::Int: Ephemeris type (one digit).
• element_set_number::Int: Element set number, in the interval [0, 9999].
• inclination::Float64: Inclination [deg].
• raan::Float64: Right ascension of the ascending node [deg].
• eccentricity::Float64: Eccentricity [ ], in the interval [0, 1).
• argument_of_perigee::Float64: Argument of perigee [deg].
• mean_anomaly::Float64: Mean anomaly [deg].
• mean_motion::Float64: Mean motion [rev/day], in the interval [0, 100).
• revolution_number::Int: Revolution number at epoch [rev], in the interval [0, 99999].

Notice that we preserve the units of the TLE definition. The constructor validates that every field can be represented in the fixed-width TLE format, throwing an ArgumentError otherwise. Hence, writing a TLE never fails.

Besides the fields, the property epoch returns the TLE epoch as a DateTime:

julia> using SatelliteToolboxTle
julia> tle = tle"""
           AMAZONIA 1
           1 47699U 21015A   23083.68657856 -.00000044  10000-8  43000-4 0  9990
           2 47699  98.4304 162.1097 0001247 136.2017 223.9283 14.40814394108652
           """TLE: AMAZONIA 1 (Epoch = 2023-03-24T16:28:40.388):
  ├─ Line 1
  │    Satellite Number         : 47699
  │    Classification           : U
  │    International Designator : 21015A
  │    Epoch Year               : 23
  │    Epoch Day                : 83.68657856
  │    ṅ/2                      : -4.4e-7 rev/day²
  │    n̈/6                      : 1.0e-9 rev/day³
  │    B*                       : 4.3e-5 1/ER
  │    Ephemeris Type           : 0
  │    Element Set Number       : 999
  └─ Line 2
       Inclination              : 98.4304°
       RA of the Ascending Node : 162.1097°
       Eccentricity             : 0.0001247
       Arg. of Perigee          : 136.2017°
       Mean Anomaly             : 223.9283°
       Mean Motion              : 14.40814394 rev/day
       Revolution Number        : 10865
julia> tle.epoch2023-03-24T16:28:40.388