NORAD TLE
A standardised two-line data format published by NORAD/US Space Force that encodes the orbital elements of an Earth-orbiting object for use in satellite tracking software.
Full Definition
A NORAD Two-Line Element set (TLE) is a standardised ASCII format comprising two 69-character lines that encode the mean orbital elements — including inclination, right ascension, eccentricity, argument of perigee, mean anomaly, and mean motion — for a catalogued Earth-orbiting object. TLEs are the primary input data for ground-station antenna pointing and scheduling systems, allowing operators to predict satellite position and visibility windows. They are published and maintained by the US Space Force's 18th Space Control Squadron and are publicly accessible via Space-Track.org. Editors should render the acronym as 'TLE' (uppercase) and may optionally expand it as 'two-line element set' on first use. 'NORAD TLE' is the common colloquial designation; the formal product is simply 'TLE'.
Usage
Usage note: Expand 'TLE' as 'two-line element set' (lowercase) on first mention in formal documents. Do not write 'two-line elements' without 'set'. Distinguish from an 'ephemeris', which is a time-stamped table of precise state vectors and is more accurate than a TLE.
In Context
- "The antenna control unit ingests the latest NORAD TLE to compute the satellite's pass schedule for the next 24 hours." — Operations Manual
- "Engineers noted that TLEs older than seven days may introduce pointing errors exceeding the antenna's beamwidth for LEO satellites." — Technical Bulletin