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NAVSTAR 51 (USA 166) — Live Satellite Tracking (NORAD 27663)
Track NAVSTAR 51 (USA 166) (NORAD catalog number 27663) live on the WatchSat interactive 3D globe above. Its position is propagated in real time from the latest CelesTrak two-line element set using the SGP4/SDP4 orbital model — the same math professional trackers run. It has been on orbit since 2003, launched on the 5th orbital launch of that year (COSPAR designation 2003-005A). As of this element set it had completed roughly 17,295 revolutions of Earth.
Moving at about 3.93 km/s, NAVSTAR 51 (USA 166) operates in medium Earth orbit at roughly 19,792–20,588 km altitude, taking about 12.0 hours per revolution (2.01 orbits a day). The orbit is essentially circular (eccentricity 0.0150). Inclined 54.9° to the equator, it overflies every latitude up to about 55° north and south. Its orbital plane crosses the equator northbound at right ascension 211.7°.
Orbital elements
| Orbit regime | medium Earth orbit (MEO) |
|---|---|
| Perigee × apogee altitude | ~19,792 km × 20,588 km |
| Inclination | 54.87° |
| Orbital period | 718.0 min (2.01 rev/day) |
| Eccentricity | 0.01500 |
| Element set epoch | 2026-09-06 |
| COSPAR designation | 2003-005A |
| NORAD catalog number | 27663 |
This page's orbital elements come from the CelesTrak catalog of 2026-09-08. The live 3D view above fetches its own current CelesTrak data when the page opens, through an edge cache that refreshes roughly every 30 minutes.
About the Navigation group
NAVSTAR 51 (USA 166) is part of the US GPS (NAVSTAR) fleet — one of 173 global-navigation satellites in the WatchSat catalog across GPS, GLONASS, Galileo and BeiDou. GNSS spacecraft broadcast precise time signals from orbits around 20,000 km up; a phone fixes its position by comparing several of them at once. See the whole navigation group live in 3D.
Can you see NAVSTAR 51 (USA 166) from the ground?
Not with the naked eye. At its altitude NAVSTAR 51 (USA 166) is far beyond unaided visibility — following satellites this high takes a telescope and good timing. You can still track it precisely in the live 3D view above, or check pass predictions for your location.
Related satellites
Nearest catalog neighbors of NAVSTAR 51 (USA 166) in the Navigation group — usually craft from the same or adjacent launches:
- NAVSTAR 52 (USA 168) (NORAD 27704)
- NAVSTAR 53 (USA 175) (NORAD 28129)
- NAVSTAR 54 (USA 177) (NORAD 28190)
- NAVSTAR 55 (USA 178) (NORAD 28361)
- NAVSTAR 56 (USA 180) (NORAD 28474)
- NAVSTAR 49 (USA 154) (NORAD 26605)
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