Satellite Tracker

Input

Tutorial, 5 steps

Set your observer latitude, longitude, and height, or use Use my location or click either projection map.
Pick a satellite from the catalog or a quick preset such as ISS or SES-1.
Choose a predicted pass from the pass picker when more than one rise → peak → set window is available.
Scrub the replay slider, the sky-dome marker and satellite ground-track marker move together on the same SGP4 geometry.
Compare globe or map against the Flat Earth disc: the ground track is identical; only the projection changes. Copy the share link to restore pass and replay position.

Quick picks load a known NORAD catalog number. Use the satellite selector below for stations, visual objects, or any custom catalog ID.

Observer

Set the viewing location used for pass replay and horizon geometry.

Observer latitudeObserver longitudeObserver height (m)

Observer helpers

Use browser geolocation or click either projection map below to move the observer.

Satellite selection

Choose the source catalog and the tracked object.

Satellite sourceSatelliteNORAD catalog number

Time and projection

Choose the search window and the left-hand comparison projection.

Window startLeft comparisonSearch window (hours)

Open pass predictor Orbit primer

No TLE records returned from CelesTrak NORAD 25544.

What This Tool Shows

What This Tool Debunks

"Satellites are balloons or towers that cannot reproduce repeatable rise, peak, and set geometry."

Visibility Graphic

Azimuth,

Elevation,

Range,

Orbit height,

Sunlit fraction,

Left: globe or standard map. Right: Flat Earth Azimuthal Equidistant disc. The same server-calculated ground track and live satellite sub-point are rendered on both, so the only difference is projection geometry.

Left comparison: Globe (3D)

Right comparison: Flat Earth (Azimuthal Equidistant)

Track window: Waiting for a valid pass replay
Scrub the pass replay slider to move the satellite marker along the same ground track on both projections.
Click either projection to move the observer and recompute passes from that location.

Evidence Card

Claim

Scrubbing a TLE-driven pass on the globe reproduces rise, peak, set, and elevation above the horizon mask for ISS and geostationary examples.

Model Used

SGP4 propagation with topocentric elevation and sub-satellite ground track on a spherical Earth.

Formula

T=2π √(R + h)³ / GM

d_slant=√2Rh + h²

GEO=≈ 1 sidereal day at ~35,786 km

Last Verified

2026-03-23

Assumptions

Preset NORAD catalog numbers use current CelesTrak TLE lines for the selected window.
Horizon mask uses 0° elevation; refraction and terrain are not included.

External Sources

What Would Falsify This Page

A repeatable pass replay where elevation and ground track disagreed with SGP4 for the same TLE would count against this page.

Sources

CelesTrak: Current GP Element Sets: Official source for current TLE and OMM satellite element sets used by the pass predictor.
CelesTrak: Stations TLE feed: Live TLE feed for ISS-class and station objects, useful for bright naked-eye passes.
satellite.js docs: Library docs for SGP4 propagation, look angles, and shadow fraction calculations.
ESA: How satellite navigation works: Neutral overview of navigation-satellite line-of-sight geometry.
ESA: Galileo, a constellation of navigation satellites: Reference altitude and constellation facts for real navigation satellites in orbit.
NOAA NGS: Geodesy Fundamentals: Covers geodesy, map projections, and GPS from a neutral surveying perspective.

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