Satellite tracker for ISS (ZARYA) based on two line elements

Updated 03 Februrary 2014

20©01-20©10 Jens T. Satre

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Autoupdate time Manual update time

NOTE: This tracker uses a simplified calculation of satellite position which is NOT as accurate as trackers using SDP/SGP models !!
Two Line Elements:
Site Location  

Find your coordinates at GNS Search

Site Latitude Degrees

deg. min sec

Site Longitude Degrees

deg. min sec

Epoch time
Time elepsed since epoch hh:mm:ss
TLE data and time format
Julian Day
Modified Julian Day
Days since J2000.0
Hour (UTC)
Minute (UTC)
Second (UTC)
Time of calculation Local time
(if offset from UTC)
Satellite common name from TLE
Object Id from TLE
International Designator from TLE
Elset Classification from TLE
Number of orbits at Epoch from TLE
Number of orbits now
Earth Rev/solarday rev/day
Earth Deg/solarday deg/day
Earth Rev/siderealday rev/day
Earth Deg/siderealday deg/day
Satellite Deg/siderealday deg/day
Satellite Rev/sidereal rev/day (calculated for the time selected)
Satellite Deg/solarday deg/day
Epoch from TLE
Inclination deg from TLE
Right Ascension of Ascending node deg from TLE
Eccentricity from TLE
Argument of perigee deg from TLE
Mean anomaly, M0 deg at reference time (from TLE)
Mean anomaly Calculated deg calculated for time selected
True anomaly (v) deg
Mean Motion from TLE data rev/day (Satellite Rev/solarday) from TLE
Current Motion rev/day
1st derative of the Mean Motion rev/day^2 from TLE
Eccentric anomaly before iterations deg
Eccentric anomaly error before iterations deg
Eccentric anomaly after iterations deg
Eccentric anomaly error after iterations deg
Number of eccentric anomaly iterations
Xo orbital plane km
Yo orbital plane km
r orbital plane km
Geocentric, x km
Geocentric, y km
Geocentric, z km from equator
Right Ascension deg
GMST deg
Declination deg (current inclination)
Satellite E/W oscillation caused by inclination deg
Satellite E/W oscillation caused by eccentricity deg
Current Driftrate deg/day
Average Driftrate deg/day
Longitude Driftrate deg/day
Longitude after 24hours deg
Altitude km
from GEO now:
Average from GEO:
Altitude (Geodetic) km
Satellite period,TC hh:mm:ss
Nominal GEO period hh:mm:ss
Satellite velocity km/s
Altitude at Perigee km
Altitude at Apogee km
Semi-Major-Axis km
Semi-Minor-Axis km
Satellite Longitude deg
Satellite Geocentric Latitude deg
Satellite Geodetic Latitude deg
Satellite Azimuth deg
Satellite Elevation deg
Satellite Range km

Some sources of information used:

Johannes Kepler 1571-1630
Kepler's laws of planetary motion
M. Richharia - Satellite Communications Systems
Satellite Times Computers and Satellites
Two Line Elements - Space Track
Two Line Elements - Celestrak
View Earth from satellite
View Earth from satellite (example THOR 5)
Clarke Belt Snapshot Calculator (lists satellitte longitudes)
Heavens Above
C sourcecode example for TLE based orbit calculations
Paul Schlyters Stjarnhimlen
ORBITRON tracker (free)

20©01-20©08 Jens T. Satre