Element Symbol Value
Epoch to 05:54:21.171 UTC December 16, 2007
Inclination i 51o.9970
R.A. of the Ascending Node aW0 251o.0219
Eccentricity e 0.0001492
Argument of Perigee w0 33o.8641
Mean Anomaly at TLE Epoch Mo 326o.2322
Mean Motion n 12.62256095 orbits / solar day
Propagation Time Dt 1.7677141 solar days
Mean Anomaly at Time t M(t) 1.37777389 radians (78o.940629)
True Anomaly at Time t n(t) 78o.95065818
Semi-major Axis a 7791.787473 km
Perigee Distance P 7790.624938 km
Geocentric Distance r(t) 7791.564499 km
Precessed R.A. of Asc. Node aW(t) 245o.6400244
Precessed Arg. of Perigee w(t) 37o.77767416
Argument of Latitude m(t) 116o.7283323
R.A. Difference Da 129o.278845
Geocentric R.A. ag 14o.9188694
Geocentric Declination dg +44o.73125163
Geocentric Cartesian x xg 5348.663965 km
Geocentric Cartesian y yg 1425.05581 km
Geocentric Cartesian z zg 5483.565179 km

Because satellites are much closer than most celestial objects astronomers observe, they will be seen in different parts of the sky from difference vantage points on the surface of the Earth. To predict where a satellite will be observed in your night sky, your observing location on the Earth must be known.

The observing location of the GlobalStar M047 satellite at time t0 was Brockville, Ontario Canada at the following coordinates:

Longitude = q = -75o.6883 (West is Negative)
Latitude =
l = +44o.5903 (North is Positive)

The Longitude and Latitude of a location on the Earth are in a convention called "Earth Center Fixed" (ECF). This indicates that no matter where you are on the Earth as it rotates, your longitude and latitude coordinates remain fixed. This is very convenient for locating objects on the Earth, but not convenient for locating objects in space. In order to perform the coordinate translation, we must transform the observer's longitude and latitude to the "Earth Center Inertial" (ECI); the convention used by the Equatorial Coordinate System.

Fortunately, the ECI Latitude of a location on the Earth is nearly the same as its ECF Latitude. In other words, the observer's Latitude on the Earth is nearly the same as the Declination of the same location as viewed from the center of the Earth. For this example, we will treat them as equal:

di = l

di = +44o.5903







Step 11: Choosing a Location Was Last Modified On April 01, 2014