Observe a predicted satellite pass
Compare published orbit predictions with a visible or received pass. Log time, direction and signal changes across more than one passage.
What you need
- Public orbital-element record and pass predictions
- Clock and coordinates
- Camera, binoculars or a receive-only radio setup
Collect the readings
- Choose a satellite and retain the orbital-element epoch used for the prediction. Find a pass above your horizon. Do not substitute a prediction from a different observer location.
- For a visual pass, record the moving point relative to known stars with UTC times. For a radio pass, record the identifier and frequency while obeying local rules; this activity does not require transmitting.
- Compare acquisition, closest approach and loss times with the prediction. A received frequency can shift as the satellite approaches and recedes; keep receiver calibration and nominal transmit frequency distinct.
- Repeat on another pass before interpreting a mismatch. An old orbit record, obstructed horizon or mistaken object identification can change the comparison.
Compare the predictions
Visible motion and timed radio propagation can be compared with one orbital trajectory.
Orbit tracking adds an independent observable beyond a published photograph.
A single pass does not by itself determine every feature of Earth’s shape.
Open the related calculation →