What is "sun outage"

n. An interruption in, or distortion of, geostationary satellite signals caused by interference from solar radiation

A Sun outage, Sun transit or Sun fade is an interruption in or distortion of geostationary satellite signals caused by interference from solar radiation. The effect is due to the Sun's radiation overwhelming the satellite signal.

In the northern hemisphere, sun outages occur before the March equinox (February, March) and after the September equinox (September and October), and in the southern hemisphere the outages occur after the March equinox and before the September equinox. At these times, the apparent path of the Sun across the sky takes it directly behind the line of sight between an Earth station and a satellite. The Sun radiates strongly across the entire spectrum, including the microwave frequencies used to communicate with satellites ( C-band, K band, and K band), so the Sun swamps the signal from the satellite. The effects of a Sun outage range from partial degradation (increase in the error rate) to total destruction of the signal. The effect sweeps from north to south from approximately 20 February to 20 April, and from south to north from approximately 20 August to 20 October, affecting any specific location for less than 12 minutes a day for a few consecutive days.