ISC-11 // Satellite Operations
Sun Outage Predictor
Twice a year, around the equinoxes, the Sun passes behind each GEO satellite as seen from your antenna and floods the receiver with noise. Pick a ground station and dish, and this predicts the outage days, daily windows and expected C/N loss for every satellite in the shared ISC-11 fleet.
Outage calendar
Bar height is the daily outage duration. The Sun marks each satellite's worst day. Select a bar to see that satellite's daily times.
Season summary
How this is calculated
For each satellite the tool steps through both equinox seasons, computing the angle between the satellite and the centre of the Sun as seen from the ground station. Positions come from SGP4 on the shared TLE, or from the nominal orbital slot (on the equator at 42,164 km). The solar position uses the Astronomical Almanac low-precision ephemeris, good to about 0.01°. Close approaches are refined to a few seconds.
Half-power beamwidth is estimated as 70λ/D. The antenna noise increase treats the Sun as a uniform disk (apparent radius about 0.27°) seen through a Gaussian beam. The default Sun brightness temperature is a quiet-Sun estimate, 120,000·f−0.75 K with f in GHz; solar activity can raise it considerably, so treat C/N figures as indicative.
TLE propagation is only reliable for a couple of weeks around the TLE epoch for station-kept GEO satellites, which is why Auto mode uses the nominal slot for seasons far from the epoch. Real outage windows also depend on the satellite's position within its station-keeping box and on the actual antenna pattern, so allow a minute or so of margin either side.