Jonathan C. McDowell

Illuminated Satellites

Section 6 Illuminated satellites versus time of night (2020 Calculations)

These plots show the number of illuminated satellites visible from a given location versus local time. A satellite is considered illuminated if the satellite-sun vector does not intersect the Earth. We simulate two cases, winter and summer, and consider both all satellites above the horizon and those with elevations above 30 degrees (corresponding to airmass 2, and to regions of the sky likely to be targets in most astronomical observations).

The blue line shows the total number of satellites, which is the sum of contributions from layer A (red), layer B (magenta), and layer C (green). See Section 2 for definitions of layers for each model.

Vertical black lines indicate local times where the sun is 0, 6, and 12 degrees below the horizon.

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