Correlations of Starlink Satellite Flaring with UAP Observations

All-domain Anomaly Resolution Office (AARO)
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the Sun and the Earth’s surface at the horizon as viewed from an observer’s position on the earth.
During the day, solar altitude is a positive number expressed in degrees above the horizon. Solar
altitude is negative at night, expressed in degrees below the horizon. Solar azimuth describes the
angle to the Sun as referenced from true North at the observer’s position, e.g., 90° being due East
and 270° being due West. Seasonal changes affect the measurement of solar azimuth because of
the Earth's 23.5° axial tilt. In the northern hemisphere, the Sun appears to rise and set further north
each day between the winter and summer solstices. After the summer solstice, this cycle reverses,
and the Sun rises and sets further south each day until the winter solstice. Thus, the specific
azimuths of the rising and setting Sun are also dependent on the observer’s latitude [13]. There are
many online resources that will calculate the Sun’s altitude and azimuth at a given time and date
for a specific observer’s location expressed in latitude and longitude [14] [15]. Similarly, the
satellite’s altitude with respect to an observer’s position can be represented by an angle above the
horizon. This look angle is the elevation angle from the horizon to the observation point in the sky,
i.e., the point in the sky to potentially see flares. These geometries are shown in Figure 9.
The following calculations provide a guide to help observers predict when and where they might
be able to view a satellite flare in the night sky. This is an approximate mathematical treatment
and meant to be a guideline good to within a few degrees to help the observer estimate the look
angles and times for Starlink flares.
Figure 9: Cartoon of Sun’s altitude and azimuth as referenced to the location of an observer on
the Earth. Also defined is the look angle to observation point in the sky.
Using equations (11), (1) and (5) in reference [16], we can calculate the look angle to the satellite,
e, as a function of the Sun’s altitude, 𝑎𝑎.
𝑎𝑎(𝜀𝜀) = 𝜋𝜋
2 − 𝜀𝜀 − sin−1 � 𝑅𝑅𝐸𝐸
𝑅𝑅𝐸𝐸+ℎ sin �𝜋𝜋
2 − 𝜀𝜀�� + cos−1 � 𝑅𝑅𝐸𝐸
𝑅𝑅𝐸𝐸+ℎ�, (1)