Convert from equatorial coordinates to local horizontal coordinates, i.e. azimuth and altitude. The method is taken from equations 8.5 and 8.6 of reference 1, or, equivalently, from equations 12.5 and 12.6 of reference 2.
equatorialToLocalHorizontal(
rightAscension,
declination,
t,
longitude,
latitude
)A data frame containing columns altitude (angle above
horizon, in degrees) and azimuth (angle anticlockwise from south, in
degrees).
right ascension, e.g. calculated with
eclipticalToEquatorial().
declination, e.g. calculated with
eclipticalToEquatorial().
time of observation.
longitude of observation, positive in eastern hemisphere.
latitude of observation, positive in northern hemisphere.
Dan Kelley, based on formulae in references 1 and 2.
Meeus, Jean. Astronomical Formulas for Calculators. Second Edition. Richmond, Virginia, USA: Willmann-Bell, 1982.
Meeus, Jean. Astronomical Algorithms. Second Edition. Richmond, Virginia, USA: Willmann-Bell, 1991.
Other things related to astronomy:
angle2hms(),
eclipticalToEquatorial(),
julianCenturyAnomaly(),
julianDay(),
moonAngle(),
siderealTime(),
sunAngle(),
sunDeclinationRightAscension()