Convert Equatorial Coordinate to Local Horizontal Coordinate

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.

Usage

equatorialToLocalHorizontal(
  rightAscension,
  declination,
  t,
  longitude,
  latitude
)

Arguments

rightAscension

right ascension, e.g. calculated with eclipticalToEquatorial().

declination

declination, e.g. calculated with eclipticalToEquatorial().

t

time of observation.

longitude

longitude of observation, positive in eastern hemisphere.

latitude

latitude of observation, positive in northern hemisphere.

Value

A data frame containing columns altitude (angle above horizon, in degrees) and azimuth (angle anticlockwise from south, in degrees).

References

• 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.

See also

Other things related to astronomy: angle2hms(), eclipticalToEquatorial(), julianCenturyAnomaly(), julianDay(), moonAngle(), siderealTime(), sunAngle(), sunDeclinationRightAscension()

Author

Dan Kelley, based on formulae in references 1 and 2.