body.position {skyscapeR}

Computes position of Solar System bodies in equatorial coordinates

Description

This function calculates the geocentric or topocentric declination and right ascension of solar system bodies at a given time. It is a wrapper for function swe_calc_ut of package swephR.

Usage

body.position(
  obj = "sun",
  time,
  timezone,
  calendar,
  dec,
  loc = NULL,
  refraction,
  atm,
  temp,
  verbose = T
)

Arguments

obj

(Optional) String containing name of the solar system body of interest. Can be any of the planets (inc. Pluto), the Moon, the Sun or the Ecliptic. Defaults to 'sun'.

time

Either a string containing the date and time in the format "YYYY/MM/DD HH:MM:SS" (see timestring), or a numeric containing the julian date (see time2jd).

timezone

(Optional) Timezone of input either as a known acronym (e.g. "GMT", "CET") or a string with continent followed by country capital (e.g. "Europe/London"). See timezones for details. Only needed if time is a string. #' If not given the value set by skyscapeR.vars will be used instead.

calendar

(Optional) Calendar used in parameter time. G for gregorian and J for julian. Only needed if time is a string. If not given the value set by skyscapeR.vars will be used instead.

dec

(Optional) Output declination: geo for the geocentric, or topo for the topocentric frame of reference. If not given the value set by skyscapeR.vars will be used instead.

loc

(Optional) Location, only needed if output is in topocentric declination.

refraction

(Optional) Whether atmospheric refraction is to be taken into account. If not given the value set by skyscapeR.vars will be used instead.

atm

(Optional) Atmospheric pressure for refraction calculation. If not given the value set by skyscapeR.vars will be used instead.

temp

(Optional) Atmospheric temperature for refraction calculation. If not given the value set by skyscapeR.vars will be used instead.

verbose

(Optional) Boolean to control whether or not to display text. Default is TRUE.

See Also

swe_calc_ut, timestring, time2jd

Examples

# Position of the sun at noon GMT on Christmas day 2018:
body.position('sun', '2018/12/25 12:00:00', timezone='GMT')

# Declination of the moon at same time
body.position('moon', '2018/12/25 12:00:00', timezone='GMT')$equatorial$Dec