astro: Calculations for position of the sun and moon

In Trackage/tripEstimation: Metropolis Sampler and Supporting Functions for Estimating Animal Movement from Archival Tags and Satellite Fixes

Calculations for position of the sun and moon

Description

This set of functions provides simple position calculations for the sun and moon, taken from Pascal routines published in Montenbruck and Pfleger (1994, Dunlop).

These are completely independent from the (specifically optimized) solar elevation calculations available via [elevation and solar].

Usage

astro(lon, lat, astro.calc)

EQUHOR(DEC, TAU, PHI)

FRAC(x)

LMST(MJDay, LAMBDA)

lunar(time)

mini.sun(time)

MJD(date)

POLAR(X, Y, Z)

Arguments

lon	vector of longitudes
lat	vector of latitudes
astro.calc	list object containing RA right ascension

DEC	declination
TAU	TAU
PHI	PHI

x

number

MJDay	modified julian day
LAMBDA	LAMBDA

time	vector of date-times in POSIXct format

date	vector of date-times in POSIXct format

X	x-coordinate
Y	y-coordinate
Z	z-coordinate

Value

astro returns a list object with the components of the moon or sun's position,

r	rho component
theta	theta component - elevation
phi	phi component - azimuth

Warning

Some of this could be faster (particularly the use of LMST in "astro" is not precalculated)

Note

Thanks to [e-mail] for pointing out a mistake pre-0.0-27

Author(s)

Michael D. Sumner

References

@BOOK{,
  title = {Astronomy on the Personal Computer},
  publisher = {Springer-Verlag, Berlin},
  year = {1994},
  author = {Oliver Montenbruck and Thomas Pfleger},
  edition = {2  (translated from German by Storm Dunlop)},
}

See Also

See Also elevation

Examples

## the moon
tm <- Sys.time() + seq(by = 3600, length = 100)
moon <- lunar(tm)
rtp <- astro(147, -42, moon)
op <- par(mfrow = c(2,1))
plot(tm, rtp$theta, main = "lunar elevation, Hobart")
plot(tm, rtp$phi, main = "lunar azimuth, Hobart")
par(op)

## the sun
tm <- Sys.time() + seq(by = 3600, length = 100)
sun <- mini.sun(tm)
rtp <- astro(147, -42, sun)
op <- par(mfrow = c(2,1))
plot(tm, rtp$theta, main = "solar elevation, Hobart")
plot(tm, rtp$phi, main = "solar azimuth, Hobart")
par(op)
  elev.gmt <- mkElevationSeg(1, tm)
  plot(tm, rtp$theta, main = "solar elevation mini.sun versus NOAA")
  lines(tm, elev.gmt(1, 147, -42))

Trackage/tripEstimation documentation built on April 24, 2023, 6:57 p.m.