Procedures for the Moon. More...

Functions/Subroutines
subroutine	elp82b_lbr (tjj, ll, bb, rr)
	Calculate the apparent geocentric ecliptical position of the Moon, using the Lunar Solution ELP 2000-82B.

subroutine	elp_mpp02_lbr (jd, mode, lon, lat, rad, precess)
	Compute the spherical lunar coordinates using the ELP2000/MPP02 lunar theory in the dynamical mean ecliptic and equinox of J2000.

subroutine	elp_mpp02_xyz (jd, mode, xyz, vxyz, ierr)
	Compute the rectangular lunar coordinates using the ELP/MPP02 lunar theory in the dynamical mean ecliptic and equinox of J2000.

subroutine	moonpos_la (jd, calc, nt)
	Quick, lower-accuracy lunar coordinates; ~600x faster than ELP.

real(double) function	moonmagn (pa, delta)
	Calculate the magnitude of the Moon.

Detailed Description

Procedures for the Moon.

Function/Subroutine Documentation

◆ elp82b_lbr()

subroutine thesky_moon::elp82b_lbr	(	real(double), intent(in)	tjj,
		real(double), intent(out)	ll,
		real(double), intent(out)	bb,
		real(double), intent(out)	rr )

Calculate the apparent geocentric ecliptical position of the Moon, using the Lunar Solution ELP 2000-82B.

Parameters

tjj	Time for calculation in Julian millenia after 2000.0
ll	Apparent geocentric ecliptical longitude (output)
bb	Apparent geocentric ecliptical latitude (output)
rr	Apparent geocentric distance (output)

Note

This is supposed to be the ELP2000-85 version, with the corrections from the 1998 paper (mean arguments up to t^4, etc,). However, the accuracy seems to be less than promised for historical calculations (0.1° rather than 0.01° for CE 0). The subroutine elp_mpp02_lbr() below is supposed to give better results (but then again, so is this one).
Differences compared to ELP-MPP02 (ELP82b minus ELP-MPP02):
- longitude: +0.00001° in CE 1975, ~+0.11° in CE 0/4000 and ~+0.65° in 3000 BCE (systematically drifting to positive values)
  - replacing w(1,2) = -5.8883 with -6.8084 removes the systematic drift to +0.65° @3000 BCE; (see data.f90 / readmoondata()) the drift now oscillates around +-0.012°;
- latitude: ~0.00000° in CE 1990, ~+/-0.01° in CE 0/4000 and +/- ~0.06° (now ~0.006°) in 3000 BCE
- distance: +/-0.03 km in CE 2000, +/- ~30 km in CE 0/4000 and +/- ~300 km (now ~20km) in 3000 BCE

See also

Chapront-Touzé & Chapront, A&A, 124, 50 (1983)
Chapront-Touzé & Chapront, A&A, 190, 342 (1988)
ftp://cdsarc.u-strasbg.fr/pub/cats/VI/79/

Definition at line 55 of file moon_position.f90.

References thesky_moondata::a0, thesky_moondata::ath, thesky_moondata::nrang, thesky_moondata::nterm, thesky_moondata::pc1, thesky_moondata::pc2, thesky_moondata::pc3, thesky_moondata::per1, thesky_moondata::per2, thesky_moondata::per3, thesky_moondata::t, and thesky_moondata::w.

Referenced by thesky_planets::planet_position().

◆ elp_mpp02_lbr()

subroutine thesky_moon::elp_mpp02_lbr	(	real(double), intent(in)	jd,
		integer, intent(in)	mode,
		real(double), intent(out)	lon,
		real(double), intent(out)	lat,
		real(double), intent(out)	rad,
		logical, intent(in), optional	precess )

Compute the spherical lunar coordinates using the ELP2000/MPP02 lunar theory in the dynamical mean ecliptic and equinox of J2000.

Parameters

jd	Julian day to compute Moon position for
mode	Index of the corrections to the constants: 0-Fit to LLR observations, 1-Fit to DE405 1950-2060 (historical)
lon	Ecliptic longitude (rad) (output)
lat	Ecliptic latitude (rad) (output)
rad	Distance (AU) (output)
precess	Apply precession (input, optional, default=.true.)

Note: See Lunar Solution ELP 2000/MPP02, Chapront & Francou (2002): ftp://cyrano-se.obspm.fr/pub/2_lunar_solutions/2_elpmpp02/

Definition at line 188 of file moon_position.f90.

References elp_mpp02_xyz(), and thesky_coordinates::precess_ecl().

Referenced by thesky_planets::planet_position().

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◆ elp_mpp02_xyz()

subroutine thesky_moon::elp_mpp02_xyz	(	real(double), intent(in)	jd,
		integer, intent(in)	mode,
		real(double), dimension(3), intent(out)	xyz,
		real(double), dimension(3), intent(out)	vxyz,
		integer, intent(out)	ierr )

Compute the rectangular lunar coordinates using the ELP/MPP02 lunar theory in the dynamical mean ecliptic and equinox of J2000.

Parameters

jd	Julian day to compute Moon position for
mode	Index of the corrections to the constants: 0-Fit to LLR observations, 1-Fit to DE405 1950-2060 (historical)
xyz	Geocentric rectangular coordinates: (output) xyz(1) : Position X (km) xyz(2) : Position Y (km) xyz(3) : Position Z (km)
vxyz	Geocentric rectangular velocities: (output) vxyz(1) : Velocity X' (km/day) vxyz(2) : Velocity Y' (km/day) vxyz(3) : Velocity Z' (km/day)
ierr	File error index - ierr=0: no error, ierr=1: file error (output)

Note

The subroutine elp_mpp02() uses two modules:
- elp_mpp02_constants: Constants of the solution ELP/MPP02 (input),
- elp_mpp02_series: Series of the solution ELP/MPP02 (input).
The nominal values of some constants have to be corrected. There are two sets of corrections, which can be selected using the parameter 'mode' (used in elp_mpp02_initialise()).
- mode=0, the constants are fitted to LLR observations provided from 1970 to 2001; it is the default value;
- mode=1, the constants are fitted to DE405 ephemeris over one century (1950-2060); the lunar angles W1, W2, W3 receive also additive corrections to the secular coefficients ('historical mode'). When the mode is changed, the constants will be reinitialised and the data file reread.
Solutions (discussed) in the paper:
- ELP (original):
  - ELP2000-82: using VSOP82 (1983)
  - ELP2000-85: new mean lunar arguments, higher truncation level, longer time range (1988)
  - ELP2000-82B, here called "ELP": ELP2000-82, using mean lunar arguments from ELP2000-85 (19??)
- ELP/MPP01: using latest planetary perturbations from MPP01 and VSOP2000, but simpler than MPP01
- ELP/MPP02: ELP/MPP01, but for some arguments back to ELP + different selection of perturbations + lower truncation. Good fit with DE 405 in [1950,2060]
- ELP/MPP02*: improved secular arguments, better long-term comparison to DE 405/406 [-3000,2500]
- ELP/MPP02(LLR): ELP/MPP02(?), optimised for lunar ranging since 1970
- ELPa: ELP + few Poisson terms (tested in the current study only?)
- ELPa: ELPa + better secular arguments (as in ELP/MPP02*)
It is not entirely clear which version is given below, but we can hope it is ELP/MPP02*. However, the subroutine elp82b_lbr() above is known to underperform (by a factor of 10) in accuracy.