Name

CL_mod_equinoxesEquation — Equation of the equinoxes (IERS 1996)

Calling Sequence

   [equi[,equip]]=CL_mod_equinoxesEquation(dPsi,eps0,F5[,dPsip,epsOp,F5p])
   
   

Description

  • Calculate equation of the equinoxes - standard IERS 1996 (Greenwich sideral time - Mean Greenwich sideral time)
  • Last update : 27/03/2007

Parameters

dPsi:

longitude (see CL_mod_nutationAngles) [rad](1xN)

dPsip:

(optional with eps0p and F5p) longitude first time derivative (see CL_mod_nutationAngles) [rad/s] (1xN)

eps0:

mean obliquity (see CL_mod_meanObliquity) [rad] (1xN)

epsOp:

(optional with dPsip and F5p) mean obliquity first time derivative (see CL_mod_meanObliquity) [rad/s] (1xN)

F5:

Mean longitude of Moon's ascending node (see CL_mod_nutationArg) [rad] (1xN)

F5p:

(optional with eps0p and dPsip) Mean longitude of Moon's ascending node first time derivative (see CL_mod_nutationArg) [rad/s] (1xN)

equi:

equinoxes equation (1xN)

equip:

(optional, needs dPsip, eps0p and F5p) first time derivative of equi (1xN)

Authors

CNES - DCT/SB

Bibliography

1 IERS Conventions (1996), Dennis D. McCarthy

2 Explanatory Supplement to the Astronomical Almanac, Seidelman (1992)

See also

CL_mod_nutationAngles, CL_mod_nutationArg, CL_mod_meanObliquity

Examples

jj_tai = [19500:1:20500];
ss_tai = 43200*ones(jj_tai);
[NUT,F,NUTP,FP,NUTPP,FPP]=CL_mod_nutationAngles(jj_tai,ss_tai,"s");  //calculation of nutation angles (dPsi,dEps)
[eps0,eps0p,eps0pp]=CL_mod_meanObliquity(jj_tai,ss_tai,"s");  //calculation of mean obliquity
[equi,equip]=CL_mod_equinoxesEquation(NUT(1,:),eps0,F(5,:),NUTP(1,:),eps0p,FP(5,:)); //equinoxes equation
plot(jj_tai'+ss_tai'/86400,equi');