$LastChangedDate: 27-Juil-2011 $

# CL_mod_meanObliquity

Mean obliquity (IERS 1996)

## Calling Sequence

       [eps0[,eps0p[,eps0pp]]]=CL_mod_meanObliquity(jj_tai,sec_tai[,flag])

## Description

- Computes the mean obliquity and its time derivatives (see IERS standards 1996).

## Parameters

jj_tai :

  (integer) Modified (1950.0) Julian day (1xN)

sec_tai :

  Seconds (TAI time scale) (1xN)

flag :

  (string, optional) "p" -> eps0 and eps0p; "s" -> eps0, eps0p and eps0pp (default depends on number of outputs)

eps0 :

  Mean obliquity [rad] (1xN)

eps0p :

  (optional) First time derivative of [rad/s] (1xN)

eps0pp :

  (optional) Second time derivative of eps0 [rad/s^2] (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_precessionAngles

## Examples

    jj_tai = [19500:1:20500];
    ss_tai = 43200*ones(jj_tai);
    [eps0,eps0p,eps0pp]=CL_mod_meanObliquity(jj_tai,ss_tai,"s");
    plot(jj_tai'+ss_tai'/86400,eps0'*180/%pi);