void eraNut06a(double date1, double date2, double *dpsi, double *deps)
/*
** - - - - - - - - - -
** e r a N u t 0 6 a
** - - - - - - - - - -
**
** IAU 2000A nutation with adjustments to match the IAU 2006
** precession.
**
** Given:
** date1,date2 double TT as a 2-part Julian Date (Note 1)
**
** Returned:
** dpsi,deps double nutation, luni-solar + planetary (Note 2)
**
** Notes:
**
** 1) The TT date date1+date2 is a Julian Date, apportioned in any
** convenient way between the two arguments. For example,
** JD(TT)=2450123.7 could be expressed in any of these ways,
** among others:
**
** date1 date2
**
** 2450123.7 0.0 (JD method)
** 2451545.0 -1421.3 (J2000 method)
** 2400000.5 50123.2 (MJD method)
** 2450123.5 0.2 (date & time method)
**
** The JD method is the most natural and convenient to use in
** cases where the loss of several decimal digits of resolution
** is acceptable. The J2000 method is best matched to the way
** the argument is handled internally and will deliver the
** optimum resolution. The MJD method and the date & time methods
** are both good compromises between resolution and convenience.
**
** 2) The nutation components in longitude and obliquity are in radians
** and with respect to the mean equinox and ecliptic of date,
** IAU 2006 precession model (Hilton et al. 2006, Capitaine et al.
** 2005).
**
** 3) The function first computes the IAU 2000A nutation, then applies
** adjustments for (i) the consequences of the change in obliquity
** from the IAU 1980 ecliptic to the IAU 2006 ecliptic and (ii) the
** secular variation in the Earth's dynamical form factor J2.
**
** 4) The present function provides classical nutation, complementing
** the IAU 2000 frame bias and IAU 2006 precession. It delivers a
** pole which is at current epochs accurate to a few tens of
** microarcseconds, apart from the free core nutation.
**
** Called:
** eraNut00a nutation, IAU 2000A
**
** References:
**
** Chapront, J., Chapront-Touze, M. & Francou, G. 2002,
** Astron.Astrophys. 387, 700
**
** Lieske, J.H., Lederle, T., Fricke, W. & Morando, B. 1977,
** Astron.Astrophys. 58, 1-16
**
** Mathews, P.M., Herring, T.A., Buffet, B.A. 2002, J.Geophys.Res.
** 107, B4. The MHB_2000 code itself was obtained on 9th September
** 2002 from ftp//maia.usno.navy.mil/conv2000/chapter5/IAU2000A.
**
** Simon, J.-L., Bretagnon, P., Chapront, J., Chapront-Touze, M.,
** Francou, G., Laskar, J. 1994, Astron.Astrophys. 282, 663-683
**
** Souchay, J., Loysel, B., Kinoshita, H., Folgueira, M. 1999,
** Astron.Astrophys.Supp.Ser. 135, 111
**
** Wallace, P.T., "Software for Implementing the IAU 2000
** Resolutions", in IERS Workshop 5.1 (2002)
**
** Copyright (C) 2013-2016, NumFOCUS Foundation.
** Derived, with permission, from the SOFA library. See notes at end of file.
*/
{
double t, fj2, dp, de;
/* Interval between fundamental date J2000.0 and given date (JC). */
t = ((date1 - ERFA_DJ00) + date2) / ERFA_DJC;
/* Factor correcting for secular variation of J2. */
fj2 = -2.7774e-6 * t;
/* Obtain IAU 2000A nutation. */
eraNut00a(date1, date2, &dp, &de);
/* Apply P03 adjustments (Wallace & Capitaine, 2006, Eqs.5). */
*dpsi = dp + dp * (0.4697e-6 + fj2);
*deps = de + de * fj2;
return;
}
void eraPn00a(double date1, double date2,
double *dpsi, double *deps, double *epsa,
double rb[3][3], double rp[3][3], double rbp[3][3],
double rn[3][3], double rbpn[3][3])
/*
** - - - - - - - - -
** e r a P n 0 0 a
** - - - - - - - - -
**
** Precession-nutation, IAU 2000A model: a multi-purpose function,
** supporting classical (equinox-based) use directly and CIO-based
** use indirectly.
**
** Given:
** date1,date2 double TT as a 2-part Julian Date (Note 1)
**
** Returned:
** dpsi,deps double nutation (Note 2)
** epsa double mean obliquity (Note 3)
** rb double[3][3] frame bias matrix (Note 4)
** rp double[3][3] precession matrix (Note 5)
** rbp double[3][3] bias-precession matrix (Note 6)
** rn double[3][3] nutation matrix (Note 7)
** rbpn double[3][3] GCRS-to-true matrix (Notes 8,9)
**
** Notes:
**
** 1) The TT date date1+date2 is a Julian Date, apportioned in any
** convenient way between the two arguments. For example,
** JD(TT)=2450123.7 could be expressed in any of these ways,
** among others:
**
** date1 date2
**
** 2450123.7 0.0 (JD method)
** 2451545.0 -1421.3 (J2000 method)
** 2400000.5 50123.2 (MJD method)
** 2450123.5 0.2 (date & time method)
**
** The JD method is the most natural and convenient to use in
** cases where the loss of several decimal digits of resolution
** is acceptable. The J2000 method is best matched to the way
** the argument is handled internally and will deliver the
** optimum resolution. The MJD method and the date & time methods
** are both good compromises between resolution and convenience.
**
** 2) The nutation components (luni-solar + planetary, IAU 2000A) in
** longitude and obliquity are in radians and with respect to the
** equinox and ecliptic of date. Free core nutation is omitted;
** for the utmost accuracy, use the eraPn00 function, where the
** nutation components are caller-specified. For faster but
** slightly less accurate results, use the eraPn00b function.
**
** 3) The mean obliquity is consistent with the IAU 2000 precession.
**
** 4) The matrix rb transforms vectors from GCRS to J2000.0 mean
** equator and equinox by applying frame bias.
**
** 5) The matrix rp transforms vectors from J2000.0 mean equator and
** equinox to mean equator and equinox of date by applying
** precession.
**
** 6) The matrix rbp transforms vectors from GCRS to mean equator and
** equinox of date by applying frame bias then precession. It is
** the product rp x rb.
**
** 7) The matrix rn transforms vectors from mean equator and equinox
** of date to true equator and equinox of date by applying the
** nutation (luni-solar + planetary).
**
** 8) The matrix rbpn transforms vectors from GCRS to true equator and
** equinox of date. It is the product rn x rbp, applying frame
** bias, precession and nutation in that order.
**
** 9) The X,Y,Z coordinates of the IAU 2000A Celestial Intermediate
** Pole are elements (3,1-3) of the GCRS-to-true matrix,
** i.e. rbpn[2][0-2].
**
** 10) It is permissible to re-use the same array in the returned
** arguments. The arrays are filled in the order given.
**
** Called:
** eraNut00a nutation, IAU 2000A
** eraPn00 bias/precession/nutation results, IAU 2000
**
** Reference:
**
** Capitaine, N., Chapront, J., Lambert, S. and Wallace, P.,
** "Expressions for the Celestial Intermediate Pole and Celestial
** Ephemeris Origin consistent with the IAU 2000A precession-
** nutation model", Astron.Astrophys. 400, 1145-1154 (2003)
**
** n.b. The celestial ephemeris origin (CEO) was renamed "celestial
** intermediate origin" (CIO) by IAU 2006 Resolution 2.
**
** Copyright (C) 2013-2015, NumFOCUS Foundation.
** Derived, with permission, from the SOFA library. See notes at end of file.
*/
{
/* Nutation. */
eraNut00a(date1, date2, dpsi, deps);
/* Remaining results. */
eraPn00(date1, date2, *dpsi, *deps, epsa, rb, rp, rbp, rn, rbpn);
return;
}
