src/Marando/IAU/iauGmst06.php
public static function Gmst06($uta, $utb, $tta, $ttb) {
    $t;
    $gmst;

    /* TT Julian centuries since J2000.0. */
    $t = (($tta - DJ00) + $ttb) / DJC;

    /* Greenwich mean sidereal time, IAU 2006. */
    $gmst = IAU::Anp(IAU::Era00($uta, $utb) +
                    ( 0.014506 +
                    ( 4612.156534 +
                    ( 1.3915817 +
                    ( -0.00000044 +
                    ( -0.000029956 +
                    ( -0.0000000368 ) * $t) * $t) * $t) * $t) * $t) * DAS2R);

    return $gmst;
  }
public static function Gmst06($uta, $utb, $tta, $ttb) {
    $t;
    $gmst;

    /* TT Julian centuries since J2000.0. */
    $t = (($tta - DJ00) + $ttb) / DJC;

    /* Greenwich mean sidereal time, IAU 2006. */
    $gmst = IAU::Anp(IAU::Era00($uta, $utb) +
                    ( 0.014506 +
                    ( 4612.156534 +
                    ( 1.3915817 +
                    ( -0.00000044 +
                    ( -0.000029956 +
                    ( -0.0000000368 ) * $t) * $t) * $t) * $t) * $t) * DAS2R);

    return $gmst;
  }
public static function Gmst06 ( $ uta , $ utb , $ tta , $ ttb ) { $ t ; $ gmst ; /* TT Julian centuries since J2000.0. */ $ t = ( ( $ tta - DJ00 ) + $ ttb ) / DJC ; /* Greenwich mean sidereal time, IAU 2006. */ $ gmst = IAU :: Anp ( IAU :: Era00 ( $ uta , $ utb ) + ( 0.014506 + ( 4612.156534 + ( 1.3915817 + ( - 0.00000044 + ( - 0.000029956 + ( - 0.0000000368 ) * $ t ) * $ t ) * $ t ) * $ t ) * $ t ) * DAS2R ) ; return $ gmst ; }
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i a u G m s t 0 6
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Greenwich mean sidereal time (consistent with IAU 2006 precession).

This function is part of the International Astronomical Union's
SOFA (Standards Of Fundamental Astronomy) software collection.

Status:  canonical model.

Given:
uta,utb    double    UT1 as a 2-part Julian Date (Notes 1,2)
tta,ttb    double    TT as a 2-part Julian Date (Notes 1,2)

Returned (function value):
double    Greenwich mean sidereal time (radians)

Notes:

1) The UT1 and TT dates uta+utb and tta+ttb respectively, are both
Julian Dates, apportioned in any convenient way between the
argument pairs.  For example, JD=2450123.7 could be expressed in
any of these ways, among others:

Part A        Part B

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 (in the case of UT;  the TT is not at all critical
in this respect).  The J2000 and MJD methods are good compromises
between resolution and convenience.  For UT, the date & time
method is best matched to the algorithm that is used by the Earth
rotation angle function, called internally:  maximum precision is
delivered when the uta argument is for 0hrs UT1 on the day in
question and the utb argument lies in the range 0 to 1, or vice
versa.

2) Both UT1 and TT are required, UT1 to predict the Earth rotation
and TT to predict the effects of precession.  If UT1 is used for
both purposes, errors of order 100 microarcseconds result.

3) This GMST is compatible with the IAU 2006 precession and must not
be used with other precession models.

4) The result is returned in the range 0 to 2pi.

Called:
iauEra00     Earth rotation angle, IAU 2000
iauAnp       normalize angle into range 0 to 2pi

Reference:

Capitaine, N., Wallace, P.T. & Chapront, J., 2005,
Astron.Astrophys. 432, 355

This revision:  2013 June 18

SOFA release 2015-02-09

Copyright (C) 2015 IAU SOFA Board.  See notes at end.
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