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erfasrc/src/erfam.h  view on Meta::CPAN

/*
**  - - - - - - - -
**   e r f a m . h
**  - - - - - - - -
**
**  Macros used by ERFA library.
**
**  Copyright (C) 2013-2020, NumFOCUS Foundation.
**  Derived, with permission, from the SOFA library.  See notes at end of file.
*/

/* Star-independent astrometry parameters */
typedef struct {
   double pmt;        /* PM time interval (SSB, Julian years) */
   double eb[3];      /* SSB to observer (vector, au) */
   double eh[3];      /* Sun to observer (unit vector) */
   double em;         /* distance from Sun to observer (au) */
   double v[3];       /* barycentric observer velocity (vector, c) */
   double bm1;        /* sqrt(1-|v|^2): reciprocal of Lorenz factor */
   double bpn[3][3];  /* bias-precession-nutation matrix */
   double along;      /* longitude + s' + dERA(DUT) (radians) */
   double phi;        /* geodetic latitude (radians) */
   double xpl;        /* polar motion xp wrt local meridian (radians) */
   double ypl;        /* polar motion yp wrt local meridian (radians) */
   double sphi;       /* sine of geodetic latitude */
   double cphi;       /* cosine of geodetic latitude */
   double diurab;     /* magnitude of diurnal aberration vector */
   double eral;       /* "local" Earth rotation angle (radians) */
   double refa;       /* refraction constant A (radians) */
   double refb;       /* refraction constant B (radians) */
} eraASTROM;
/* (Vectors eb, eh, em and v are all with respect to BCRS axes.) */

/* Body parameters for light deflection */
typedef struct {
   double bm;         /* mass of the body (solar masses) */
   double dl;         /* deflection limiter (radians^2/2) */
   double pv[2][3];   /* barycentric PV of the body (au, au/day) */
} eraLDBODY;

/* Leap second definition */
typedef struct {
   int iyear, month;
   double delat;
} eraLEAPSECOND;

/* Pi */
#define ERFA_DPI (3.141592653589793238462643)

/* 2Pi */
#define ERFA_D2PI (6.283185307179586476925287)

/* Radians to degrees */
#define ERFA_DR2D (57.29577951308232087679815)

/* Degrees to radians */
#define ERFA_DD2R (1.745329251994329576923691e-2)

/* Radians to arcseconds */
#define ERFA_DR2AS (206264.8062470963551564734)

/* Arcseconds to radians */
#define ERFA_DAS2R (4.848136811095359935899141e-6)

/* Seconds of time to radians */
#define ERFA_DS2R (7.272205216643039903848712e-5)

/* Arcseconds in a full circle */
#define ERFA_TURNAS (1296000.0)

/* Milliarcseconds to radians */
#define ERFA_DMAS2R (ERFA_DAS2R / 1e3)

/* Length of tropical year B1900 (days) */
#define ERFA_DTY (365.242198781)

/* Seconds per day. */
#define ERFA_DAYSEC (86400.0)

/* Days per Julian year */
#define ERFA_DJY (365.25)

/* Days per Julian century */
#define ERFA_DJC (36525.0)

/* Days per Julian millennium */
#define ERFA_DJM (365250.0)

/* Reference epoch (J2000.0), Julian Date */
#define ERFA_DJ00 (2451545.0)

/* Julian Date of Modified Julian Date zero */
#define ERFA_DJM0 (2400000.5)

/* Reference epoch (J2000.0), Modified Julian Date */
#define ERFA_DJM00 (51544.5)

/* 1977 Jan 1.0 as MJD */
#define ERFA_DJM77 (43144.0)

/* TT minus TAI (s) */
#define ERFA_TTMTAI (32.184)

/* Astronomical unit (m, IAU 2012) */
#define ERFA_DAU (149597870.7e3)

/* Speed of light (m/s) */
#define ERFA_CMPS 299792458.0

/* Light time for 1 au (s) */
#define ERFA_AULT (ERFA_DAU/ERFA_CMPS)

/* Speed of light (au per day) */
#define ERFA_DC (ERFA_DAYSEC/ERFA_AULT)

/* L_G = 1 - d(TT)/d(TCG) */
#define ERFA_ELG (6.969290134e-10)

/* L_B = 1 - d(TDB)/d(TCB), and TDB (s) at TAI 1977/1/1.0 */
#define ERFA_ELB (1.550519768e-8)