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/* This macro computes the length of the day, from sunrise to sunset. */
/* Sunrise/set is considered to occur when the Sun's upper limb is */
/* 35 arc minutes below the horizon (this accounts for the refraction */
/* of the Earth's atmosphere). */
#define day_length(year,month,day,lon,lat) \
__daylen__( year, month, day, lon, lat, -35.0/60.0, 1 )
/* This macro computes the length of the day, including civil twilight. */
/* Civil twilight starts/ends when the Sun's center is 6 degrees below */
/* the horizon. */
#define day_civil_twilight_length(year,month,day,lon,lat) \
__daylen__( year, month, day, lon, lat, -6.0, 0 )
/* This macro computes the length of the day, incl. nautical twilight. */
/* Nautical twilight starts/ends when the Sun's center is 12 degrees */
/* below the horizon. */
#define day_nautical_twilight_length(year,month,day,lon,lat) \
__daylen__( year, month, day, lon, lat, -12.0, 0 )
/* This macro computes the length of the day, incl. astronomical twilight. */
/* Astronomical twilight starts/ends when the Sun's center is 18 degrees */
/* below the horizon. */
#define day_astronomical_twilight_length(year,month,day,lon,lat) \
__daylen__( year, month, day, lon, lat, -18.0, 0 )
/* This macro computes times for sunrise/sunset. */
/* Sunrise/set is considered to occur when the Sun's upper limb is */
/* 35 arc minutes below the horizon (this accounts for the refraction */
/* of the Earth's atmosphere). */
#define timelib_astro_sun_rise_set(ts,lon,lat,hrise,hset,rise,set) \
timelib_astro_rise_set_altitude( ts, lon, lat, -35.0/60.0, 1, hrise, hset, rise, set )
/* This macro computes the start and end times of civil twilight. */
/* Civil twilight starts/ends when the Sun's center is 6 degrees below */
/* the horizon. */
#define civil_twilight(ts,lon,lat,start,end) \
timelib_astro_rise_set_altitude( ts, lon, lat, -6.0, 0, start, end )
/* This macro computes the start and end times of nautical twilight. */
/* Nautical twilight starts/ends when the Sun's center is 12 degrees */
/* below the horizon. */
#define nautical_twilight(ts,lon,lat,start,end) \
timelib_astro_rise_set_altitude( ts, lon, lat, -12.0, 0, start, end )
/* This macro computes the start and end times of astronomical twilight. */
/* Astronomical twilight starts/ends when the Sun's center is 18 degrees */
/* below the horizon. */
#define astronomical_twilight(ts,lon,lat,start,end) \
timelib_astro_rise_set_altitude( ts, lon, lat, -18.0, 0, start, end )