diff options
Diffstat (limited to 'ext/date/lib/astro.h')
| -rw-r--r-- | ext/date/lib/astro.h | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/ext/date/lib/astro.h b/ext/date/lib/astro.h new file mode 100644 index 0000000..7b85c76 --- /dev/null +++ b/ext/date/lib/astro.h @@ -0,0 +1,51 @@ +/* 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 ) + |