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equation_of_time.info
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equation_of_time.info
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This is equation_of_time.info, produced by makeinfo version 6.0 from
equation_of_time.texi.
File: equation_of_time.info, Node: Top, Next: Introduction to equation_of_time, Prev: (dir), Up: (dir)
equation_of_time
****************
* Menu:
* Introduction to equation_of_time::
* Definitions for equation_of_time::
* Function and variable index::
1 equation_of_time
******************
File: equation_of_time.info, Node: Introduction to equation_of_time, Next: Definitions for equation_of_time, Prev: Top, Up: Top
1.1 Introduction to equation_of_time
====================================
'equation_of_time' returns the difference between the standard mean day
and the actual. This is the difference in minutes between the Sun's
standard meridian and the actual transit. For example, a standard clock
will indicate the passage from AM to PM at noon, while the actual maybe
at 12:45 pm. This difference, 45 minutes, is the equation of time.
There are two main causes - first is that the Earth's orbital speed
varies throughout the year, and second that the Earth rotational axis is
inclined to the orbital plane. The equation of time can also be used to
display the observed position of the Sun in the sky during the day with
respect to seasonal variation.
File: equation_of_time.info, Node: Definitions for equation_of_time, Next: Function and variable index, Prev: Introduction to equation_of_time, Up: Top
1.2 Definitions for equation_of_time
====================================
-- Function: equation_of_time_full(<T>, <UT>)
Returns declination <dec>, equation of time <E> and ecliptic
longitude <lambda>.
-- Function: equation_of_time(<T>, <UT>)
Returns declination <dec> and equation of time <E>.
-- Function: analemma(<day>,<month>,<year>,<tzi>,<ds>)
Returns declination <dec> and equation of time <E>.
-- Function: greenwich_hour_angle(<UT>, <E>)
Returns the Greenwich hour angle (degrees).
-- Function: sun_hour_angle(<phi>, <h>, <dec>)
Returns the sun hour angle (degrees).
-- Function: calculate_rise_time(<T>, <lat>, <lon>, <sgn>, <h>)
Returns sunrise (if <sgn> = +1) or sunset (if <sgn> = -1) universal
times in hours.
-- Function: julian_dow(<dow>,<week>,<month>,<year>)
Returns the Julian day of nth <dow>. For example, for year 2016,
1st Sunday in November julian_dow(1,1,11,2016) and 2nd Sunday of
March julian_dow(1,2,3,2016).
-- Function: day_of_year(<day>,<month>,<year>)
Returns the day number of the year.
-- Function: DST(<jd>,<ds>)
Returns standard Daylight savings correction.
-- Function: UT_to_local_time(<UT>,<jd>,<tz>,<ds>)
Returns local time given universal time.
-- Function: local_to_UT_time(<LT>,<jd>,<tz>,<ds>)
Returns universal time given local time.
-- Function: day_duration(<T>, <jd>, <lat>, <lon>, <h>)
Returns the length of the day, from sunrise to sunset.
-- Function: observer_coord(<hour_angle>, <dec>, <lat>)
Returns the observed azimuth and altitude given <hour_angle>, <dec>
at observer latitude <lat>
-- Function: observer_coord_gha(<gha>, <dec>, <lat>, <lon>)
Returns the observed azimuth and altitude given <gha>, <dec> at
observer latitude <lat> longitude <lon>
-- Function: sun_alt_az(<jd>,<tz>,<ds>,<lat>, <lon>, <h>)
Returns lists of azimuth and altitude, and labels.
-- Variable: day
Day of month.
-- Variable: dec
declination in degrees.
-- Variable: dow
Day of week.
-- Variable: ds
Daylight savings offset in hour.
-- Variable: E
Equation of time in minutes.
-- Variable: gha
Greenwich hour angle in degrees.
-- Variable: h
Observer altitude above ground level in meters.
-- Variable: hour_angle
Hour angle in degrees.
-- Variable: jd
Julian day number.
-- Variable: lambda
Ecliptic longitude in degrees.
-- Variable: lat
Observer latitude in degrees.
-- Variable: lon
Observer longitude in degrees.
-- Variable: LT
Local time, e.g. time in Observer frame.
-- Variable: month
Month of year.
-- Variable: phi
Observer latitude in degrees.
-- Variable: sgn
Setting. +1 for rise. -1 for set.
-- Variable: T
Julian days in centuries from J2000.
-- Variable: tz
Timezone offset in hours.
-- Variable: tzi
Timeone offset in hours
-- Variable: UT
Universal time in hours.
-- Variable: week
Week of month.
-- Variable: year
Conventional year number.
File: equation_of_time.info, Node: Function and variable index, Prev: Definitions for equation_of_time, Up: Top
Appendix A Function and variable index
**************************************
[index ]
* Menu:
* analemma(<day>,<month>,<year>,<tzi>,<ds>): Definitions for equation_of_time.
(line 11)
* calculate_rise_time(<T>,: Definitions for equation_of_time.
(line 17)
* day_duration(<T>,: Definitions for equation_of_time.
(line 32)
* day_of_year(<day>,<month>,<year>): Definitions for equation_of_time.
(line 24)
* DST(<jd>,<ds>): Definitions for equation_of_time.
(line 26)
* equation_of_time(<T>,: Definitions for equation_of_time.
(line 9)
* equation_of_time_full(<T>,: Definitions for equation_of_time.
(line 6)
* greenwich_hour_angle(<UT>,: Definitions for equation_of_time.
(line 13)
* julian_dow(<dow>,<week>,<month>,<year>): Definitions for equation_of_time.
(line 20)
* local_to_UT_time(<LT>,<jd>,<tz>,<ds>): Definitions for equation_of_time.
(line 30)
* observer_coord(<hour_angle>,: Definitions for equation_of_time.
(line 34)
* observer_coord_gha(<gha>,: Definitions for equation_of_time.
(line 37)
* sun_alt_az(<jd>,<tz>,<ds>,<lat>,: Definitions for equation_of_time.
(line 40)
* sun_hour_angle(<phi>,: Definitions for equation_of_time.
(line 15)
* UT_to_local_time(<UT>,<jd>,<tz>,<ds>): Definitions for equation_of_time.
(line 28)
[index ]
* Menu:
* day: Definitions for equation_of_time.
(line 43)
* dec: Definitions for equation_of_time.
(line 45)
* dow: Definitions for equation_of_time.
(line 47)
* ds: Definitions for equation_of_time.
(line 49)
* E: Definitions for equation_of_time.
(line 51)
* gha: Definitions for equation_of_time.
(line 53)
* h: Definitions for equation_of_time.
(line 55)
* hour_angle: Definitions for equation_of_time.
(line 57)
* jd: Definitions for equation_of_time.
(line 59)
* lambda: Definitions for equation_of_time.
(line 61)
* lat: Definitions for equation_of_time.
(line 63)
* lon: Definitions for equation_of_time.
(line 65)
* LT: Definitions for equation_of_time.
(line 67)
* month: Definitions for equation_of_time.
(line 69)
* phi: Definitions for equation_of_time.
(line 71)
* sgn: Definitions for equation_of_time.
(line 73)
* T: Definitions for equation_of_time.
(line 75)
* tz: Definitions for equation_of_time.
(line 77)
* tzi: Definitions for equation_of_time.
(line 79)
* UT: Definitions for equation_of_time.
(line 81)
* week: Definitions for equation_of_time.
(line 83)
* year: Definitions for equation_of_time.
(line 85)
Tag Table:
Node: Top93
Node: Introduction to equation_of_time393
Node: Definitions for equation_of_time1275
Node: Function and variable index4483
End Tag Table