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G.2.2.5 Sun data %[format]?argument special texts

%[format]o[*][mode]ISO-6709:1983-co-ordinate[,[+|-]mmmm|hh:[mm]] references the approximate time of sunrise by default,
%[format]s[*][mode]ISO-6709:1983-co-ordinate[,[+|-]mmmm|hh:[mm]] references the approximate time of sunset by default,
%[format]u[*][mode]ISO-6709:1983-co-ordinate[,[+|-]mmmm|hh:[mm]] references the approximate period of visibility of the Sun (solar day length) by default,
%[format]z[*][mode]ISO-6709:1983-co-ordinate[,[+|-]mmmm|hh:[mm]] references the approximate period of non-visibility of the Sun (solar night length) by default.

All these special texts can be used for at pleasure any geographic point location, i.e. it is possible to determine different astronomical values for any location on the globe, and that for at pleasure any clocktime with a resolution of a single minute within the period of the years AD 1 until AD 9999, that is respected by Gcal.

The selection which value has to be calculated by these special texts is done by specifying the mode part of the preceding argument. Actually, exactly 54 different modes can be used that are represented by the ‘0...9, ‘a...z and ‘A...R characters, and which create different kind of results that are depending on the special text used. First of all, here is a table in which all usable modes are described and explained sufficiently. You can also see from this table, which Sun oriented special text or texts are corresponding to which mode, i.e. cause the determination of an astronomical value as it is described in the table:

Mode Special text Description

0 o, s Calculates the approximate midnight time of the Sun. The astronomical midnight time of the Sun is at that clocktime, when the Sun holds an azimuth (horizontal angular distance between the vertical circle, that passes the Sun, and the North point) of either precisely 0 degrees of precisely 180 degrees (noon line), which depends on the season and the geographical location. At that clocktime, the Sun is close its lowest culmination point, i.e. close the lowest point below or above the horizontal plane the Sun transits during this day.

1 o, s Calculates the approximate noon time of the Sun. The astronomical noon time of the Sun is at that clocktime, when the Sun holds an azimuth of either precisely 180 degrees of precisely 0 degrees (noon line), which depends on the season and the geographical location. At that clocktime, the Sun is close its highest culmination point, i.e. close the highest point above or below the horizontal plane the Sun transits during this day. People of Islamic faith normally pray for the second time on the day during the period, which is between the astronomical noon time of the Sun (or some minutes later) and the Islamic prayer time by the name of Asr. These people commonly use the term Zuhr for this prayer time. The timing of Asr depends on the length of the shadow cast by a vertical pole (gnomon). According to the Shafi school of jurisprudence, Asr begins when the length of the shadow of a vertical pole exceeds the length of the pole. According to the Hanafi school of jurisprudence, Asr begins when the length of the shadow exceeds twice the length of the vertical pole. In both cases, the minimum length of the shadow at astronomical noon time of the Sun is subtracted from the length of the shadow before comparing it with the length of the pole. See Islamic Asr-1 prayer time, and Islamic Asr-2 prayer time, for further details.

2 o Calculates the approximate time when the center of the Sun passes a reference altitude of 0 degrees on a mathematical-geocentric horizon in the morning; thus rising. A mathematical horizon is a purely geometrically-built horizon which disregards the phenomenon of refraction as it arises in reality by the influence of the Earth's atmosphere. A geocentrical horizon is the horizontal plane that passes through the Earth's center, orthogonal to the observer's local vertical. In the further context, the shorter term mathematical horizon is used which actually means the mathematical-geocentric horizon.

2 s Calculates the approximate time when the center of the Sun passes a reference altitude of 0 degrees on a mathematical horizon in the evening; thus setting.

2 u Calculates the approximate period while the center of the Sun is above a reference altitude of 0 degrees on a mathematical horizon; thus is visible.

2 z Calculates the approximate period while the center of the Sun is below a reference altitude of 0 degrees on a mathematical horizon; thus is non-visible.

3 o Calculates the approximate time when the upper limb of the Sun passes a reference altitude of 0 degrees on a mathematical horizon in the morning; thus rising. The above mentioned reference altitude is computed from the value of the Sun's semidiameter as it appear at that clocktime. If the reference altitude that is referring to the Sun's upper limb is converted to a reference altitude that is referring to the Sun's center, this results in a value of about 16 arcminutes below the geocentric horizon.

3 s Calculates the approximate time when the upper limb of the Sun passes a reference altitude of 0 degrees on a mathematical horizon in the evening; thus setting. The above mentioned reference altitude is computed from the value of the Sun's semidiameter as it appear at that clocktime.

3 u Calculates the approximate period while the upper limb of the Sun is above a reference altitude of 0 degrees on a mathematical horizon; thus is visible.

3 z Calculates the approximate period while the upper limb of the Sun is below a reference altitude of 0 degrees on a mathematical horizon; thus is non-visible.

4 o Calculates the approximate time when the center of the Sun passes a reference altitude of 34 arcminutes below the geocentric horizon in the morning; thus rising. The phenomenon of refraction is already respected in this as it arises in reality by the influence of the Earth's atmosphere, and that with the standard value of 34 arcminutes, which can indirectly be changed by using the --atmosphere option. Fixed dates option --atmosphere=air-pressure[,temperature], how to change the base data of the atmosphere, so that the atmospheric conditions as defined by it are used to calculate the amount of refraction.

4 s Calculates the approximate time when the center of the Sun passes a reference altitude of 34 arcminutes below the geocentric horizon in the evening; thus setting. The phenomenon of refraction is already respected in this as it arises in reality by the influence of the Earth's atmosphere, and that with the standard value of 34 arcminutes, which can indirectly be changed by using the --atmosphere option.

4 u Calculates the approximate period while the center of the Sun is above a reference altitude of 34 arcminutes below the geocentric horizon; thus is visible.

4 z Calculates the approximate period while the center of the Sun is below a reference altitude of 34 arcminutes below the geocentric horizon; thus is non-visible.

5 o Calculates the approximate time when the upper limb of the Sun passes a reference altitude of 34 arcminutes below the geocentric horizon in the morning; thus rising. This kind of rise time calculation is done according to the standard calculation method as it is commonly used internationally. The phenomenon of refraction is already respected in this as it arises in reality by the influence of the Earth's atmosphere, and that with the standard value of 34 arcminutes, which can indirectly be changed by using the --atmosphere option. Fixed dates option --atmosphere=air-pressure[,temperature], how to change the base data of the atmosphere, so that the atmospheric conditions as defined by it are used to calculate the amount of refraction. The above mentioned reference altitude is computed from the respective values of the Sun's semidiameter and (standard) refraction as they appear at that clocktime. If the reference altitude that is referring to the Sun's upper limb is converted to a reference altitude that is referring to the Sun's center, this results in a value of about 50 arcminutes below the geocentric horizon.

5 s Calculates the approximate time when the upper limb of the Sun passes a reference altitude of 34 arcminutes below the geocentric horizon in the evening; thus setting. This kind of set time calculation is done according to the standard calculation method as it is commonly used internationally. The phenomenon of refraction is already respected in this as it arises in reality by the influence of the Earth's atmosphere, and that with the standard value of 34 arcminutes, which can indirectly be changed by using the --atmosphere option. The above mentioned reference altitude is computed from the respective values of the Sun's semidiameter and (standard) refraction as they appear at that clocktime. People of Islamic faith normally pray for the second-last time on the day at this clocktime, or some minutes later. These people commonly use the term Maghrib for this prayer time.

5 u Calculates the approximate period while the upper limb of the Sun is above a reference altitude of 34 arcminutes below the geocentric horizon; thus is visible. This kind of visibility period calculation is done according to the standard calculation method as it is commonly used internationally.

5 z Calculates the approximate period while the upper limb of the Sun is above a reference altitude of 34 arcminutes below the geocentric horizon; thus is non-visible. This kind of non-visibility period calculation is done according to the standard calculation method as it is commonly used internationally.

6 o Calculates the approximate time when the center of the Sun passes a reference altitude of 6 degrees below a mathematical horizon in the morning; thus the beginning of civil twilight. The scattered light of the Sun that is remaining at the beginning of the civil twilight phase is in general not yet sufficient for reading outside without artificial illumination.

6 s Calculates the approximate time when the center of the Sun passes a reference altitude of 6 degrees below a mathematical horizon in the evening; thus the ending of civil twilight.

6 u Calculates the approximate period while the center of the Sun is above a reference altitude of 6 degrees below a mathematical horizon; thus the period, while the center of the Sun is always above -6 degrees.

6 z Calculates the approximate period while the center of the Sun is below a reference altitude of 6 degrees below a mathematical horizon; thus the period, while the center of the Sun is always below -6 degrees.

7 o Calculates the approximate time when the center of the Sun passes a reference altitude of 12 degrees below a mathematical horizon in the morning; thus the beginning of nautical twilight. The scattered light of the Sun that is remaining at the beginning of the nautical twilight phase is in general not yet sufficient for navigation using a sea horizon.

7 s Calculates the approximate time when the center of the Sun passes a reference altitude of 12 degrees below a mathematical horizon in the evening; thus the ending of nautical twilight.

7 u Calculates the approximate period while the center of the Sun is above a reference altitude of 12 degrees below a mathematical horizon; thus the period, while the center of the Sun is always above -12 degrees.

7 z Calculates the approximate period while the center of the Sun is below a reference altitude of 12 degrees below a mathematical horizon; thus the period, while the center of the Sun is always below -12 degrees.

8 o Calculates the approximate time when the center of the Sun passes a reference altitude of 15 degrees below a mathematical horizon in the morning; thus the beginning of amateur-astronomical twilight. The scattered light of the Sun that is remaining at the beginning of the amateur-astronomical twilight phase is in general yet so faint that most astronomical observations can be made.

8 s Calculates the approximate time when the center of the Sun passes a reference altitude of 15 degrees below a mathematical horizon in the evening; thus the ending of amateur-astronomical twilight.

8 u Calculates the approximate period while the center of the Sun is above a reference altitude of 15 degrees below a mathematical horizon; thus the period, while the center of the Sun is always above -15 degrees.

8 z Calculates the approximate period while the center of the Sun is below a reference altitude of 15 degrees below a mathematical horizon; thus the period, while the center of the Sun is always below -15 degrees.

8 o Calculates the approximate time when the center of the Sun passes a reference altitude of 18 degrees below a mathematical horizon in the morning; thus the beginning of astronomical twilight. No appreciable scattered sunlight is remaining at the beginning of the astronomical twilight phase, the sky is completely dark yet. People of Islamic faith normally pray for the first time on the day during the period, which is between this clocktime and the time of standard sunrise. These people commonly use the term Fajr for this prayer time. See Standard rise time of the Sun, for further details.

9 s Calculates the approximate time when the center of the Sun passes a reference altitude of 18 degrees below a mathematical horizon in the evening; thus the ending of astronomical twilight. People of Islamic faith normally pray for the last time on the day at this clocktime, or some minutes later. These people commonly use the term Isha for this prayer time.

9 u Calculates the approximate period while the center of the Sun is above a reference altitude of 18 degrees below a mathematical horizon; thus the period, while the center of the Sun is always above -18 degrees.

9 z Calculates the approximate period while the center of the Sun is below a reference altitude of 18 degrees below a mathematical horizon; thus the period, while the center of the Sun is always below -18 degrees.

a o, s Calculates the approximate topocentric, apparent elevation of the Sun, thus the vertical angular distance between the Sun's center and the horizon, in degrees and arcminutes as it happen at civil midnight time. Results with a negative sign signify that the Sun's center is below the horizon at the moment, and results with a positive sign mean that the momentary center of the Sun is above the horizon. Observations of celestial objects that are done from the surface of the Earth yield in topocentrically based data. The locations of the celestial bodies are often at another place if the data is topocentrically determined instead of determine it geocentrically, i.e. at the fictitious center of the Earth. This is mainly caused by the refraction, which raises a celestial body to another location as it is been in reality. Because the terrestrial globe flattens towards the pole caps and therefore cannot be taken as an ideally shaped sphere, the individual Earth radius between the observer's location and the center of the Earth also affects the computation of topocentrically based data.

b o, s Calculates the approximate topocentric, apparent azimuth of the Sun in degrees and arcminutes as it happen at civil midnight time.

c o, s Calculates the approximate topocentric, apparent declination of the Sun, thus the vertical angular distance between the Sun's center and the celestial equator, in degrees and arcminutes as it happen at civil midnight time. Results with a negative sign signify that the Sun's center is below the celestial equator at the moment, and results with a positive sign mean that the momentary center of the Sun is below the celestial equator.

d o, s Calculates the approximate topocentric, apparent ecliptic longitude of the Sun, thus the horizontal angular distance between the Sun's center and the vernal equinox point on the ecliptic (the zodiacal line or Sun's orbit), in degrees and arcminutes as it happen at civil midnight time.

e o, s Calculates the approximate topocentric, apparent right ascension of the Sun, thus the horizontal angular distance between the Sun's center and the hour circle that passes through the vernal equinox point on the ecliptic, as time value in hours and minutes as it happen at civil midnight time.

f o, s Calculates the approximate topocentric, apparent distance of the Sun from the Earth in astronomical units as it happen at civil midnight time. An astronomical unit, abbreviated by ae, is equal to the mean distance of the Sun from the Earth, which is about 149,597,870.691 kilometers.

g o, s Calculates the approximate topocentric, apparent horizontal parallax of the Sun in degrees and arcminutes as it happen at civil midnight time. The horizontal parallax of the Sun specifies the diameter of the Earth as it is seen from the surface of the Sun.

h o, s Calculates the approximate topocentric, apparent semidiameter of the Sun in degrees and arcminutes as it happen at civil midnight time.

i o, s Calculates the approximate refraction of the Earth's atmosphere in degrees and arcminutes as it happen at civil midnight time.

j o, s Calculates the approximate geocentric, apparent elevation of the Sun in degrees and arcminutes as it happen at civil midnight time. Results with a negative sign signify that the Sun's center is below the horizon at the moment, and results with a positive sign mean that the momentary center of the Sun is above the horizon.

k o, s Calculates the approximate geocentric, apparent azimuth of the Sun in degrees and arcminutes as it happen at civil midnight time.

l o, s Calculates the approximate geocentric, apparent declination of the Sun in degrees and arcminutes as it happen at civil midnight time. Results with a negative sign signify that the Sun's center is below the celestial equator at the moment, and results with a positive sign mean that the momentary center of the Sun is above the celestial equator.

m o, s Calculates the approximate geocentric, apparent ecliptic longitude of the Sun in degrees and arcminutes as it happen at civil midnight time.

n o, s Calculates the approximate geocentric, apparent right ascension of the Sun as time value in hours and minutes as it happen at civil midnight time.

o o, s Calculates the approximate geocentric, apparent distance of the Sun from the Earth in astronomical units as it happen at civil midnight time.

p o, s Calculates the approximate geocentric, apparent horizontal parallax of the Sun in degrees and arcminutes as it happen at civil midnight time.

q o, s Calculates the approximate geocentric, apparent semidiameter of the Sun in degrees and arcminutes as it happen at civil midnight time.

r o, s Calculates the approximate delta-t in seconds as it happen at civil midnight time. Delta-t is the difference between the Terrestrial Dynamical time (abbreviated by TDT), that was formerly known as Ephemeris time (abbreviated by ET), and the Universal time (UT). Thus, ‘delta-t == TDT - UT.

s o, s Calculates the approximate, apparent location oriented sidereal time (local sidereal time (LAST), also known as local star time) in hours and minutes as it happen at civil midnight time. A star day is the period between two consecutive upper culminations of the vernal equinox point on the ecliptic in the meridian of the observer's location. Therefore, the local star time is the momentary period, which is past between the last upper culmination of the vernal equinox point in the meridian of the observer's location (the momentary hour angle of the vernal equinox point), thus the right ascension of the stars in the observer's meridian at the moment.

t o, s Outputs the base time as time value in hours and minutes, for which the dynamical, i.e. depending on the respective clocktime, astronomical data and times of the Sun are calculated. Without a given --time-offset=argument option, the astronomical data and times of the Sun are always calculated for 0 o'clock Universal time (UTC/GMT). See Calendar option --time-offset=argument, for further details.

u o, s Calculates the approximate Julian date in days as it happen at civil midnight time. See Julian day number, for further information about the Julian date.

v o, s Calculates the approximate Julian Ephemeris date, thus a Julian date that is corrected by delta-t, in days as it happen at civil midnight time.

w o, s Calculates the approximate difference between true solar time and mean solar time as time value in hours and minutes as it happen at civil midnight time. This so-called equation of time is a correction to be added to the true solar time —as read on a sundial— to obtain the mean solar time. A true solar day is the period between two consecutive lower culminations of the Sun. This entity is taken as the base for deriving the true solar time (as it is also shown by a sundial during the day). A star day is also known as a mean solar day. Because the Sun apparently shifts with respect to the vernal equinox point on the ecliptic due to the Earth's orbit around the Sun, the star day and the true solar day have a different length. As the true Sun namely moves irregularly through the ecliptic, a fictitious mean Sun with a symmetrical motion through the celestial equator is used for deriving the mean solar time. So, this difference in time is a consequence of the ellipticity and tilt of the Earth's orbit, causing the irregular apparent movement of the Sun across the sky.

x o, s Calculates the difference of the approximate topocentric, apparent elevation of Sun and Moon (delta), at which the Sun is used as the reference point, in degrees and arcminutes as it happen at civil midnight time. Results with a negative sign signify that the momentary center of the Sun is at an elevation that is below the momentary elevation of the Moon's center; thus the Sun is lower than the Moon. Results with a positive sign signify that the momentary center of the Sun is at an elevation that is above the momentary elevation of the Moon's center; thus the Sun is higher than the Moon.

y o, s Calculates the difference of the approximate topocentric, apparent azimuth of Sun and Moon (delta), at which the Sun is used as the reference point, in degrees and arcminutes as it happen at civil midnight time. The result specifies the horizontal angular distance, by which the momentary center of the Sun is distant from the momentary Moon's center, and that measured at the vertical circles that pass the Sun and the North point and the Moon and the North point. Results with a negative sign signify that the Moon is to the right (clockwise) of the Sun if one looks to the Sun — or alternatively expressed, that the Sun is to the left (anti-clockwise) of the Moon. Results with a positive sign signify that the Moon is to the left (anti-clockwise) of the Sun if one looks to the Sun — or alternatively expressed, that the Sun is to the right (clockwise) of the Moon.

z o, s Calculates the difference of the approximate geocentric, apparent elevation of Sun and Moon (delta), at which the Sun is used as the reference point, in degrees and arcminutes as it happen at civil midnight time.

A o, s Calculates the difference of the approximate geocentric, apparent azimuth of Sun and Moon (delta), at which the Sun is used as the reference point, in degrees and arcminutes as it happen at civil midnight time.

B o Calculates the difference of the approximate topocentric, apparent elevation of Sun and Moon (delta), at which the Sun is used as the reference point, in degrees and arcminutes as it happen at standard rise time of the Sun. See Standard rise time of the Sun, for further details.

B s Calculates the difference of the approximate topocentric, apparent elevation of Sun and Moon (delta), at which the Sun is used as the reference point, in degrees and arcminutes as it happen at standard set time of the Sun. See Standard set time of the Sun, for further details.

C o Calculates the difference of the approximate topocentric, apparent azimuth of Sun and Moon (delta), at which the Sun is used as the reference point, in degrees and arcminutes as it happen at standard rise time of the Sun. See Standard rise time of the Sun, for further details.

C s Calculates the difference of the approximate topocentric, apparent azimuth of Sun and Moon (delta), at which the Sun is used as the reference point, in degrees and arcminutes as it happen at standard set time of the Sun. See Standard set time of the Sun, for further details.

D o Calculates the difference of the approximate geocentric, apparent elevation of Sun and Moon (delta), at which the Sun is used as the reference point, in degrees and arcminutes as it happen at standard rise time of the Sun. See Standard rise time of the Sun, for further details.

D s Calculates the difference of the approximate geocentric, apparent elevation of Sun and Moon (delta), at which the Sun is used as the reference point, in degrees and arcminutes as it happen at standard set time of the Sun. See Standard set time of the Sun, for further details.

E o Calculates the difference of the approximate geocentric, apparent azimuth of Sun and Moon (delta), at which the Sun is used as the reference point, in degrees and arcminutes as it happen at standard rise time of the Sun. See Standard rise time of the Sun, for further details.

E s Calculates the difference of the approximate geocentric, apparent azimuth of Sun and Moon (delta), at which the Sun is used as the reference point, in degrees and arcminutes as it happen at standard set time of the Sun. See Standard set time of the Sun, for further details.

F o, s Calculates the difference of the approximate astronomical midnight times of Sun and Moon (delta), at which the Sun is used as the reference point, as time value in hours and minutes as it happen at astronomical midnight time of the Sun. Results with a negative sign signify that the astronomical midnight time of the Sun is earlier than the astronomical midnight time of the Moon; thus the solar midnight is before the lunar midnight. Results with a positive sign signify that the astronomical midnight time of the Sun is later than the astronomical midnight time of the Moon; thus the solar midnight is after the lunar midnight. See Astronomical midnight time of the Sun, and Astronomical midnight time of the Moon, for further details.

G o, s Calculates the difference of the approximate astronomical noon times of Sun and Moon (delta), at which the Sun is used as the reference point, as time value in hours and minutes as it happen at astronomical noon time of the Sun. Results with a negative sign signify that the astronomical noon time of the Sun is earlier than the astronomical noon time of the Moon; thus the solar noon is before the lunar noon. Results with a positive sign signify that the astronomical noon time of the Sun is later than the astronomical noon time of the Moon; thus the solar noon is after the lunar noon. See Astronomical noon time of the Sun, and Astronomical noon time of the Moon, for further details.

H o Calculates the difference of the approximate standard rise times of Sun and Moon (delta), at which the Sun is used as the reference point, as time value in hours and minutes as it happen at standard rise time of the Sun. Results with a negative sign signify that the standard rise time of the Sun is earlier than the standard rise time of the Moon; thus the sunrise is before the moonrise. Results with a positive sign signify that the standard rise time of the Sun is later than the standard rise time of the Moon; thus the sunrise is after the moonrise. See Standard rise time of the Sun, and Standard rise time of the Moon, for further details.

H s Calculates the difference of the approximate standard set times of Sun and Moon (delta), at which the Sun is used as the reference point, as time value in hours and minutes as it happen at standard set time of the Sun. Results with a negative sign signify that the standard set time of the Sun is earlier than the standard set time of the Moon; thus the sunset is before the moonset. Results with a positive sign signify that the standard set time of the Sun is later than the standard set time of the Moon; thus the sunset is after the moonset. See Standard set time of the Sun, and Standard set time of the Moon, for further details.

I o, s Calculates the approximate topocentric, apparent elevation of the Sun in degrees and arcminutes as it happen at astronomical midnight time of the Sun (topocentric midnight height). See Astronomical midnight time of the Sun, for further details.

J o, s Calculates the approximate topocentric, apparent elevation of the Sun in degrees and arcminutes as it happen at astronomical midnight time of the Sun (topocentric midnight height). See Astronomical noon time of the Sun, for further details.

K o Calculates the approximate topocentric, apparent elevation of the Sun in degrees and arcminutes as it happen at standard rise time of the Sun (topocentric rise height). See Standard rise time of the Sun, for further details.

K s Calculates the approximate topocentric, apparent elevation of the Sun in degrees and arcminutes as it happen at standard set time of the Sun (topocentric set height). See Standard set time of the Sun, for further details.

L o Calculates the approximate topocentric, apparent azimuth of the Sun in degrees and arcminutes as it happen at standard rise time of the Sun (topocentric rise azimuth). The horizontal angular distance between the topocentric rise azimuth and the East direction is also known as the topocentric morning width of the Sun. See Standard rise time of the Sun, for further details.

L s Calculates the approximate topocentric, apparent azimuth of the Sun in degrees and arcminutes as it happen at standard set time of the Sun (topocentric set azimuth). The horizontal angular distance between the topocentric set azimuth and the West direction is also known as the topocentric evening width of the Sun. See Standard set time of the Sun, for further details.

M o, s Calculates the approximate geocentric, apparent elevation of the Sun in degrees and arcminutes as it happen at astronomical midnight time of the Sun (geocentric midnight height). See Astronomical midnight time of the Sun, for further details.

N o, s Calculates the approximate geocentric, apparent elevation of the Sun in degrees and arcminutes as it happen at astronomical midnight time of the Sun (geocentric midnight height). See Astronomical noon time of the Sun, for further details.

O o Calculates the approximate geocentric, apparent elevation of the Sun in degrees and arcminutes as it happen at standard rise time of the Sun (geocentric rise height). See Standard rise time of the Sun, for further details.

O s Calculates the approximate geocentric, apparent elevation of the Sun in degrees and arcminutes as it happen at standard set time of the Sun (geocentric set height). See Standard set time of the Sun, for further details.

P o Calculates the approximate geocentric, apparent azimuth of the Sun in degrees and arcminutes as it happen at standard rise time of the Sun (geocentric rise azimuth). The horizontal angular distance between the geocentric rise azimuth and the East direction is also known as the geocentric morning width of the Sun. See Standard rise time of the Sun, for further details.

P s Calculates the approximate geocentric, apparent azimuth of the Sun in degrees and arcminutes as it happen at standard set time of the Sun (geocentric set azimuth). The horizontal angular distance between the geocentric set azimuth and the West direction is also known as the geocentric evening width of the Sun. See Standard set time of the Sun, for further details.

Q o Calculates the approximate time when the length of the shadow cast by a vertical pole in the forenoon is equal the length of the pole. Nevertheless, the minimum length of the shadow is subtracted from the length of the shadow before comparing it with the length of the pole. See Fixed dates option --adjust-value=argument, how to change the shadow length factor.

Q s Calculates the approximate time when the length of the shadow cast by a vertical pole in the afternoon is equal the length of the pole. Nevertheless, the minimum length of the shadow is subtracted from the length of the shadow before comparing it with the length of the pole. People of Islamic faith, and that the people holding the Shafi school of jurisprudence, normally pray for the third time on the day at this clocktime, or some minutes later. These people commonly use the term Asr for this prayer time. See Astronomical noon time of the Sun, for more information. And note Fixed dates option --adjust-value=argument, how to change the shadow length factor.

Q u Calculates the approximate period while the center of the Sun is above a reference altitude, at which the length of the shadow cast by a vertical pole is of single or shorter length than the pole itself.

Q z Calculates the approximate period while the center of the Sun is below a reference altitude, at which a vertical pole either casts no shadow anymore, or casts a shadow that is longer than the single length of the pole itself.

R o Calculates the approximate time when the length of the shadow cast by a vertical pole at forenoon is twice the length of the pole. Nevertheless, the minimum length of the shadow is subtracted from the length of the shadow before comparing it with the length of the pole. See Fixed dates option --adjust-value=argument, how to change the shadow length factor.

R s Calculates the approximate time when the length of the shadow cast by a vertical pole in the afternoon is twice the length of the pole. Nevertheless, the minimum length of the shadow is subtracted from the length of the shadow before comparing it with the length of the pole. People of Islamic faith, and that the people holding the Hanafi school of jurisprudence, normally pray for the third time on the day at this clocktime, or some minutes later. These people commonly use the term Asr for this prayer time. See Astronomical noon time of the Sun, for more information. And note Fixed dates option --adjust-value=argument, how to change the shadow length factor.

R u Calculates the approximate period while the center of the Sun is above a reference altitude, at which the length of the shadow cast by a vertical pole is of double or shorter length than the pole itself.

R z Calculates the approximate period while the center of the Sun is below a reference altitude, at which a vertical pole either casts no shadow anymore, or casts a shadow that is longer than twice the length of the pole itself.

If no mode is given, Gcal automatically uses that mode, which is enabled by the mode character ‘5’. If a mode character is given that is not according to one of the ‘0...9, ‘a...z and ‘A...R characters, Gcal also automatically uses that mode, which is enabled by the mode character ‘5’.

Gcal represents the Sun oriented special texts depending on the selected mode using the following types and styles:

  1. Unsigned decimal based rational number value
    Unsigned decimal based rational number values are represented using the n.n... format by default. A ‘*’ character that is directly given before some mode characters causes Gcal to represent the value for another quantity. For the mode characters, which
    1. cause the calculation of Earth/Sun or Earth/Moon distances, the calculated distance is represented in kilometers.
    2. cause the calculation of phase angles of the Moon, the calculated phase angle is represented as a phase value in percents.

    If definite events happen, Gcal displays special event oriented texts instead of using the previously described representations. See Event texts of the Sun oriented special texts, where you can find the event oriented texts that are created for clocktime values, which are schematically and analogously used for the type of representation as it is described here.

  2. Signed decimal based rational number value
    Signed decimal based rational number values are represented using the +|-n.n... format by default. A ‘*’ character that is directly given before a mode character causes Gcal not to represent such values using another style.

    If definite events happen, Gcal displays special event oriented texts instead of using the previously described representations. See Event texts of the Sun oriented special texts, where you can find the event oriented texts that are created for clocktime values, which are schematically and analogously used for the type of representation as it is described here.

  3. Clocktime value
    Clocktime values are represented in hours and minutes, and that in the hh:mm 24-hour format by default. A ‘*’ character that is directly given before a mode character causes Gcal to represent the clocktime value using the 12-hour format, thus to provide it with a time suffix. See Actual local time %t[argument] special text, for more details about the above mentioned time value template.

    If definite events happen, Gcal displays special event oriented texts instead of using the previously described representations:

  4. Unsigned time value
    Unsigned time values, which mostly denote a period or interval of time, are represented in hours and minutes using the hhhmm' format by default. A ‘*’ character that is directly given before a mode character causes Gcal to represent the time value using another style, and that in decimal hours, i.e. in the hh.h... format.

    If definite events happen, Gcal displays special event oriented texts instead of using the previously described representations. See Event texts of the Sun oriented special texts, where you can find the event oriented texts that are created for clocktime values, which are schematically and analogously used for the type of representation as it is described here.

  5. Signed time value
    Signed time values, which mostly denote a period or interval of time, are represented in hours and minutes using the +|-hhhmm' format by default. A ‘*’ character that is directly given before a mode character causes Gcal to represent the time value using another style, and that in decimal hours, i.e. in the +|-hh.h... format.

    If definite events happen, Gcal displays special event oriented texts instead of using the previously described representations. See Event texts of the Sun oriented special texts, where you can find the event oriented texts that are created for clocktime values, which are schematically and analogously used for the type of representation as it is described here.

  6. Unsigned angular value
    Unsigned angular values are represented in degrees and arcminutes using the ddddmm' format by default. A ‘*’ character that is directly given before a mode character causes Gcal to represent the angular value using another style, and that in decimal degrees, i.e. in the ddd.d... format.

    If definite events happen, Gcal displays special event oriented texts instead of using the previously described representations. See Event texts of the Sun oriented special texts, where you can find the event oriented texts that are created for clocktime values, which are schematically and analogously used for the type of representation as it is described here.

  7. Signed angular value
    Signed angular values are represented in degrees and arcminutes using the +|-ddddmm' format by default. A ‘*’ character that is directly given before a mode character causes Gcal to represent the angular value using another style, and that in decimal degrees, i.e. in the +|-ddd.d... format.

    If definite events happen, Gcal displays special event oriented texts instead of using the previously described representations. See Event texts of the Sun oriented special texts, where you can find the event oriented texts that are created for clocktime values, which are schematically and analogously used for the type of representation as it is described here.

After the optional style and mode characters, the latitude and longitude of the geographic co-ordinates follows, for which the calculations must be made. They must be conform the ISO-6709:1983 standard representation of latitude and longitude for geographic point locations, so that the co-ordinate has to be declared like this:

All components of the co-ordinates must have leadings zeroes in case they have less digits than the templates shown above. Declared decimal seconds are not respected by Gcal. Heights which have a negative sign remain unrespected if Gcal determinates Sun and Moon data and times, respectively. In such a case, Gcal always uses the height +0. Latitude and longitude co-ordinates, and the height of the observer's location are connected without any separating characters, like ‘+40-075+61’, ‘+401213.1-0750015.1’ or ‘+40.20361-075.00417+0061’. See the pertinent literature for more details.

A time value [+|-]mmmm|hh:[mm], which is separated by a ‘,’ character, may trail the co-ordinate. Such a time value informs Gcal, about how many minutes mmmm respectively hours hh and minutes mm the geographic location is displaced from Universal time (UTC/GMT). This time displacement value defines the timezone, which is actually valid for this location. If summer- and wintertimes are respected for the location, you should include that change in time into the timezone value for the period in which the summertime is valid, by which the clock is put on during the summertime period — such a change is either subtracted from the timezone value for locations West of the prime meridian (Greenwich), or it is added for locations East of the prime meridian, because Gcal is actually unable to perform such operations automatically! See Actual local time %t[argument] special text, for more details about the above mentioned time value template. If no time displacement value is specified for a given co-ordinate, Gcal assumes a time displacement value of 0, which is equal to the actual Universal time (UTC/GMT).

The following table informs you about which type of representation is caused by a mode. The previously defined numbering scheme, as it has been used for the introduction of the types of representations, is used as key value in the column that holds the type of representation. The table also contains a column that shows whether a mode enables dynamical values, i.e. values that are depending on the respective clocktime (if you use the --time-offset=argument option, you can change the respective clocktime that is used for calculating such values). In a next table column, it is listed whether the given co-ordinate of the location influences the determination of a value, and the last column of the table gives you the information whether a given timezone value affects the values determination:

Mode Representation Type Dynamical Co-ordinate Timezone

0 3 No Yes Yes
1 3 No Yes Yes
2 3 or 4 No Yes Yes
3 3 or 4 No Yes Yes
4 3 or 4 No Yes Yes
5 3 or 4 No Yes Yes
6 3 or 4 No Yes Yes
7 3 or 4 No Yes Yes
8 3 or 4 No Yes Yes
9 3 or 4 No Yes Yes
a 7 Yes Yes Yes
b 6 Yes Yes Yes
c 7 Yes Yes Yes
d 6 Yes Yes Yes
e 4 Yes Yes Yes
f 1 or 1a Yes Yes Yes
g 6 Yes Yes Yes
h 6 Yes Yes Yes
i 6 Yes No No
j 7 Yes Yes Yes
k 6 Yes Yes Yes
l 7 Yes Yes Yes
m 6 Yes Yes Yes
n 4 Yes Yes Yes
o 1 or 1a Yes Yes Yes
p 6 Yes Yes Yes
q 6 Yes Yes Yes
r 2 Yes No No
s 3 Yes Yes Yes
t 3 Yes No No
u 1 Yes No No
v 1 Yes No No
w 5 Yes No Yes
x 7 Yes Yes Yes
y 7 Yes Yes Yes
z 7 Yes Yes Yes
A 7 Yes Yes Yes
B 7 No Yes Yes
C 7 No Yes Yes
D 7 No Yes Yes
E 7 No Yes Yes
F 5 No Yes Yes
G 5 No Yes Yes
H 5 No Yes Yes
I 7 No Yes Yes
J 7 No Yes Yes
K 7 No Yes Yes
L 6 No Yes Yes
M 7 No Yes Yes
N 7 No Yes Yes
O 7 No Yes Yes
P 6 No Yes Yes
Q 3 or 4 No Yes Yes
R 3 or 4 No Yes Yes

And now some examples to these special texts:

The text ‘Sunrise at %o+5158+00738,120  in MS, BRD will be expanded to
==> ‘Sunrise at 05:16 in MS, BRD, in case the actual system date is the 1st June 1998.
The text ‘Sunset at %s*5+5158+00738,120  in MS, BRD will be expanded to
==> ‘Sunset at 09:39pm in MS, BRD, in case the actual system date is the 1st June 1998.
The text ‘Sun visible %u5+5158+00738,120  in MS, BRD will be expanded to
==> ‘Sun visible 16h24' in MS, BRD, in case the actual system date is the 1st June 1998.
The text ‘Sun non-visible %z*+5158+00738,120  in MS, BRD will be expanded to
==> ‘Sun non-visible 7.607 in MS, BRD, in case the actual system date is the 1st June 1998.
The text ‘Sun azimuth 0 o'clock=%s*a+5158+00738,120  in MS, BRD will be expanded to
==> ‘Sun azimuth 0 o'clock=339d16' in MS, BRD, in case the actual system date is the 1st June 1998.
The text ‘Equation of time %ot+00+000=%o*w+00+000,120  BRD will be expanded to
==> ‘Equation of time +16h00'=+00h02'13.201" BRD, in case you call Gcal with the --time-offset=16: and --precise options and the actual system date is the 1st June 1998.
The text ‘Julian date at %ot+00+000 =%ou+00+000 will be expanded to
==> ‘Julian date at +10h15'=2450965.927, in case you call Gcal with the --time-offset=10:15 option and the actual system date is the 1st June 1998.

Here is a list that reports about the used reference systems in a short manner, describes other aspects that are unmentioned now, and informs about the lacks and limitations that are existing for the Sun oriented special texts:

Please also note the following references:

All Sun oriented special texts must always be trailed by a whitespace character which is removed in output!