Zmanim.AstronomicalCalendar Class Reference

A calendar that calculates astronomical time calculations such as sunrise and sunset times. This class contains a Calendar and can therefore use the standard Calendar functionality to change dates etc. The calculation engine used to calculate the astronomical times can be changed to a different implementation by implementing the AstronomicalCalculator and setting it with the AstronomicalCalculator. A number of different implementations are included in the util package
Note: There are times when the algorithms can't calculate proper values for sunrise, sunset and twilight. This is usually caused by trying to calculate times for areas either very far North or South, where sunrise / sunset never happen on that date. This is common when calculating twilight with a deep dip below the horizon for locations as south of the North Pole as London in the northern hemisphere. The sun never reaches this dip at certain times of the year. When the calculations encounter this condition a null will be returned when a DateTime is expected and long.MinValue when a long is expected. The reason that Exceptions are not thrown in these cases is because the lack of a rise/set or twilight is not an exception, but expected in many parts of the world. Here is a simple example of how to use the API to calculate sunrise:
First create the Calendar for the location you would like to calculate:

        string locationName = "Lakewood, NJ"
        double latitude = 40.0828; //Lakewood, NJ
        double longitude = -74.2094; //Lakewood, NJ
        double elevation = 20; // optional elevation correction in Meters
        ITimeZone timeZone = new JavaTimeZone("America/New_York");
        GeoLocation location = new GeoLocation(locationName, latitude, longitude,
        elevation, timeZone);
        AstronomicalCalendar ac = new AstronomicalCalendar(location);

You can set the Date and Location on the constructor (or else it will default the the current day).

        AstronomicalCalendar ac = new AstronomicalCalendar(new DateTime(2010, 2, 8), location);

Or you can set the DateTime by calling.

        ac.DateWithLocation.Date = new DateTime(2010, 2, 8);

To get the time of sunrise

        Date sunrise = ac.getSunrise();

More...

Inheritance diagram for Zmanim.AstronomicalCalendar:

List of all members.

Public Member Functions
	AstronomicalCalendar ()
	AstronomicalCalendar (IGeoLocation geoLocation)
	AstronomicalCalendar (DateTime dateTime, IGeoLocation geoLocation)
virtual object	Clone ()
	Creates a new object that is a copy of the current instance. Note: If the See also: Zmanim.TimeZone.ITimeZone in the cloned GeoLocation will be changed from the original, it is critical that DateWithLocation. TimeZone be set in order for the AstronomicalCalendar to output times in the expected offset after being cloned.
virtual DateTime	GetSunrise ()
	The getSunrise method Returns a `DateTime` representing the sunrise time. The zenith used for the calculation uses See also: GEOMETRIC_ZENITH geometric zenithof 90°. This is adjusted by the See also: AstronomicalCalculator, Calculator.AstronomicalCalculator.AdjustZenith that adds approximately 50/60 of a degree to account for 34 archminutes of refraction and 16 archminutes for the sun's radius for a total of 90.83333°. See documentation for the specific implementation of the See also: AstronomicalCalculator that you are using.
virtual DateTime	GetSeaLevelSunrise ()
	Method that returns the sunrise without correction for elevation. Non-sunrise and sunset calculations such as dawn and dusk, depend on the amount of visible light, something that is not affected by elevation. This method returns sunrise calculated at sea level. This forms the base for dawn calculations that are calculated as a dip below the horizon before sunrise.
virtual DateTime	GetBeginCivilTwilight ()
	A method to return the the beginning of civil twilight (dawn) using a zenith of See also: CIVIL_ZENITH 96°.
virtual DateTime	GetBeginNauticalTwilight ()
virtual DateTime	GetBeginAstronomicalTwilight ()
virtual DateTime	GetSunset ()
	The getSunset method Returns a `DateTime` representing the sunset time. The zenith used for the calculation uses geometric zenith of 90°. This is adjusted by the AstronomicalCalculator that adds approximately 50/60 of a degree to account for 34 archminutes of refraction and 16 archminutes for the sun's radius for a total of 90.83333°. See documentation for the specific implementation of the AstronomicalCalculator that you are using. Note: In certain cases the calculates sunset will occur before sunrise. This will typically happen when a timezone other than the local timezone is used (calculating Los Angeles sunset using a GMT timezone for example). In this case the sunset date will be incremented to the following date.
virtual DateTime	GetSeaLevelSunset ()
	Method that returns the sunset without correction for elevation. Non-sunrise and sunset calculations such as dawn and dusk, depend on the amount of visible light, something that is not affected by elevation. This method returns sunset calculated at sea level. This forms the base for dusk calculations that are calculated as a dip below the horizon after sunset.
virtual DateTime	GetEndCivilTwilight ()
	A method to return the the end of civil twilight using a zenith of 96°.
virtual DateTime	GetEndNauticalTwilight ()
	A method to return the the end of nautical twilight using a zenith of 102°.
virtual DateTime	GetEndAstronomicalTwilight ()
	A method to return the the end of astronomical twilight using a zenith of 108°.
virtual DateTime	GetTimeOffset (DateTime time, double offset)
	Utility method that returns a date offset by the offset time passed in. This method casts the offset as a long and calls GetTimeOffset(System.DateTime,long).
virtual DateTime	GetTimeOffset (DateTime time, long offset)
	A utility method to return a date offset by the offset time passed in.
virtual DateTime	GetSunriseOffsetByDegrees (double offsetZenith)
	A utility method to return the time of an offset by degrees below or above the horizon of sunrise.
virtual DateTime	GetSunsetOffsetByDegrees (double offsetZenith)
virtual double	GetUtcSunrise (double zenith)
	Method that returns the sunrise in UTC time without correction for time zone offset from GMT and without using daylight savings time.
virtual double	GetUtcSeaLevelSunrise (double zenith)
	Method that returns the sunrise in UTC time without correction for time zone offset from GMT and without using daylight savings time. Non-sunrise and sunset calculations such as dawn and dusk, depend on the amount of visible light, something that is not affected by elevation. This method returns UTC sunrise calculated at sea level. This forms the base for dawn calculations that are calculated as a dip below the horizon before sunrise.
virtual double	GetUtcSunset (double zenith)
	Method that returns the sunset in UTC time without correction for time zone offset from GMT and without using daylight savings time.
virtual double	GetUtcSeaLevelSunset (double zenith)
	Method that returns the sunset in UTC time without correction for elevation, time zone offset from GMT and without using daylight savings time. Non-sunrise and sunset calculations such as dawn and dusk, depend on the amount of visible light, something that is not affected by elevation. This method returns UTC sunset calculated at sea level. This forms the base for dusk calculations that are calculated as a dip below the horizon after sunset.
virtual long	GetTemporalHour ()
	Method to return a temporal (solar) hour. The day from sunrise to sunset is split into 12 equal parts with each one being a temporal hour.
virtual long	GetTemporalHour (DateTime sunrise, DateTime sunset)
	Utility method that will allow the calculation of a temporal (solar) hour based on the sunrise and sunset passed to this method.
virtual DateTime	GetSunTransit ()
virtual double	GetSunriseSolarDipFromOffset (double minutes)
	Will return the dip below the horizon before sunrise that matches the offset minutes on passed in. For example passing in 72 minutes for a calendar set to the equinox in Jerusalem returns a value close to 16.1° Please note that this method is very slow and inefficient and should NEVER be used in a loop. TODO: Improve efficiency.
virtual double	GetSunsetSolarDipFromOffset (double minutes)
	Will return the dip below the horizon after sunset that matches the offset minutes on passed in. For example passing in 72 minutes for a calendar set to the equinox in Jerusalem returns a value close to 16.1° Please note that this method is very slow and inefficient and should NEVER be used in a loop. TODO: Improve efficiency.
override string	ToString ()
override bool	Equals (object obj)
	Determines whether the specified System.Object is equal to this instance.
override int	GetHashCode ()
	Returns a hash code for this instance.
Public Attributes
const double	GEOMETRIC_ZENITH = 90
	90° below the vertical. Used for certain calculations. Note : it is important to note the distinction between this zenith and the adjusted zenith used for some solar calculations. This 90 zenith is only used because some calculations in some subclasses are historically calculated as an offset in reference to 90. /summary>
const double	CIVIL_ZENITH = 96
	Sun's zenith at civil twilight (96°).
const double	NAUTICAL_ZENITH = 102
	Sun's zenith at nautical twilight (102°).
const double	ASTRONOMICAL_ZENITH = 108
	Sun's zenith at astronomical twilight (108°).
Protected Member Functions
virtual DateTime	GetTimeOffset (DateTime?time, double offset)
virtual DateTime	GetTimeOffset (DateTime?time, long offset)
virtual long	GetTemporalHour (DateTime?sunrise, DateTime?sunset)
virtual internal DateTime	GetDateFromTime (double time)
Properties
virtual IAstronomicalCalculator	AstronomicalCalculator `[get, set]`
	Gets or Sets the current AstronomicalCalculator set.
virtual IDateWithLocation	DateWithLocation `[get, set]`
	Gets or Sets the Date and Location to be used in the calculations.

Detailed Description

A calendar that calculates astronomical time calculations such as sunrise and sunset times. This class contains a Calendar and can therefore use the standard Calendar functionality to change dates etc. The calculation engine used to calculate the astronomical times can be changed to a different implementation by implementing the AstronomicalCalculator and setting it with the AstronomicalCalculator. A number of different implementations are included in the util package
Note: There are times when the algorithms can't calculate proper values for sunrise, sunset and twilight. This is usually caused by trying to calculate times for areas either very far North or South, where sunrise / sunset never happen on that date. This is common when calculating twilight with a deep dip below the horizon for locations as south of the North Pole as London in the northern hemisphere. The sun never reaches this dip at certain times of the year. When the calculations encounter this condition a null will be returned when a DateTime is expected and long.MinValue when a long is expected. The reason that Exceptions are not thrown in these cases is because the lack of a rise/set or twilight is not an exception, but expected in many parts of the world. Here is a simple example of how to use the API to calculate sunrise:
First create the Calendar for the location you would like to calculate:

        string locationName = "Lakewood, NJ"
        double latitude = 40.0828; //Lakewood, NJ
        double longitude = -74.2094; //Lakewood, NJ
        double elevation = 20; // optional elevation correction in Meters
        ITimeZone timeZone = new JavaTimeZone("America/New_York");
        GeoLocation location = new GeoLocation(locationName, latitude, longitude,
        elevation, timeZone);
        AstronomicalCalendar ac = new AstronomicalCalendar(location);

You can set the Date and Location on the constructor (or else it will default the the current day).

        AstronomicalCalendar ac = new AstronomicalCalendar(new DateTime(2010, 2, 8), location);

Or you can set the DateTime by calling.

        ac.DateWithLocation.Date = new DateTime(2010, 2, 8);

To get the time of sunrise

        Date sunrise = ac.getSunrise();

<author>Eliyahu Hershfeld</author>

Constructor & Destructor Documentation

Zmanim.AstronomicalCalendar.AstronomicalCalendar ( )

summary> A constructor that takes in as a parameter geolocation information /summary> param name = "geoLocation"> The location information used for astronomical calculating sun times.

Zmanim.AstronomicalCalendar.AstronomicalCalendar ( IGeoLocation geoLocation )

summary> A constructor that takes in as a parameter geolocation information /summary> param name="dateTime">The DateTime

param name = "geoLocation"> The location information used for astronomical calculating sun times.

Member Function Documentation

virtual object Zmanim.AstronomicalCalendar.Clone ( ) [virtual]

Creates a new object that is a copy of the current instance. Note: If the

See also:: Zmanim.TimeZone.ITimeZone

in the cloned GeoLocation will be changed from the original, it is critical that DateWithLocation. TimeZone be set in order for the AstronomicalCalendar to output times in the expected offset after being cloned.

Returns:: A new object that is a copy of this instance.

override bool Zmanim.AstronomicalCalendar.Equals ( object obj )

Determines whether the specified System.Object is equal to this instance.

Parameters:

obj

The System.Object to compare with this instance.

Returns:: true if the specified System.Object is equal to this instance; otherwise, false.

Exceptions:

T:System.NullReferenceException

The obj parameter is null.

Reimplemented in Zmanim.ZmanimCalendar.

virtual DateTime Zmanim.AstronomicalCalendar.GetBeginCivilTwilight ( ) [virtual]

A method to return the the beginning of civil twilight (dawn) using a zenith of

See also:: CIVIL_ZENITH

96°.

Returns:: The DateTime of the beginning of civil twilight using a zenith of 96°. If the calculation can't be computed (see explanation on top of the page), null will be returned.

See also:: CIVIL_ZENITH

summary> A method to return the the beginning of nautical twilight using a zenith of 102°. /summary> returns> The DateTime of the beginning of nautical twilight using a zenith of 102°. If the calculation can't be computed (see explanation on top of the page), null will be returned.

seealso cref = "NAUTICAL_ZENITH" />

virtual DateTime Zmanim.AstronomicalCalendar.GetBeginNauticalTwilight ( ) [virtual]

summary> A method that returns the the beginning of astronomical twilight using a zenith of 108°. /summary> returns> The DateTime of the beginning of astronomical twilight using a zenith of 108°. If the calculation can't be computed (see explanation on top of thepage), null will be returned.

seealso cref = "ASTRONOMICAL_ZENITH" />

virtual DateTime Zmanim.AstronomicalCalendar.GetEndAstronomicalTwilight ( ) [virtual]

A method to return the the end of astronomical twilight using a zenith of 108°.

Returns:: The The DateTime of the end of astronomical twilight using a zenith of 108°. If the calculation can't be computed (see explanation on top of thepage), null will be returned.

See also:: ASTRONOMICAL_ZENITH

virtual DateTime Zmanim.AstronomicalCalendar.GetEndCivilTwilight ( ) [virtual]

A method to return the the end of civil twilight using a zenith of 96°.

Returns:

The DateTime of the end of civil twilight using a zenith of

See also:: CIVIL_ZENITH

96°

. If the calculation can't be computed (see explanation on top of thepage), null will be returned.

See also:: CIVIL_ZENITH

virtual DateTime Zmanim.AstronomicalCalendar.GetEndNauticalTwilight ( ) [virtual]

A method to return the the end of nautical twilight using a zenith of 102°.

Returns:

The DateTime of the end of nautical twilight using a zenith of

See also:: NAUTICAL_ZENITH

102°

. If the calculation can't be computed (see explanation on top of thepage), null will be returned.

See also:: NAUTICAL_ZENITH

override int Zmanim.AstronomicalCalendar.GetHashCode ( )

Returns a hash code for this instance.

Returns:: A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.

Reimplemented in Zmanim.ComplexZmanimCalendar, and Zmanim.ZmanimCalendar.

virtual DateTime Zmanim.AstronomicalCalendar.GetSeaLevelSunrise ( ) [virtual]

Method that returns the sunrise without correction for elevation. Non-sunrise and sunset calculations such as dawn and dusk, depend on the amount of visible light, something that is not affected by elevation. This method returns sunrise calculated at sea level. This forms the base for dawn calculations that are calculated as a dip below the horizon before sunrise.

Returns:: the DateTime representing the exact sea-level sunrise time. If the calculation can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does not set, a null will be returned. See detailed explanation on top of the page.

See also:: GetSunrise, GetUtcSeaLevelSunrise

virtual DateTime Zmanim.AstronomicalCalendar.GetSeaLevelSunset ( ) [virtual]

Method that returns the sunset without correction for elevation. Non-sunrise and sunset calculations such as dawn and dusk, depend on the amount of visible light, something that is not affected by elevation. This method returns sunset calculated at sea level. This forms the base for dusk calculations that are calculated as a dip below the horizon after sunset.

Returns:: the DateTime representing the exact sea-level sunset time. If the calculation can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does not set, a null will be returned. See detailed explanation on top of the page.

See also:: GetSunset, GetUtcSeaLevelSunset

virtual DateTime Zmanim.AstronomicalCalendar.GetSunrise ( ) [virtual]

The getSunrise method Returns a DateTime representing the sunrise time. The zenith used for the calculation uses

See also:: GEOMETRIC_ZENITH

geometric zenithof 90°. This is adjusted by the

See also:: AstronomicalCalculator, Calculator.AstronomicalCalculator.AdjustZenith

that adds approximately 50/60 of a degree to account for 34 archminutes of refraction and 16 archminutes for the sun's radius for a total of 90.83333°. See documentation for the specific implementation of the

See also:: AstronomicalCalculator

that you are using.

Returns:: the DateTime representing the exact sunrise time. If the calculation can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does not set, a null will be returned. See detailed explanation on top of the page.

See also:: Calculator.AstronomicalCalculator.AdjustZenith

Implements Zmanim.IAstronomicalCalendar.

virtual DateTime Zmanim.AstronomicalCalendar.GetSunriseOffsetByDegrees ( double offsetZenith ) [virtual]

A utility method to return the time of an offset by degrees below or above the horizon of sunrise.

Parameters:

offsetZenith

the degrees before GetSunrise to use in the calculation. For time after sunrise use negative numbers.

Returns:

The

See also:: DateTime

of the offset after (or before) GetSunrise. If the calculation can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does not set, a null will be returned. See detailed explanation on top of the page.

summary> A utility method to return the time of an offset by degrees below or above the horizon of sunset. /summary> param name = "offsetZenith"> the degrees after GetSunset to use in the calculation. For time before sunset use negative numbers.

returns> The

See also:: DateTime

of the offset after (or before) GetSunset. If the calculation can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does not set, Double.NaN will be returned. See detailed explanation on top of the page.

virtual double Zmanim.AstronomicalCalendar.GetSunriseSolarDipFromOffset ( double minutes ) [virtual]

Will return the dip below the horizon before sunrise that matches the offset minutes on passed in. For example passing in 72 minutes for a calendar set to the equinox in Jerusalem returns a value close to 16.1° Please note that this method is very slow and inefficient and should NEVER be used in a loop. TODO: Improve efficiency.

Parameters:

minutes

offset

Returns:: the degrees below the horizon that match the offset on the equinox in Jerusalem at sea level.

See also:: GetSunsetSolarDipFromOffset

virtual DateTime Zmanim.AstronomicalCalendar.GetSunset ( ) [virtual]

The getSunset method Returns a DateTime representing the sunset time. The zenith used for the calculation uses geometric zenith of 90°. This is adjusted by the AstronomicalCalculator that adds approximately 50/60 of a degree to account for 34 archminutes of refraction and 16 archminutes for the sun's radius for a total of 90.83333°. See documentation for the specific implementation of the AstronomicalCalculator that you are using. Note: In certain cases the calculates sunset will occur before sunrise. This will typically happen when a timezone other than the local timezone is used (calculating Los Angeles sunset using a GMT timezone for example). In this case the sunset date will be incremented to the following date.

Returns:: the DateTime representing the exact sunset time. If the calculation can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does not set, a null will be returned. See detailed explanation on top of the page.

See also:: Calculator.AstronomicalCalculator.AdjustZenith

Implements Zmanim.IAstronomicalCalendar.

virtual double Zmanim.AstronomicalCalendar.GetSunsetSolarDipFromOffset ( double minutes ) [virtual]

Will return the dip below the horizon after sunset that matches the offset minutes on passed in. For example passing in 72 minutes for a calendar set to the equinox in Jerusalem returns a value close to 16.1° Please note that this method is very slow and inefficient and should NEVER be used in a loop. TODO: Improve efficiency.

Parameters:

minutes

offset

Returns:: the degrees below the horizon that match the offset on the equinox in Jerusalem at sea level.

See also:: GetSunriseSolarDipFromOffset

returns> an XML formatted representation of the class. It returns the default output of the toXML method.

seealso cref = "ZmanimFormatter.ToXml" />

virtual DateTime Zmanim.AstronomicalCalendar.GetSunTransit ( ) [virtual]

summary> A method that returns a DateTime from the time passed in /summary> param name = "time"> The time to be set as the time for the DateTime. The time expected is in the format: 18.75 for 6:45:00 PM

returns> The Date.

virtual long Zmanim.AstronomicalCalendar.GetTemporalHour	(	DateTime?	sunrise,
		DateTime?	sunset
	)			`[protected, virtual]`

summary> A method that returns sundial or solar noon. It occurs when the Sun is transitting the celestial meridian. In this class it is calculated as halfway between sunrise and sunset, which can be slightly off the real transit time due to the lengthening or shortening day. /summary> returns> the DateTime representing Sun's transit. If the calculation can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does not set, a null will be returned. See detailed explanation on top of the page.

virtual long Zmanim.AstronomicalCalendar.GetTemporalHour	(	DateTime	sunrise,
		DateTime	sunset
	)			`[virtual]`

Utility method that will allow the calculation of a temporal (solar) hour based on the sunrise and sunset passed to this method.

Parameters:

	sunrise	The start of the day.
	sunset	The end of the day.

Returns:

the

long

millisecond length of the temporal hour. If the calculation can't be computed (see explanation on top of the page) long.MinValue will be returned.

See also:: GetTemporalHour()

virtual long Zmanim.AstronomicalCalendar.GetTemporalHour ( ) [virtual]

Method to return a temporal (solar) hour. The day from sunrise to sunset is split into 12 equal parts with each one being a temporal hour.

Returns:: the long millisecond length of a temporal hour. If the calculation can't be computed (see explanation on top of the page) long.MinValue will be returned.

virtual DateTime Zmanim.AstronomicalCalendar.GetTimeOffset	(	DateTime	time,
		long	offset
	)			`[virtual]`

A utility method to return a date offset by the offset time passed in.

Parameters:

	time	the start time
	offset	the offset in milliseconds to add to the time.

Returns:: the DateTime with the offset in milliseconds added to it

virtual DateTime Zmanim.AstronomicalCalendar.GetTimeOffset	(	DateTime	time,
		double	offset
	)			`[virtual]`

Utility method that returns a date offset by the offset time passed in. This method casts the offset as a

long

and calls GetTimeOffset(System.DateTime,long).

Parameters:

	time	the start time
	offset	the offset in milliseconds to add to the time

Returns:: the DateTimewith the offset added to it

virtual double Zmanim.AstronomicalCalendar.GetUtcSeaLevelSunrise ( double zenith ) [virtual]

Method that returns the sunrise in UTC time without correction for time zone offset from GMT and without using daylight savings time. Non-sunrise and sunset calculations such as dawn and dusk, depend on the amount of visible light, something that is not affected by elevation. This method returns UTC sunrise calculated at sea level. This forms the base for dawn calculations that are calculated as a dip below the horizon before sunrise.

Parameters:

zenith

the degrees below the horizon. For time after sunrise use negative numbers.

Returns:: The time in the format: 18.75 for 18:45:00 UTC/GMT. If the calculation can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does not set, Double.NaN will be returned. See detailed explanation on top of the page.

See also:: GetUtcSunrise, GetUtcSeaLevelSunset

virtual double Zmanim.AstronomicalCalendar.GetUtcSeaLevelSunset ( double zenith ) [virtual]

Method that returns the sunset in UTC time without correction for elevation, time zone offset from GMT and without using daylight savings time. Non-sunrise and sunset calculations such as dawn and dusk, depend on the amount of visible light, something that is not affected by elevation. This method returns UTC sunset calculated at sea level. This forms the base for dusk calculations that are calculated as a dip below the horizon after sunset.

Parameters:

zenith

the degrees below the horizon. For time before sunset use negative numbers.

Returns:: The time in the format: 18.75 for 18:45:00 UTC/GMT. If the calculation can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does not set, Double.NaN will be returned. See detailed explanation on top of the page.

See also:: GetUtcSunset, GetUtcSeaLevelSunrise

summary> A method that adds time zone offset and daylight savings time to the raw UTC time. /summary> param name = "time"> The UTC time to be adjusted.

returns> The time adjusted for the time zone offset and daylight savings time.

virtual double Zmanim.AstronomicalCalendar.GetUtcSunrise ( double zenith ) [virtual]

Method that returns the sunrise in UTC time without correction for time zone offset from GMT and without using daylight savings time.

Parameters:

zenith

the degrees below the horizon. For time after sunrise use negative numbers.

Returns:: The time in the format: 18.75 for 18:45:00 UTC/GMT. If the calculation can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does not set, Double.NaN will be returned. See detailed explanation on top of the page.

virtual double Zmanim.AstronomicalCalendar.GetUtcSunset ( double zenith ) [virtual]

Method that returns the sunset in UTC time without correction for time zone offset from GMT and without using daylight savings time.

Parameters:

zenith

the degrees below the horizon. For time after before sunset use negative numbers.

Returns:: The time in the format: 18.75 for 18:45:00 UTC/GMT. If the calculation can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does not set, Double.NaN will be returned. See detailed explanation on top of the page.