Class JulianDate

java.lang.Object

org.episteme.natural.physics.astronomy.time.JulianDate

public class JulianDate
extends Object

Julian Date (JD) representation and conversions. Julian Date is a continuous count of days since the beginning of the Julian Period (January 1, 4713 BC, Julian calendar).

Since:

1.0

Author:

Silvere Martin-Michiellot, Gemini AI (Google DeepMind)

Field Summary

Fields

Modifier and Type	Field	Description
static final double	B1950	Julian Date for B1950.0 epoch
static final double	DAYS_PER_CENTURY	Days per Julian century
static final double	J2000	Julian Date for J2000.0 epoch (2000-01-01 12:00:00 TT)

Constructor Summary

Constructors

Constructor	Description
JulianDate(double julianDate)

Method Summary

Modifier and Type	Method	Description
JulianDate	addDays(double days)	Adds days to this Julian Date.
static JulianDate	fromGregorian(int year, int month, double day)	Creates a JulianDate from a Gregorian calendar date and time (UTC).
static JulianDate	fromLocalDateTime(LocalDateTime dateTime)	Creates a JulianDate from Java LocalDateTime (assumes UTC).
int	getDayOfWeek()	Returns the day of week (0 = Monday, 6 = Sunday).
double	getJulianCenturies()	Returns Julian centuries since J2000.0.
double	getModifiedJulianDate()	Returns Modified Julian Date (MJD = JD - 2400000.5).
double	getValue()
static JulianDate	now()	Returns current Julian Date.
double[]	toGregorian()	Converts back to Gregorian calendar.
String	toString()

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

J2000

public static final double J2000

Julian Date for J2000.0 epoch (2000-01-01 12:00:00 TT)

See Also:

• Constant Field Values

B1950

public static final double B1950

Julian Date for B1950.0 epoch

See Also:

• Constant Field Values

DAYS_PER_CENTURY

public static final double DAYS_PER_CENTURY

Days per Julian century

See Also:

• Constant Field Values

Constructor Details

JulianDate

public JulianDate(double julianDate)

Method Details

fromGregorian

public static JulianDate fromGregorian(int year,
 int month,
 double day)

Creates a JulianDate from a Gregorian calendar date and time (UTC).

Parameters:

year - Year (e.g., 2024)

month - Month (1-12)

day - Day of month (1-31, can include fractional days)

Returns:

JulianDate for the specified date/time

fromLocalDateTime

public static JulianDate fromLocalDateTime(LocalDateTime dateTime)

Creates a JulianDate from Java LocalDateTime (assumes UTC).

toGregorian

public double[] toGregorian()

Converts back to Gregorian calendar.

Returns:

Array [year, month, day] where day may be fractional

getJulianCenturies

public double getJulianCenturies()

Returns Julian centuries since J2000.0. T = (JD - 2451545.0) / 36525

getModifiedJulianDate

public double getModifiedJulianDate()

Returns Modified Julian Date (MJD = JD - 2400000.5). MJD starts at midnight, making it more convenient for modern use.

addDays

public JulianDate addDays(double days)

Adds days to this Julian Date.

getDayOfWeek

public int getDayOfWeek()

Returns the day of week (0 = Monday, 6 = Sunday).

getValue

public double getValue()

toString

public String toString()

Overrides:

toString in class Object

now

public static JulianDate now()

Returns current Julian Date.