astro

Class Broker

java.lang.Object

astro.Broker

public class Broker
extends Object

A stand-alone code excerpt for static telescope brokerage. This class allows decision of targets being observable at a given location. At the date in question, this includes that

• The object is at least minheight above the horizon.
• The sun is at least sunheight below the horizon.

The accuracy of the alogirthm is not too high and is estimated to give the sun's position down to a quarter of a degree around the year of 2000.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Broker.Height Test the height of an astronomical object.
static class	Broker.Sol Test the solar height.

Field Summary

Fields

Modifier and Type	Field and Description
private static double	A1EQC The constant coefficient in equation of center of the sun.
private static double	A2EQC The constant coefficient in equation of center of the sun.
private static double	A3EQC The linear coefficient in equation of center of the sun.
private static double	ALAM The constant coefficient in apparent longitude.
private static double	AM The constant coefficient in geometric mean longitude.
private static double	ANU Constant coefficient for calculating mean perihelium.
private static double	ANULL The constant coefficient in geometric mean anomaly.
private static double	ASUN The constant coefficient, ecliptic obliquity.
private static double	B1EQC The linear coefficient in equation of center of the sun.
private static double	B2EQC The linear coefficient in equation of center of the sun.
private static double	BLAM The linear coefficient in apparent longitude.
private static double	BM The linear coefficient in geometric mean longitude.
private static double	BNU Linear coefficient for calculating mean perihelium.
private static double	BNULL The linear coefficient in geometric mean anomaly.
private static double	BSUN The linear coefficient, ecliptic obliquity.
private static double	C1EQC The quadratic coefficient in equation of center of the sun.
private static double	CM The quadratic coefficient in geometric mean longitude.
private static double	CNULL The quadratic coefficient in geometric mean anomaly.
private static double[]	CONST Constants required for the siderael time algorithm.
static double	DEFAULTHEIGHT Default minimum object height.
static double	DEFAULTSOL Default maximum solar height.
private static DateFormat	ISODATE The ISO-date formatter

Constructor Summary

Constructors

Constructor and Description
Broker()

Method Summary

Modifier and Type	Method and Description
static double	getEclipticObliquity(Date time) Calculates the obliquity of the ecliptic in degrees.
static double	getHeight(Date time, double ra, double de, double longitude, double latitude) Calculates the height above the horizon for a given astronomical object at a certain site, for time time.
static double	getJd(Date time) Gets the julian date from a date object.
static double	getJulianCentury(Date time) Calculates the julian centruries since 2000.0 from a date object.
static double	getSidereal(Date time, double longitude) Calculates the apparent sidereal time for a given time and longitude in degrees.
static double	getSolLambda(Date time) Calculates the solar apparent ecliptic longitude in degrees.
static double	getSunHeight(Date time, double longitude, double latitude) Returns the solar hight for a given time and a certain location.
static boolean	isObservable(Date time, double longitude, double latitude, double ra, double de) Returns true, if the given target is currently observable at this location.
static boolean	isObservable(Date time, double longitude, double latitude, double ra, double de, double maxsol) Returns true, if the given target is currently observable at this location.
static boolean	isObservable(Date time, double longitude, double latitude, double ra, double de, double minheight, double maxsol) Returns true, if the given target is currently observable at this location.
static boolean	isObservable(double longitude, double latitude, double ra, double de) If the time of the observation is unknown, we can deduce if the target might be visible at all.
static boolean	isObservable(double longitude, double latitude, double ra, double de, double minheight) If the time of the observation is unknown, we can deduce if the target might be visible at all.

Methods inherited from class java.lang.Object

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

Field Detail

ANULL

private static final double ANULL

The constant coefficient in geometric mean anomaly.

See Also:

Constant Field Values

BNULL

private static final double BNULL

The linear coefficient in geometric mean anomaly.

See Also:

Constant Field Values

CNULL

private static final double CNULL

The quadratic coefficient in geometric mean anomaly.

See Also:

Constant Field Values

AM

private static final double AM

The constant coefficient in geometric mean longitude.

See Also:

Constant Field Values

BM

private static final double BM

The linear coefficient in geometric mean longitude.

See Also:

Constant Field Values

CM

private static final double CM

The quadratic coefficient in geometric mean longitude.

See Also:

Constant Field Values

A1EQC

private static final double A1EQC

The constant coefficient in equation of center of the sun.

See Also:

Constant Field Values

B1EQC

private static final double B1EQC

The linear coefficient in equation of center of the sun.

See Also:

Constant Field Values

C1EQC

private static final double C1EQC

The quadratic coefficient in equation of center of the sun.

See Also:

Constant Field Values

A2EQC

private static final double A2EQC

The constant coefficient in equation of center of the sun.

See Also:

Constant Field Values

B2EQC

private static final double B2EQC

The linear coefficient in equation of center of the sun.

See Also:

Constant Field Values

A3EQC

private static final double A3EQC

The linear coefficient in equation of center of the sun.

See Also:

Constant Field Values

ALAM

private static final double ALAM

The constant coefficient in apparent longitude.

See Also:

Constant Field Values

BLAM

private static final double BLAM

The linear coefficient in apparent longitude.

See Also:

Constant Field Values

ANU

private static final double ANU

Constant coefficient for calculating mean perihelium.

See Also:

Constant Field Values

BNU

private static final double BNU

Linear coefficient for calculating mean perihelium.

See Also:

Constant Field Values

ASUN

private static final double ASUN

The constant coefficient, ecliptic obliquity.

See Also:

Constant Field Values

BSUN

private static final double BSUN

The linear coefficient, ecliptic obliquity.

See Also:

Constant Field Values

CONST

private static final double[] CONST

Constants required for the siderael time algorithm.

DEFAULTSOL

public static final double DEFAULTSOL

Default maximum solar height.

See Also:

Constant Field Values

DEFAULTHEIGHT

public static final double DEFAULTHEIGHT

Default minimum object height.

See Also:

Constant Field Values

ISODATE

private static final DateFormat ISODATE

The ISO-date formatter

Constructor Detail

Broker

public Broker()

Method Detail

getJd

public static double getJd(Date time)

Gets the julian date from a date object.

Parameters:

time - Date of observation.

Returns:

The JD correponding to the date object.

getJulianCentury

public static double getJulianCentury(Date time)

Calculates the julian centruries since 2000.0 from a date object.

Parameters:

time - Date of observation.

Returns:

The passed julian centuries since 2000.0.

getSidereal

public static double getSidereal(Date time,
                                 double longitude)

Calculates the apparent sidereal time for a given time and longitude in degrees. Approximate formular.

Parameters:

time - Date of observation.

longitude - Geographical longirude in degrees, W is negative.

Returns:

The local apparent sidereal time in degrees.

getSolLambda

public static double getSolLambda(Date time)

Calculates the solar apparent ecliptic longitude in degrees. Refer to NOAA solar position calculator.

Parameters:

time - Date of observation.

Returns:

Apparent ecliptical longitude of the Sun in degrees.

getEclipticObliquity

public static double getEclipticObliquity(Date time)

Calculates the obliquity of the ecliptic in degrees. Refer to NOAA solar position calculator.

Parameters:

time - Date of observation.

Returns:

Ecliptic Obliquity in degrees.

getSunHeight

public static double getSunHeight(Date time,
                                  double longitude,
                                  double latitude)

Returns the solar hight for a given time and a certain location. Calculates right ascension and declination of sun and get's this object's height via getHeight(java.util.Date, double, double, double, double).

Parameters:

time - Date of the observation as a Java Date object.

longitude - Longitude of site, in degrees, W negativ.

latitude - Latitude of site, in degrees.

getHeight

public static double getHeight(Date time,
                               double ra,
                               double de,
                               double longitude,
                               double latitude)

Calculates the height above the horizon for a given astronomical object at a certain site, for time time. The right ascension and declination of the object are apparent right ascension and declination of the object, both in degrees. The telescope's location is defined by its longitude and latitude, both in degrees. Longitude is negative for Western longitudes.
Does not include refraction or aberration.

Parameters:

time - Date of the observation as a Java Date object.

ra - Right ascension of object, degrees.

de - Declination of object, degrees.

longitude - Longitude of site, in degrees, W negativ.

latitude - Latitude of site, in degrees.

isObservable

public static boolean isObservable(double longitude,
                                   double latitude,
                                   double ra,
                                   double de)

If the time of the observation is unknown, we can deduce if the target might be visible at all. Note: Longitude and ra are not used.

Parameters:

ra - Right ascension of object, degrees.

de - Declination of object, degrees.

longitude - Longitude of site, in degrees, W negativ.

latitude - Latitude of site, in degrees.

isObservable

public static boolean isObservable(double longitude,
                                   double latitude,
                                   double ra,
                                   double de,
                                   double minheight)

If the time of the observation is unknown, we can deduce if the target might be visible at all. Note: Longitude and ra are not used.

Parameters:

ra - Right ascension of object, degrees.

de - Declination of object, degrees.

longitude - Longitude of site, in degrees, W negativ.

latitude - Latitude of site, in degrees.

minheight - Star should be at least that high.

isObservable

public static boolean isObservable(Date time,
                                   double longitude,
                                   double latitude,
                                   double ra,
                                   double de)

Returns true, if the given target is currently observable at this location.

Parameters:

time - Date of the observation as a Java Date object.

ra - Right ascension of object, degrees.

de - Declination of object, degrees.

longitude - Longitude of site, in degrees, W negativ.

latitude - Latitude of site, in degrees.

isObservable

public static boolean isObservable(Date time,
                                   double longitude,
                                   double latitude,
                                   double ra,
                                   double de,
                                   double maxsol)

Returns true, if the given target is currently observable at this location.

Parameters:

time - Date of the observation as a Java Date object.

ra - Right ascension of object, degrees.

de - Declination of object, degrees.

longitude - Longitude of site, in degrees, W negativ.

latitude - Latitude of site, in degrees.

isObservable

public static boolean isObservable(Date time,
                                   double longitude,
                                   double latitude,
                                   double ra,
                                   double de,
                                   double minheight,
                                   double maxsol)

Returns true, if the given target is currently observable at this location.

Parameters:

time - Date of the observation as a Java Date object.

ra - Right ascension of object, degrees.

de - Declination of object, degrees.

longitude - Longitude of site, in degrees, W negativ.

latitude - Latitude of site, in degrees.

minheight - Star should be at least that high.

maxsol - Sun should be at least this low.