net.aerith.misao.util
Class Astro

java.lang.Object
  |
  +--net.aerith.misao.util.Astro

public class Astro

extends java.lang.Object

The Astro is a class which consists of constant values and static methods related to astronomy.

Field Summary

static double	BESSELL_1900 The Julian Day of B1900.0.
static double	BESSELL_1950 The Julian Day of B1950.0.
static double	EPSILON_1950 The ecliptic obliquity at 1950.0.
static double	EPSILON_2000 The ecliptic obliquity at 2000.0.
static double	GAUSSIAN_CONSTANT The Gaussian constant.
static double	JULIUS_1850 The Julian Day of J1850.0.
static double	JULIUS_1900 The Julian Day of J1900.0.
static double	JULIUS_2000 The Julian Day of J2000.0.
static double	LIGHT_TIME The light time in second.
static double	MAG_STEP The brightness ratio of 1 mag.
private static int[][]	p_b The parameters to calculate solar latitude.
private static long[][]	p_lr The parameters to calculate solar longitude.
static double	RAD The converter to radian unit (pi / 180).
static double	SBIG_RATIO The width to height ratio of SBIG ST-4/ST-6 images.

Constructor Summary

Astro()

Method Summary

static double	blendMagnitude(double mag1, double mag2) Blends the specified two magnitude.
static double	cosh(double x) Calculates cosh(x).
static double	epsilon2000(double t) Gets the ecliptic inclination in J2000.0.
static double	get_t1850(double jd) Gets the T1850.
static double	get_t1900(double jd) Gets the T1900.
static double	get_t2000(double jd) Gets the T2000.
static double	getDistanceOfAngles(double angle1, double angle2) Gets the distance between the specified two angles.
static double	getMeanAngle(double angle1, double angle2) Gets the mean value the specified two angles.
static double	getMeanAngle(double angle1, double angle2, double weight1, double weight2) Gets the mean value the specified two angles, considering the specified weights.
static double	getProperLimitingMagnitude(double pixel_size) Gets the proper limiting magnitude to plot on chart, based on the pixel size.
static Xyz	getSolarCoordinates(double jd) Gets the equatorial coordinates of the Sun.
static double	greenwich2000(double t) Gets the Greenwich sidereal time in J2000.0
static double	normalize(double value, double maximum) Normalize the specified value into the proper range.
static double	sinh(double x) Calculates sinh(x).

Methods inherited from class java.lang.Object

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

Field Detail

RAD

public static final double RAD

The converter to radian unit (pi / 180).

BESSELL_1900

public static final double BESSELL_1900

The Julian Day of B1900.0. Note that this is not exactly correct. This is actually J1900.0.

BESSELL_1950

public static final double BESSELL_1950

The Julian Day of B1950.0.

JULIUS_1850

public static final double JULIUS_1850

The Julian Day of J1850.0.

JULIUS_1900

public static final double JULIUS_1900

The Julian Day of J1900.0.

JULIUS_2000

public static final double JULIUS_2000

The Julian Day of J2000.0.

EPSILON_1950

public static final double EPSILON_1950

The ecliptic obliquity at 1950.0.

EPSILON_2000

public static final double EPSILON_2000

The ecliptic obliquity at 2000.0.

GAUSSIAN_CONSTANT

public static final double GAUSSIAN_CONSTANT

The Gaussian constant.

LIGHT_TIME

public static final double LIGHT_TIME

The light time in second.

SBIG_RATIO

public static final double SBIG_RATIO

The width to height ratio of SBIG ST-4/ST-6 images.

MAG_STEP

public static final double MAG_STEP

The brightness ratio of 1 mag.

p_lr

private static final long[][] p_lr

The parameters to calculate solar longitude.

p_b

private static final int[][] p_b

The parameters to calculate solar latitude.

Constructor Detail

Astro

public Astro()

Method Detail

normalize

public static double normalize(double value,
                               double maximum)

Normalize the specified value into the proper range.

Parameters:

value - the value.

maximum - the maximum value of range, which must be positive.

Returns:

the normalized value, which is between 0 and the specified maximum value.

sinh

public static final double sinh(double x)

Calculates sinh(x).

Parameters:

x - the argument.

Returns:

the sinh(x).

cosh

public static final double cosh(double x)

Calculates cosh(x).

Parameters:

x - the argument.

Returns:

the cosh(x).

get_t1850

public static double get_t1850(double jd)

Gets the T1850.

Parameters:

jd - the Julian day.

Returns:

the T1850.

get_t1900

public static double get_t1900(double jd)

Gets the T1900.

Parameters:

jd - the Julian day.

Returns:

the T1900.

get_t2000

public static double get_t2000(double jd)

Gets the T2000.

Parameters:

jd - the Julian day.

Returns:

the T2000.

epsilon2000

public static double epsilon2000(double t)

Gets the ecliptic inclination in J2000.0.

Parameters:

t - the T2000.

Returns:

the ecliptic inclination.

greenwich2000

public static double greenwich2000(double t)

Gets the Greenwich sidereal time in J2000.0

Parameters:

t - the T2000.

Returns:

the Greenwich sidereal time in J2000.0

getProperLimitingMagnitude

public static double getProperLimitingMagnitude(double pixel_size)

Gets the proper limiting magnitude to plot on chart, based on the pixel size.

This equation is determined so that the answer will satisfy the following table.

Pixel size (arcmin)	Ideal Lm.	Calculated Lm.
100	10.0	9.5
20	13.5	13.7
12	14.5	15.0
7.0	16.5	16.4
3.5	18.0	18.2
2.3	19.5	19.3
1.3	20.5	20.8

Parameters:

pixel_size - the pixel size in degree.

Returns:

the limiting magnitude.

blendMagnitude

public static double blendMagnitude(double mag1,
                                    double mag2)

Blends the specified two magnitude.

Parameters:

mag1 - the magnitude of first star.

mag2 - the magnitude of second star.

Returns:

the blended magnitude.

getDistanceOfAngles

public static double getDistanceOfAngles(double angle1,
                                         double angle2)

Gets the distance between the specified two angles.

Parameters:

angle1 - the angle.

angle2 - another angle.

Returns:

the distance between the specified two angles, which is between 0 and 180.

getMeanAngle

public static double getMeanAngle(double angle1,
                                  double angle2)

Gets the mean value the specified two angles.

Parameters:

angle1 - the angle.

angle2 - another angle.

Returns:

the mean value the specified two angles, which is between 0 and 360.

getMeanAngle

public static double getMeanAngle(double angle1,
                                  double angle2,
                                  double weight1,
                                  double weight2)

Gets the mean value the specified two angles, considering the specified weights.

Parameters:

angle1 - the angle.

angle2 - another angle.

weight1 - the weight of angle1.

weight2 - the weight of angle2.

Returns:

the mean value the specified two angles, which is between 0 and 360.

getSolarCoordinates

public static Xyz getSolarCoordinates(double jd)

Gets the equatorial coordinates of the Sun.

Parameters:

jd - the Julian Day.

Returns:

the equatorial coordinates of the Sun.