uk.ac.starlink.ttools.func

## Class CoordsRadians

• ```public class CoordsRadians
extends Object```
Functions for angle transformations and manipulations, based on radians rather than degrees. In particular, methods for translating between radians and HH:MM:SS.S or DDD:MM:SS.S type sexagesimal representations are provided.
Since:
30 Apr 2004
Author:
Mark Taylor (Starlink)
• ### Field Summary

Fields
Modifier and Type Field and Description
`static double` `ARC_MINUTE_RADIANS`
The size of one arcminute in radians.
`static double` `ARC_SECOND_RADIANS`
The size of one arcsecond in radians.
`static double` `DEGREE_RADIANS`
The size of one degree in radians.
`static double` `HOUR_RADIANS`
The size of one hour of right ascension in radians.
• ### Method Summary

All Methods
Modifier and Type Method and Description
`static double` ```decFK4toFK5radians(double raFK4, double decFK4)```
Converts a B1950.0 FK4 position to J2000.0 FK5 at an epoch of B1950.0 yielding Declination This assumes zero proper motion in the FK5 frame.
`static double` ```decFK4toFK5Radians(double raFK4, double decFK4, double bepoch)```
Converts a B1950.0 FK4 position to J2000.0 FK5 yielding Declination.
`static double` ```decFK5toFK4radians(double raFK5, double decFK5)```
Converts a J2000.0 FK5 position to B1950.0 FK4 at an epoch of B1950.0 yielding Declination.
`static double` ```decFK5toFK4Radians(double raFK5, double decFK5, double bepoch)```
Converts a J2000.0 FK5 position to B1950.0 FK4 yielding Declination.
`static double` `degreesToRadians(double deg)`
Converts degrees to radians.
`static double` ```dmsToRadians(double deg, double min, double sec)```
Converts degrees, minutes, seconds to an angle in radians.
`static double` `dmsToRadians(String dms)`
Converts a formatted degrees:minutes:seconds string to an angle in radians.
`static double` ```hmsToRadians(double hour, double min, double sec)```
Converts hours, minutes, seconds to an angle in radians.
`static double` `hmsToRadians(String hms)`
Converts a formatted hours:minutes:seconds string to an angle in radians.
`static double` `hoursToRadians(double hours)`
Converts hours to radians.
`static double` ```polarDistanceRadians(double ra1, double dec1, double radius1, double ra2, double dec2, double radius2)```
Calculates the distance in three dimensional space between two points specified in spherical polar coordinates.
`static double` ```posAngRadians(double ra1, double dec1, double ra2, double dec2)```
Calculates the position angle between two points on the sky in radians.
`static double` `radiansToDegrees(double rad)`
Converts radians to degrees.
`static String` `radiansToDms(double rad)`
Converts an angle in radians to a formatted degrees:minutes:seconds string.
`static String` ```radiansToDms(double rad, int secFig)```
Converts an angle in radians to a formatted degrees:minutes:seconds string with a given number of decimal places in the seconds field.
`static String` `radiansToHms(double rad)`
Converts an angle in radians to a formatted hours:minutes:seconds string.
`static String` ```radiansToHms(double rad, int secFig)```
Converts an angle in radians to a formatted hours:minutes:seconds string with a given number of decimal places in the seconds field.
`static double` ```raFK4toFK5radians(double raFK4, double decFK4)```
Converts a B1950.0 FK4 position to J2000.0 FK5 at an epoch of B1950.0 yielding Right Ascension.
`static double` ```raFK4toFK5Radians(double raFK4, double decFK4, double bepoch)```
Converts a B1950.0 FK4 position to J2000.0 FK5 yielding Right Ascension.
`static double` ```raFK5toFK4radians(double raFK5, double decFK5)```
Converts a J2000.0 FK5 position to B1950.0 FK4 at an epoch of B1950.0 yielding Declination.
`static double` ```raFK5toFK4Radians(double raFK5, double decFK5, double bepoch)```
Converts a J2000.0 FK5 position to B1950.0 FK4 yielding Declination.
`static double` ```skyDistanceRadians(double ra1, double dec1, double ra2, double dec2)```
Calculates the separation (distance around a great circle) of two points on the sky in radians.
• ### Methods inherited from class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`
• ### Field Detail

• #### DEGREE_RADIANS

`public static final double DEGREE_RADIANS`
The size of one degree in radians.
See Also:
Constant Field Values
• #### HOUR_RADIANS

`public static final double HOUR_RADIANS`
The size of one hour of right ascension in radians.
See Also:
Constant Field Values
• #### ARC_MINUTE_RADIANS

`public static final double ARC_MINUTE_RADIANS`
The size of one arcminute in radians.
See Also:
Constant Field Values
• #### ARC_SECOND_RADIANS

`public static final double ARC_SECOND_RADIANS`
The size of one arcsecond in radians.
See Also:
Constant Field Values
• ### Method Detail

• #### radiansToDms

`public static String radiansToDms(double rad)`
Converts an angle in radians to a formatted degrees:minutes:seconds string. No fractional part of the seconds field is given.
Parameters:
`rad` - angle in radians
Returns:
DMS-format string representing `rad`
• #### radiansToDms

```public static String radiansToDms(double rad,
int secFig)```
Converts an angle in radians to a formatted degrees:minutes:seconds string with a given number of decimal places in the seconds field.
Parameters:
`rad` - angle in radians
`secFig` - number of decimal places in the seconds field
Returns:
DMS-format string representing `rad`
• #### radiansToHms

`public static String radiansToHms(double rad)`
Converts an angle in radians to a formatted hours:minutes:seconds string. No fractional part of the seconds field is given.
Parameters:
`rad` - angle in radians
Returns:
HMS-format string representing `rad`
• #### radiansToHms

```public static String radiansToHms(double rad,
int secFig)```
Converts an angle in radians to a formatted hours:minutes:seconds string with a given number of decimal places in the seconds field.
Parameters:
`rad` - angle in radians
`secFig` - number of decimal places in the seconds field
Returns:
HMS-format string representing `rad`
• #### dmsToRadians

`public static double dmsToRadians(String dms)`
Converts a formatted degrees:minutes:seconds string to an angle in radians. Delimiters may be colon, space, characters `dm[s]`, or some others. Additional spaces and leading +/- are permitted. The :seconds part is optional.
Parameters:
`dms` - formatted DMS string
Returns:
angle in radians specified by `dms`
Throws:
`NumberFormatException` - if `dms` can't be parsed as a degrees:minutes:seconds string
• #### hmsToRadians

`public static double hmsToRadians(String hms)`
Converts a formatted hours:minutes:seconds string to an angle in radians. Delimiters may be colon, space, characters `hm[s]`, or some others. Additional spaces and leading +/- are permitted. The :seconds part is optional.
Parameters:
`hms` - formatted HMS string
Returns:
angle in radians specified by `hms`
Throws:
`NumberFormatException` - if `dms` can't be parsed as an hours:minutes:seconds string
• #### dmsToRadians

```public static double dmsToRadians(double deg,
double min,
double sec)```
Converts degrees, minutes, seconds to an angle in radians.

In conversions of this type, one has to be careful to get the sign right in converting angles which are between 0 and -1 degrees. This routine uses the sign bit of the `deg` argument, taking care to distinguish between +0 and -0 (their internal representations are different for floating point values). It is illegal for the `min` or `sec` arguments to be negative.

Parameters:
`deg` - degrees part of angle
`min` - minutes part of angle
`sec` - seconds part of angle
Returns:
specified angle in radians
Throws:
`IllegalArgumentException` - if an argument after the first non-zero one is negative
• #### hmsToRadians

```public static double hmsToRadians(double hour,
double min,
double sec)```
Converts hours, minutes, seconds to an angle in radians.

In conversions of this type, one has to be careful to get the sign right in converting angles which are between 0 and -1 hours. This routine uses the sign bit of the `hour` argument, taking care to distinguish between +0 and -0 (their internal representations are different for floating point values).

Parameters:
`hour` - degrees part of angle
`min` - minutes part of angle
`sec` - seconds part of angle
Returns:
specified angle in radians
Throws:
`IllegalArgumentException` - if an argument after the first non-zero one is negative
• #### skyDistanceRadians

```public static double skyDistanceRadians(double ra1,
double dec1,
double ra2,
double dec2)```
Calculates the separation (distance around a great circle) of two points on the sky in radians.
Parameters:
`ra1` - right ascension of point 1 in radians
`dec1` - declination of point 1 in radians
`ra2` - right ascension of point 2 in radians
`dec2` - declination of point 2 in radians
Returns:
angular distance between point 1 and point 2 in radians
• #### posAngRadians

```public static double posAngRadians(double ra1,
double dec1,
double ra2,
double dec2)```
Calculates the position angle between two points on the sky in radians. The result is in the range +/-pi. If point 2 is due east of point 1, the result is +pi/2. Zero is returned if the points are coincident.
Parameters:
`ra1` - right ascension of point 1 in radians
`dec1` - declination of point 1 in radians
`ra2` - right ascension of point 2 in radians
`dec2` - declination of point 2 in radians
Returns:
bearing in radians of point 2 from point 1
• #### polarDistanceRadians

```public static double polarDistanceRadians(double ra1,
double dec1,
double radius1,
double ra2,
double dec2,
double radius2)```
Calculates the distance in three dimensional space between two points specified in spherical polar coordinates.
Parameters:
`ra1` - right ascension of point 1 in radians
`dec1` - declination of point1 in radians
`radius1` - distance from origin of point1
`ra2` - right ascension of point 2 in radians
`dec2` - declination of point2 in radians
`radius2` - distance from origin of point2
Returns:
the linear distance between point1 and point2; units are as for `radius1` and `radius2`
• #### hoursToRadians

`public static double hoursToRadians(double hours)`
Converts hours to radians.
Parameters:
`hours` - angle in hours
Returns:
angle in radians
• #### degreesToRadians

`public static double degreesToRadians(double deg)`
Converts degrees to radians.
Parameters:
`deg` - angle in degrees
Returns:
angle in radians
• #### radiansToDegrees

`public static double radiansToDegrees(double rad)`
Converts radians to degrees.
Parameters:
`rad` - angle in radians
Returns:
angle in degrees
• #### raFK4toFK5radians

```public static double raFK4toFK5radians(double raFK4,
double decFK4)```
Converts a B1950.0 FK4 position to J2000.0 FK5 at an epoch of B1950.0 yielding Right Ascension. This assumes zero proper motion in the FK5 frame.
Parameters:
`raFK4` - right ascension in B1950.0 FK4 system (radians)
`decFK4` - declination in B1950.0 FK4 system (radians)
Returns:
right ascension in J2000.0 FK5 system (radians)
See Also:
`Pal.Fk45z(uk.ac.starlink.pal.AngleDR, double)`
• #### decFK4toFK5radians

```public static double decFK4toFK5radians(double raFK4,
double decFK4)```
Converts a B1950.0 FK4 position to J2000.0 FK5 at an epoch of B1950.0 yielding Declination This assumes zero proper motion in the FK5 frame.
Parameters:
`raFK4` - right ascension in B1950.0 FK4 system (radians)
`decFK4` - declination in B1950.0 FK4 system (radians)
Returns:
declination in J2000.0 FK5 system (radians)
See Also:
`Pal.Fk45z(uk.ac.starlink.pal.AngleDR, double)`
• #### raFK5toFK4radians

```public static double raFK5toFK4radians(double raFK5,
double decFK5)```
Converts a J2000.0 FK5 position to B1950.0 FK4 at an epoch of B1950.0 yielding Declination. This assumes zero proper motion, parallax and radial velocity in the FK5 frame.
Parameters:
`raFK5` - right ascension in J2000.0 FK5 system (radians)
`decFK5` - declination in J2000.0 FK5 system (radians)
Returns:
right ascension in the FK4 system (radians)
See Also:
`Pal.Fk54z(uk.ac.starlink.pal.AngleDR, double)`
• #### decFK5toFK4radians

```public static double decFK5toFK4radians(double raFK5,
double decFK5)```
Converts a J2000.0 FK5 position to B1950.0 FK4 at an epoch of B1950.0 yielding Declination. This assumes zero proper motion, parallax and radial velocity in the FK5 frame.
Parameters:
`raFK5` - right ascension in J2000.0 FK5 system (radians)
`decFK5` - declination in J2000.0 FK5 system (radians)
Returns:
right ascension in the FK4 system (radians)
See Also:
`Pal.Fk54z(uk.ac.starlink.pal.AngleDR, double)`
• #### raFK4toFK5Radians

```public static double raFK4toFK5Radians(double raFK4,
double decFK4,
double bepoch)```
Converts a B1950.0 FK4 position to J2000.0 FK5 yielding Right Ascension. This assumes zero proper motion in the FK5 frame. The `bepoch` parameter is the epoch at which the position in the FK4 frame was determined.
Parameters:
`raFK4` - right ascension in B1950.0 FK4 system (radians)
`decFK4` - declination in B1950.0 FK4 system (radians)
`bepoch` - Besselian epoch
Returns:
right ascension in J2000.0 FK5 system (radians)
See Also:
`Pal.Fk45z(uk.ac.starlink.pal.AngleDR, double)`
• #### decFK4toFK5Radians

```public static double decFK4toFK5Radians(double raFK4,
double decFK4,
double bepoch)```
Converts a B1950.0 FK4 position to J2000.0 FK5 yielding Declination. This assumes zero proper motion in the FK5 frame. The `bepoch` parameter is the epoch at which the position in the FK4 frame was determined.
Parameters:
`raFK4` - right ascension in B1950.0 FK4 system (radians)
`decFK4` - declination in B1950.0 FK4 system (radians)
`bepoch` - Besselian epoch
Returns:
declination in J2000.0 FK5 system (radians)
See Also:
`Pal.Fk45z(uk.ac.starlink.pal.AngleDR, double)`
• #### raFK5toFK4Radians

```public static double raFK5toFK4Radians(double raFK5,
double decFK5,
double bepoch)```
Converts a J2000.0 FK5 position to B1950.0 FK4 yielding Declination. This assumes zero proper motion, parallax and radial velocity in the FK5 frame.
Parameters:
`raFK5` - right ascension in J2000.0 FK5 system (radians)
`decFK5` - declination in J2000.0 FK5 system (radians)
`bepoch` - Besselian epoch
Returns:
right ascension in the FK4 system (radians)
See Also:
`Pal.Fk54z(uk.ac.starlink.pal.AngleDR, double)`
• #### decFK5toFK4Radians

```public static double decFK5toFK4Radians(double raFK5,
double decFK5,
double bepoch)```
Converts a J2000.0 FK5 position to B1950.0 FK4 yielding Declination. This assumes zero proper motion, parallax and radial velocity in the FK5 frame.
Parameters:
`raFK5` - right ascension in J2000.0 FK5 system (radians)
`decFK5` - declination in J2000.0 FK5 system (radians)
`bepoch` - Besselian epoch
Returns:
right ascension in the FK4 system (radians)
See Also:
`Pal.Fk54z(uk.ac.starlink.pal.AngleDR, double)`

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