B.1.5 CoordsDegrees

Functions for angle transformations and manipulations, with angles generally in degrees. In particular, methods for translating between degrees and HH:MM:SS.S or DDD:MM:SS.S type sexagesimal representations are provided.

degreesToDms( deg )

Converts an angle in degrees to a formatted degrees:minutes:seconds string. No fractional part of the seconds field is given.

• Parameters:
  • deg (floating point): angle in degrees
• Return value
  • (String): DMS-format string representing deg

degreesToDms( deg, secFig )

Converts an angle in degrees to a formatted degrees:minutes:seconds string with a given number of decimal places in the seconds field.

• Parameters:
  • deg (floating point): angle in degrees
  • secFig (integer): number of decimal places in the seconds field
• Return value
  • (String): DMS-format string representing deg

degreesToHms( deg )

Converts an angle in degrees to a formatted hours:minutes:seconds string. No fractional part of the seconds field is given.

• Parameters:
  • deg (floating point): angle in degrees
• Return value
  • (String): HMS-format string representing deg

degreesToHms( deg, secFig )

Converts an angle in degrees to a formatted hours:minutes:seconds string with a given number of decimal places in the seconds field.

• Parameters:
  • deg (floating point): angle in degrees
  • secFig (integer): number of decimal places in the seconds field
• Return value
  • (String): HMS-format string representing deg

dmsToDegrees( dms )

Converts a formatted degrees:minutes:seconds string to an angle in degrees. Delimiters may be colon, space, characters dm[s], or some others. Additional spaces and leading +/- are permitted. The :seconds part is optional.

• Parameters:
  • dms (String): formatted DMS string
• Return value
  • (floating point): angle in degrees specified by dms

hmsToDegrees( hms )

Converts a formatted hours:minutes:seconds string to an angle in degrees. Delimiters may be colon, space, characters hm[s], or some others. Additional spaces and leading +/- are permitted. The :seconds part is optional.

• Parameters:
  • hms (String): formatted HMS string
• Return value
  • (floating point): angle in degrees specified by hms

dmsToDegrees( deg, min, sec )

Converts degrees, minutes, seconds to an angle in degrees.

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 (floating point): degrees part of angle
  • min (floating point): minutes part of angle
  • sec (floating point): seconds part of angle
• Return value
  • (floating point): specified angle in degrees

hmsToDegrees( hour, min, sec )

Converts hours, minutes, seconds to an angle in degrees.

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 (floating point): degrees part of angle
  • min (floating point): minutes part of angle
  • sec (floating point): seconds part of angle
• Return value
  • (floating point): specified angle in degrees

skyDistanceDegrees( ra1, dec1, ra2, dec2 )

Calculates the separation (distance around a great circle) of two points on the sky in degrees.

• Parameters:
  • ra1 (floating point): right ascension of point 1 in degrees
  • dec1 (floating point): declination of point 1 in degrees
  • ra2 (floating point): right ascension of point 2 in degrees
  • dec2 (floating point): declination of point 2 in degrees
• Return value
  • (floating point): angular distance between point 1 and point 2 in degrees

posAngDegrees( ra1, dec1, ra2, dec2 )

Calculates the position angle between two points on the sky in degrees. The result is in the range +/-180. If point 2 is due east of point 1, the result is +90. Zero is returned if the points are coincident.

• Parameters:
  • ra1 (floating point): right ascension of point 1 in degrees
  • dec1 (floating point): declination of point 1 in degrees
  • ra2 (floating point): right ascension of point 2 in degrees
  • dec2 (floating point): declination of point 2 in degrees
• Return value
  • (floating point): bearing in degrees of point 2 from point 1.

polarDistanceDegrees( ra1, dec1, radius1, ra2, dec2, radius2 )

Calculates the distance in three dimensional space between two points specified in spherical polar coordinates.

• Parameters:
  • ra1 (floating point): right ascension of point 1 in degrees
  • dec1 (floating point): declination of point1 in degrees
  • radius1 (floating point): distance from origin of point1
  • ra2 (floating point): right ascension of point 2 in degrees
  • dec2 (floating point): declination of point2 in degrees
  • radius2 (floating point): distance from origin of point2
• Return value
  • (floating point): the linear distance between point1 and point2; units are as for radius1 and radius2