GT_CIRCLE

Draw a great circle between two points

Description:

Draw a great circle between two points in current projection. The great circle is specified by giving the coordinates in degrees of two points on the celestial sphere. Either the small or large great circle may be drawn.

Usage:

gt_circle [phistart] [thestart] [phiend] [theend]

Parameters:

PHISTART = _DOUBLE (Read and Write)
The longitude of the start of the great circle in degrees.

If no value is specified on the command line, the current value is used. The current value is initially set to 0.0.

THESTART = _DOUBLE (Read and Write)
The latitude of the start of the great circle in degrees.

If no value is specified on the command line, the current value is used. The current value is initially set to 0.0

PHIEND = _DOUBLE (Read and Write)
The longitude of the end of the great circle in degrees.

If no value is specified on the command line, the current value is used. The current value is initially set to 0.0.

THEEND = _DOUBLE (Read and Write)
The latitude of the end of the great circle in degrees.

If no value is specified on the command line, the current value is used. The current value is initially set to 0.0.

ACUTE = _LOGICAL (Read and Write)
If TRUE, the smaller great circle arc is drawn between the given points.

If no value is specified on the command line, the current value is used. The current value is initially set to TRUE.

PROJECTION = _CHAR (Read)
The geometry to be used to plot the great circle. This is explained in more detail in the section on projections. Allowed values: "NONE", "TAN", "SIN", "ARC", "GLS", "AITOFF", "MERCATOR" and "STG".

This parameter is not specified on the command line. The value of the global parameter PONGO_PROJECTN is used. If PONGO_PROJECTN is not defined, the default value "NONE" is used.

RACENTRE = _CHAR (Read)
The centre of the projection in RA (i.e. the angle must be specified as hh:mm:ss.sss). This parameter is only required for PROJECTION values other than "NONE".

This parameter is not specified on the command line. The value of the global parameter PONGO_RACENTRE is used. If PONGO_RACENTRE is not defined, the default value "0" is used.

DECCENTRE = _CHAR (Read)
The centre of the projection in declination (i.e. the angle must be specified as dd:mm:ss.sss). This parameter is only required for PROJECTION values other than "NONE".

This parameter is not specified on the command line. The value of the global parameter PONGO_DECCENTRE is used. If PONGO_DECCENTRE is not defined, the default value "0" is used.