### PVECT

Draw proper motion vectors

#### Description:

Draw proper motion vectors on a projection of the celestial sphere. The XCOL and YCOL data areas are assumed to contain positions in radians, the EXCOL and EYCOL data areas are assumed to contain the proper motions in radians per year. It is possible to use the ERSCALE parameter to multiply the the proper motion so that it is correct for a given number of years. (The proper motion in RA is assumed to be $\stackrel{̇}{\alpha }cos\delta$.)

pvect [erscale]

#### Parameters:

##### ERSCALE = _REAL (Read and Write)
The scale factor for multiplying the vectors.

[The value of the global parameter PONGO_ERSCALE is used. If PONGO_ERSCALE is not defined, the default value 1.0 is used.]

If TRUE, the ZCOL values are additionally used to multiply the vectors. [FALSE]
The geometry used to plot the data. 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.
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.
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.