The plotting frame is defined by the command FRAME. The frame may be in Equatorial coordinates (Righ Ascension-Declination) or in Horizontal coordinates (Azimuth-Elevation, as seen from the seleted observatory and at the time defined by the TIME command). These twe modes are selected by FRAME EQ or FRAME HO respectively.
The plotting may be done in rectangular coordinates using FRAME
HO or FRAME EQ, with no other argument. If other arguments are
given, a stereographic projection is used, which gives a better
representation of the sky (distorsion of shapes is not too serious,
but the scale of the map changes from the center of the projection to
the edges). The projection is defined by its center coordinates and
its size: for instance
FRAME EQ ra dec size
will use a projection centered in the requested direction, while the size parameter, in degrees, specify the plotting range (default is 180 degrees, i.e. a whole hemisphere). Similarly,
FRAME HO az el size
will produce a plot centered at the requested Azimuth and Elevation (in degrees). Caution: there are two possible azimuth definitions, depending on whether the azimuth is set to zero in the North or South direction. The SET AZIMUTH NORTH|SOUTH command allows one to select one or the other convention.
Use of SIC variables is allowed to select frames such as
FRAME EQ RA*12/PI DEC*180/PI 45
which selects a frame of size 45 degrees, in equatorial coordinates, centered on the last computed object position. A few short cuts are available to produce a number of useful, classical plots: