This program makes a simple radial intensity plot of a section of an image. If the object is a star, it shows a mean point-spread function profile. An non-interactive version is available via the RPLOT command.
The radial intensity plot is formed by finding the radius to all points within a given box around the specified location and plotting intensity versus radius. Each point making up the plot is from a single pixel; no interpolation is done. The effect is to produce an azimuthally wrapped (not averaged) plot of intensity. For example, if doing TVRPLOT on the image of a star, if that star is round, then a fairly clean radial point-spread function profile, will be plotted. If the star is elliptical (due to bad guiding or focus), the radial brightness profile will be a fuzzy cloud of points.
The center of the radial plot may be specified in one of two ways:
NOERASE suppresses erasing of the plotting window, allowing you to superimpose subsequent radial plots on top of each other.
LOG will plot the logarithm of the intensity as a function of radius.
COLOR=c changes the color of the points plotted. The default color is white (1). At present only the 7 "primary" graphics colors are available:
Colors may be used in conjunction with NOERASE to overlay two different radial profiles, using the colors to distinguish them.
See RPLOT for the non-interactive (batch) version of this program.