This task displays a given image and plots the positions of sources listed in a separate sourcelist file.
The input image is specified via the parameter imageset and the sourcelist file (generated by eg eboxdetect, emldetect, srcmatch or ewavelet) is specified through the boxlistset parameter.
Circles are used to depict the source positions. The radius of these circles can be set using the sourceradius parameter. Alternatively the statistical error on the position error contained in the source list can be used by specifying useposerr=yes. In this case an additional systematic error may be added in quadrature using the syserr parameter.
An optional ID label can also be displayed alongside the circle, corresponding to the row number of that source in the input source list. This can be enabled through the uselabel parameter. This helps the user to refer back to source properties documented in the source list.
These circles are in fact Ds9-type regions, which can be written out to a file for future use (for example, when running a later DS9 session) by setting withregionfile to true, and specifying the desired file name via the regionfile parameter.
Note that the current version computes the regions in terms of equatorial coordinates, as opposed to raw image coordinates in previous versions. This means that the task can overlay source positions taken from a given source list onto any image, eg a PN sourcelist can be overlayed on a MOS1 image, as long as the image contains WCS information that maps the pixel grid onto equatorial coordinates.