This task reads one or more external catalogues in the FITS table format, where both the FITS filename and Table name can be specified by users. If the latter is omitted, it is assumed the first extention of the FITS file is the source list table.
The source-list tables can contain an arbitrary number of columns. The two of them must be Right Ascention and Declination in J2000 in unit of degree with Real type. In default the column names for those are RA and DEC, however users can explicitly specify them by colnamestyle=user with colra and coldec, respectively. Note that these two parameters accept a list, the order of which must be the same as that of the source list. If only one element is specified for either or both of those two parameters, that value is used for all the input source-lists.
The source-list tables can contain an arbitrary number of rows. Users can filter out some sources in them by stating the filtering conditions with expressions, where the columns in the table are used as a parameter. Note that the columns used in expressions must exist in the FITS file. expressions accepts a list, the order of which is the same as that of the source list; in other words users can apply different filtering conditions for different input source-lists.
After filtering out uninteresting, perhaps weak, sources, this task outputs a mask file, in which the positions of the sources are masked out as a filled circle. The radius of the circle can be a fixed value radius (when radiusstyle=fixed (default); in unit of arcsec), or alternatively the input source-list files can offer a column that lists the radius in arcsec for each source. In the latter case, radiusstyle=column and the list of the column names of it for each input source-list colradius (Default: RADIUS) can be specified.
In default, those areas regarded to be affected with optical-loading have the value of zero, and the rest, one. This behaviour can be inverted with isinverted=no. The default behaviour is convenient to use of the output mask file with dpssflag.
