The command name is from the Hipad Plus the name of the Houston
Instruments digitizing tablet used to measure the rectangular positions on
cluster photographs. The positions were put in the hipad.xy file, as
a distinct source with respect to author's names when the data were taken
from the literature.
The command hpd has a specific option -info. It displays the entry for the given cluster in the file info.hpd located in the directory bda/information/ containing the scale of the xy positions and the source of the data. The cluster name has to be indicated on the command line.
> hpd -info 2287 extract the line relating to NGC 2287
> hpd -c display the number of the central star (0,0)
Selection can be made on the x or y or both parameters (xy).
> hpd xy -lt 20 select the stars within a box of 20 units in size
> hpd r -lt 20 select the stars within a circle of radius 20
A cluster chart may be built from the (x,y) positions and the magnitudes contained in the file hipad.xy. The same action may be obtained with carte.
> hpd -plt plot a chart from (x,y) positions