Error distributions
The standard errors on the astrometric and photometric parameters, as determined by the Hipparcos data reductions, are displayed as a function of stellar magnitude. This can be done either colour coded with the ecliptic latitude of the source, or monochrome, in a colour selected by the user. The graphs to be shown are selected by means of the check boxes, and either astrometric or photometric graphs are shown. As the astrometric errors can be affected by duplicity, there is the option to include or not non-single stars. For the photometry there is the additional option of a so-called normalized graph, where the errors are normalized based on a Poisson error proportional to the flux of a star. The button Show graphs will activate the Error Distributions Display window.