Introduction

Single-grain dating has become common practice in fission track, 40Ar/39Ar, U-Pb and luminescence dating. Each of these radiometric dating techniques is affected by various sources of analytical uncertainty, which may range from the percent level (e.g., U/Pb) to tens of percents (e.g., apatite fission tracks). Furthermore, the analytical uncertainty may, and generally does, vary from grain to grain. Various graphical tools have been proposed to aid in the interpretation of such 'heteroscedastic' data. DensityPlotter and RadialPlotter are two closely related programs developed with the aim to make these methods more accessible to the geochronological community. Both programs offer exactly the same functionality, albeit with a different set of preloaded preferences: The graphical output can be saved either in a .png image format, or in a .pdf vector format which can be edited in Adobe Illustrator, CorelDraw, or Inkscape. These help pages provide some basic instructions about both programs, as well as pointers to the theoretical underpinnings of the methods used. Users are encouraged to report bugs or give feedback to the author either by email (p.vermeesc@ucl.ac.uk) or on the feedback forms at http://densityplotter.london-geochron.com and http://radialplotter.london-geochron.com