Motion of the Perseid geocentric radiant. Right ascension (panel a), declination (panel b), and velocity (panel c) are plotted as a function of solar longitude (all in FDJ2000_0) for individual meteoroids with formal error bars. The sizes of the additional circles in plot b are proportional to velocity to show the correlation between declination and velocity. The data fit is plotted as a dotted line in all plots and the corresponding equation is inserted (no change of velocity with solar longitude was assumed). The motion of the mean radiant as reported by authors cited in the IAU Meteor Data Center is plotted by solid lines as follows: 2–5 see caption of Fig. 16; 6 – Kresák & Porubcan (1970).