Comparison of the activity characteristics of comet E3 (see Sect. 3.1 and Sect. 4.2) with those of comets belonging to different types (see Appendix A). (a) Brightness index vs. heliocentric distance of comet E3, long-period comets, and short-period comets. (b) Dust production rates vs. the heliocentric distance of comet E3, long-period comets, and short-period comets. The error bars of the E3 production rates are obscured by the data points. The two vertical dashed lines represent the heliocentric distances of 1.7 and 3.4 AU, respectively, within the range of which the observations of comet E3 that were used for analysis in this study were taken (see Table 1). It should be noted that the data of the listed brightness profiles and dust production rates are from two different literature collections.