\label{eq:xdef}$$

The sky-plane positions of the radiants in the equatoreal and ecliptical grid are depicted in Figure 5. The radiant positions calculated using the nominal orbit of the comet C/1917 F1 Mellish and computed by several methods by DOSMETH software (@nes98) are shown as well.

![Cumulative distribution of absolute magnitudes of December Monocerotids and November Orionids.[]{data-label="F4"}](fig4.eps){width="8.0cm"}

![Equatoreal and ecliptical radiants (Eq. 2000.0) of December Monocerotids and November Orionids. Upper and lower right graphs show the radiants corrected for daily motion and reduced to the solar longitude of the activity maximum. Theoretical geocentric radiants derived by DOSMETH from the nominal orbit of C/1917 F1 Mellish are displayed as well (open circles).[]{data-label="F5"}](fig5.eps){width="8.0cm"}

A possible common origin of both meteor showers can also be inferred from Figure 6 depicting the heliocentric distance of the ascending and descending nodes of the MON and NOO as a function of solar longitude. As expected, the ascending node lies very close to the value of 1AU but the descending node gradually rises with the solar longitude and both meteor showers overlap without any gap or visible difference in the descending node.

Other common properties might be derived from the beginning and terminal heights of individual meteors. Figure 