The recent apparitions of periodic comets 21P/Giacobini-Zinner and 46P/Wirtanen have been intensively monitored.  The analysis and the enclosed plots made by Erik Bryssinck well show the preliminary results on the two objects. Comet 21P displayed a regular curve peaking about 18 days before perihelion in agreement with the 1998 apparition (Lara et al, A&A 399- 2003).

The asymmetry is more evident in the second plot reporting Afrho values vs. the heliocentric distance in AU.

46P/Wirtanen in its ascending curve is showing also a regular behavior as appears in the enclosed preliminary plot;Af[rho] is normalised for a zero solar phase angle.