Molecule   Parent  Daughter
             Scalelength
OH         2.4e4    1.6e5 
NH         5.0e4    1.5e5
CN         1.7e4    3.0e5
C3         3.1e3    1.5e5
CH         7.8e4    4.8e3
C2         2.5e4    1.2e5
NH2        4.1e3    6.2e4

C2 parent scales as heliocentric distance to the 2.5 power;
all others scale as helicentric distance squared.

The velocity is 0.85 km/sec at 1au and scales as heliocentric
distance to the -0.5 power.