Provided measured fluxes for the appropriate molecular emission
bands, one can derive the production rates associated with these
fluxes in a straight-forward series of calculations. Needed
input: r in AU, Δ in AU, heliocentric velocity, v, in km/s,
aperture radius in arcsec.
Extract L/N (g-factors): Interpolated from look-up tables scaled
to 1 AU; then scale by r-2.
Compute the number of molecules within the observing aperture:
M(ρ) = 2.812E27 * Δ * Δ * Flux / L/N , where
the constant term is 4 * pi * AU-to-cm squared unit conversion.
Compute the column density within the observing aperture:
N(ρ) = M(ρ) / Area of aperture projected to the comet
[Note: column density is a near-useless quantity and is not
used for subsequent calculations.]
Compute Haser-fraction (what fraction of the total coma is
within the observing aperture): Look-up table of Haser parent
and daughter scalelengths, and parent and daughter
r-dependencies. Then use these values, plus r, Δ,
and aperture radius in a Haser model calculation.
Compute M(total): Extrapolate to the total number of molecules
in the entire coma by taking M(ρ) and dividing by the
Compute daughter lifetime: Extract from look-up table for 1 AU and
scale by r2.
Compute production rate (Q): Divide total number of molecules
from step 5, by daughter lifetimes from step 6. This yields
the destruction rate which, for static equilibrium, must be
equal to the production rate.
Note: For convenience, the logarithm for many of the previous
values is also calculated.