Units of extinction curves

[mdecleir]

It is not clear what units the different extinction curves are given in, e.g. A(lambda)/A(V) or E(lambda-V)/E(B-V).

I think, ideally, all curves should have the same units.

At a minimum, the units should be reported in the tables here: https://dust-extinction.readthedocs.io/en/latest/dust_extinction/choose_model.html

[TheSkyentist]

Extinction models in this package are parametrized as A(lam)/A(V). So calling model(lambda) will return the A(lam)/A(V) values.

[karllark]

Correct. Except for the FM90 model. This one returns E(lambda-V)/E(B-V) as these are the units in the literature for most of the FM90 parameters reported. Would be good to get this into the docs for sure.

[TheSkyentist]

Interesting I hadn’t realized, actually it may be useful to also highlight the differences with the "Shape" models, since these do not provide the same "extinguish" method compared to the others.

[karllark]

Good point.