Galactic extinction

[sjoertvv]

Could it possible to allow input flux that is not corrected for Galactic extinction? In this case the user would have to give the Galactic "E(B-V)" as input (plus perhaps an option to pick a Cardelli law).

I am asking because the Galactic extinction in a given filter depends on the shape of the spectrum. For the narrow SDSS filters it hardly changes between galaxy type. However for broader filters (eg, Swift UVOT, Gaia G) the input spectrum can make a difference (up to ~0.3 mag).

I anticipate using uncorrected mags may not be possible without changes to FSPS. In that case I'm happy to guess the galaxy type from the observed colors to calculate corrected magnitudes. But this approach would not propagate the uncertainty related to the extinction correction into the final posterior.

[bd-j]

This is a good point, especially for higher redshift where internal and foreground reddening are not degenerate. There is currently no ability to add an extra foreground reddening. I don't think FSPS would be the right place to do this, since this is an observer frame effect. The required changes could be made in prospect.models.SpecModel.predict() though there'd need to be extinction curves added (e.g. from sedpy).

For now a guess for the corrections based on observed color is probably your best bet.