Add measurements of Lick indices

[biprateep]

It will be nice to get measurements of lick indices/absorption line equivalent widths, etc from the spectra.

[moustakas]

@biprateep how high priority is it for fastspecfit to measure Lick indices? There are a number of subtleties associated with these measurements (e.g., convolving the data to a specific instrumental resolution to bring the measurements onto the Lick system) that I'm not excited about doing in terms of the computational cost. I'm also not sure how many spectra will have enough signal-to-noise to yield a useful, e.g., H-delta_A measurement.

Could these measurements be done perhaps as an 'after-burner' on dedicated subsets of spectra / galaxies that satisfy certain criteria, including targeting criteria?

Thoughts?

[biprateep]

@moustakas In short: No it is not a very high priority, you can skip it for the next release.

I am measuring lick indices as an afterburner using an external library. I added this feature request so that all the measurements I was using come from a consistent processing pipeline. One thing we can do is to provide a set of functions that people can use if they want to get Lick indices for their specific work.

I did plan to work on it, currently I am on a break from working on K+A galaxies as I am working on editing and finishing up a paper, will get back to it in a month or so.

[moustakas]

Thanks, that sounds good. Is this the library you're using?
https://mfouesneau.github.io/docs/pyphot/licks.html
It looks awesome!

[biprateep]

Yup, this is the one I am currently using. I have seen plenty of others use it and its pretty good!

There's this very recent library (PyLick) dedicated to Lick indices I saw on arxiv a few weeks back. Will check this one out sometime. https://gitlab.com/mmoresco/pylick/