#tellurics, day 1

Today was the first day of the Telluric Line Hack Week at Flatiron. We got an amazing crowd to New York, to discuss (and, of course, hack on) some pretty technical matters. But of course this is really about extremely high precision radial-velocity spectroscopy, and this is a community that is detail-oriented, technical, and careful!

The first day was a get-to-know-each-other day, in which we introduced ourselves, and then talked through existing projects, data sets, and instruments. I learned a huge amount today; I'm reeling! Here are a few very subjective highlights:

In the introductions, some common themes appeared. For example, many people using physical models for tellurics want to become more data-driven, and people using data-driven techniques want to be more physics-motivated. So there is a great opportunity this week for hybrid methods, that make use of the physical models, but only use data-driven approaches to model residuals away from the physical models.

Information theory came up more than once; we might do a break-out on this. In particular, we discussed the point (that I love) that what is traditionally done in fitting for RVs is an approximation to the Right Thing To Do (tm), possibly with slightly more robustness. Bedell and I really really ought to write a paper on this! But it is interesting and non-trivial to understand what techniques saturate measurement bounds, and under what assumptions. Unfortunately you can't ask these questions without making very strong assumptions.

In the discussion of hardware details, I was even more motivated than usual to say that we ought to be doing our RV fitting in the two-dimensional spectrograph data (rather than extracting to one dimensional spectra first). I was surprised to learn that many of the hardware people in the room agreed with that! So this seems like a productive direction to start looking.

Sharon Wang (DTM) is doing some interesting work trying to figure out what is really the noise floor from unmodeled telluric features in the atmosphere. That is a great question! She is asking it to bolster or criticize or set the context for going to space. Should we be doing RV in space?

Very excitingly for me, there was lots of enthusiasm in the room for learning about and trying wobble, which is Bedell's method and software for simultaneous data-driven fitting of tellurics and star. The discussion at the end of the day was all about this method, and the questions in the room were excellent, awesome, and frightening. But if all goes well we will launch quite a few projects this week.