hierarchical, non-parametric calibration

It being Wednesday, I worked today with many people. Many highlights! One was the following: With Lily Zhao (Yale), my loyal reader knows, I am calibrating the EXPRES spectrograph, which has both laser-frequency comb and thorium-argon lamp calibration data. Zhao and I have figured out that we can go both hierarchical and non-parametric with the calibration: Hierarchical in the sense that we will use all the calibration frames to calibrate every exposure, and non-parametric in the sense that we won't choose the order of a polynomial, we will use interpolation or a process.

Today we improved the order of operations for this project. At first we were interpolating, and then building the hierarchical model. But today (forced by computational cost) we realized that we can build the hierarchical model on the calibration data prior to the interpolation. That's lower dimensional. It sped things up a lot, and simplified the code. We did some robust things to deal with missing data, and Zhao did some clever things to make her code work with the arc lamp just as well as it does with the laser-frequency comb.

Our current plan is to assess our calibration quality by looking at the measured radial velocity (which should be exactly zero, I hope) of the thorium-argon lamps as calibrated by the LFC, and look at the velocity of the LFC as calibrated by the ThAr lamps. That is, a cross-validation between the lamps and the comb.