the state of a spectrograph in calibration space

I did two bits of research with Lily Zhao (Yale) and Megan Bedell (Flatiron) today. One is that we opened up (with a shared screen) the outline of the Zhou's paper on Excalibur, our project to build a hierarchical, non-parametric calibration of the EXPRES spectrograph (and others). We re-organized it and outlined it and figured out remaining tasks for completion.

Zhao and I also discussed some matters relating to measuring the location in the spectrograph of the trace, which is 80-ish stripes on the detector laid down by the 80-ish echelle orders. The idea that we have—which is speculative—is that the locations of the traces might provide a kind of “simultaneous reference” for the wavelength solution. We can show that the spacecraft calibration state varies in a low-dimensional space; that means that we don't need all that much information to find and track the state. Maybe the trace positions will provide that information?! If so, we have given all spectrographs a simultaneous reference, whether they wanted it or not!