model derivatives

Today Yuan-Sen Ting (Harvard) gave Ness and me derivatives of Kurucz-like models of APOGEE spectral data with respect to individual element abundances and effective temperature and gravity. Ness and I plotted these theoretical derivatives against “beliefs” obtained by The Cannon sbout these same dependencies. They agree remarkably well! But in detail they disagree; it remains to figure out what parts of the disagreement are noise or real results. We also showed (based on the derivative vectors) that the precisions with which APOGEE can detect or measure individual abundances are very, very high.

In other news, I found and fixed bugs in my star-formation history code, but none of the bug fixes led to reasonable results. Time to write some tests.

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