APOGEE meeting, day 1

The annual APOGEE Collaboration meeting started in Cocoa Beach, FL today, following the AAS meeting. I presented to the Collaboration the best current results from The Cannon training on 15 abundances and two stellar parameters. I showed that The Cannon de-noises even the training set—that is, it returns labels that are even better than those on which it was trained! That's impossible of course, in an accuracy sense, but it can be true in a precision sense. (Our evidence comes from the precision with which The Cannon finds stars in the same open cluster to be mono-abundance.)

I proposed that The Cannon be incorporated into the APOGEE as a second stage of labeling after the physical-model-based labeling by their ASPCAP pipeline. There were many discussions about details of our results (from Melissa Ness, Andy Casey, and myself) and their comparisons with other pipelines and methods. It looks likely that my proposal will be accepted.

In another part of the meeting, Jennifer Johnson (OSU) proposed that Potassium might have a different supernova origin than is believed. She is basing that on it's covariance with other elements. I promised to deliver a methodologically correct answer to that question, which is in the area of causal inference.