2017-11-07

noise, calibration, and GALAH

Today I gave my second of five Hunstead Lectures at University of Sydney. It was about finding planets in the Kepler and K2 data, using our non-stationary Gaussian Process or linear model as a noise model. This is the model we wrote up in our Research Note of the AAS. In the question period, the question of confirmation or validation of planets came up. It is very real that the only way to validate most tiny planets is to make predictions for other data. But when will we have data more sensitive than Kepler? This is a significant problem for much of bleeding-edge astronomy.

Early in the morning I had a long call with Jason Wright (PSU) and Bedell (Flatiron) about the assessment of the calibration programs for extreme-precision RV surveys. My position is that it is possible to assess the end-to-end error budget in a data-driven way. That is, we can use ideas from causal inference to figure out what parts of the RV noise are coming from telescope plus instrument plus software. Wright didn't agree: He believes that large parts of the error budget can't be seen or calibrated. I guess we better start writing some kind of paper here.

In the afternoon I had a great discussion with Buder (MPIA), Sharma (USyd), and Bland-Hawthorn (USyd) about the current status of detailed elemental abundance measurements in GALAH. The element–element plots look fantastic, and clear trends and high precision are evident, just looking at the data. To extract these abundances, Buder has made a clever variant of The Cannon which makes use of the residuals away from a low-dimensional model to measure the detailed abundances. They are planning on doing a large data release in April.

No comments:

Post a Comment