2014-09-03

calibration and search

A phone call between Wang, Foreman-Mackey, Schölkopf, and me started the day, and a conversation between Foreman-Mackey and me ended the day, both on the subject of modeling the structured noise in the Kepler data and the impact of such methods on exoplanet search. In the morning conversation, we discussed the relative value of using other stars as predictors for the target star (because co-variability of stars encodes telescope variability) compared to using the target star itself, but shifted in time (because the past and future behavior of the star can predict the present state of the star). Wang has a good system for exploring this at the pixel level. We gave him some final tasks before we reduce our scope and write a paper about it.

In the afternoon conversation, we looked at Foreman-Mackey's heuristic "information criteria" that he is using for exoplanet search in the Kepler data. By the end of the day, his search scalar included such interesting components as the following: Each proposed exoplanet period and phase is compared not just to a null model, but to a model in which there is a periodic signal but with time-varying amplitude (which would be a false positive). Each peak in the search scalar is vetoed if it shares transits with other, higher peaks (to rule out period aliasing and transit–artifact pairings). A function of period is subtracted out, to model the baseline created by noise (which is a non-trivial function of period). Everything looks promising for exoplanet candidate generation.

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