**Justin Ripley, Princeton University** "Modeling the 'ringdown' of a Kerr black hole"

We present on progress to compute the second order metric perturbation of a Kerr black hole. We will first introduce the Teukolsky equation, and explain how it is used to understand first order perturbations of a Kerr black hole. We will then outline our motivations for this project: (1) to understand the regime of applicability of the Teukolsky equation in describing the ringdown of the Kerr black hole formed after the merger of two similar mass compact objects, and (2) to understand the proposed onset of "gravitational wave turbulence" around very rapidly spinning Kerr black holes. Time permitting we will show movies (simulations) of some of our preliminary results.

**Joseph van der List, Princeton University** "Frequency-domain Foregrounds in SPIDER Data"

One of the most important challenges in contemporary CMB observation is proper treatment of galactic foregrounds. The various galactic foregrounds, including thermal dust and synchrotron, have different frequency behaviors which can be used to separate them. Given a model for each component, parameters can be fit to data across a broad frequency range using Markov Chain Monte Carlo algorithms. I will present preliminary results from this method in SPIDER's region with WMAP, Planck, and SPIDER data.