K2P$^2$ $-$ A photometry pipeline for the K2 mission

TL;DR

This paper introduces K2P$^2$, a comprehensive photometry pipeline designed to process K2 mission data by correcting for target drift and instrumental effects, significantly increasing usable light curves for asteroseismic and exoplanet studies.

Contribution

The paper presents a novel automated pipeline for K2 data that improves light curve extraction and correction, enabling more efficient analysis of targets affected by drift and instrumental noise.

Findings

Increases potential light curves by a factor of at least 10.

Effectively corrects for target drift and instrumental signals.

Applicable to future missions like TESS and PLATO 2.0.

Abstract

With the loss of a second reaction wheel, resulting in the inability to point continuously and stably at the same field of view, the NASA Kepler satellite recently entered a new mode of observation known as the K2 mission. The data from this redesigned mission present a specific challenge; the targets systematically drift in position on a ~6 hour time scale, inducing a significant instrumental signal in the photometric time series --- this greatly impacts the ability to detect planetary signals and perform asteroseismic analysis. Here we detail our version of a reduction pipeline for K2 target pixel data, which automatically: defines masks for all targets in a given frame; extracts the target's flux- and position time series; corrects the time series based on the apparent movement on the CCD (either in 1D or 2D) combined with the correction of instrumental and/or planetary signals via the KASOC filter (Handberg & Lund 2014), thus rendering the time series ready for asteroseismic analysis; computes power spectra for all targets, and identifies potential contaminations between targets. From a test of our pipeline on a sample of targets from the K2 campaign 0, the recovery of data for multiple targets increases the amount of potential light curves by a factor ${\geq}10$. Our pipeline could be applied to the upcoming TESS (Ricker et al. 2014) and PLATO 2.0 (Rauer et al. 2013) missions.