K2P$^2$: Reduced data from campaigns 0-4 of the K2 mission

TL;DR

This paper introduces the K2P2 pipeline for extracting and correcting light curves from the K2 mission data, providing high-quality data for thousands of targets, including extended objects, and compares its performance with other pipelines.

Contribution

The paper presents the K2P2 pipeline for efficient light curve extraction and correction from K2 data, enabling analysis of a larger number of targets than previous methods.

Findings

K2P2 extracts light curves for ~160,000 targets from campaigns 0-4.

K2P2 performs as well or better than other pipelines in photometric quality.

The pipeline also effectively handles extended objects like galaxies.

Abstract

Context: After the loss of a second reaction wheel the Kepler mission was redesigned as the K2 mission, pointing towards the ecliptic and delivering data for new fields approximately every 80 days. The steady flow of data obtained with a reduced pointing stability calls for dedicated pipelines for extracting light curves and correcting these for use in, e.g., asteroseismic analysis. Aims: We provide corrected light curves for the K2 fields observed until now (campaigns 0-4), and provide a comparison with other pipelines for K2 data extraction/correction. Methods: Raw light curves are extracted from K2 pixel data using the "K2-pixel-photometry" (K2P$^2$) pipeline, and corrected using the KASOC filter. Results: The use of K2P$^2$ allows for the extraction of the order of 90.000 targets in addition to 70.000 targets proposed by the community - for these, other pipelines provide no data. We find that K2P$^2$ in general performs as well as, or better than, other pipelines for the tested metrics of photometric quality. In addition to stars, pixel masks are properly defined using K2P$^2$ for extended objects such as galaxies for which light curves are also extracted.