Spurious frequencies in the {\it Kepler} short cadence data

TL;DR

This study investigates artifacts in Kepler short cadence data, identifying recurring spurious frequencies likely originating from spacecraft reaction wheels or temperature variations, with implications for data analysis accuracy.

Contribution

It introduces a Fourier-based method to detect and analyze periodic artifacts in Kepler data, revealing new types of spurious frequencies and their evolution over time.

Findings

Identified two new periodic artifact combs in Kepler data.

Artifacts evolve annually with spacecraft rotations.

Likely sources are reaction wheels or temperature changes.

Abstract

We present our search for artifacts in the {\it Kepler} short cadence data using a commonly known Fourier technique. We analyzed data on a monthly basis searching for a possible correlation between artifacts and the events attributed to the spacecraft as potential sources of the spurious frequencies. We defined a peak to be an artifact if it shows in at least two, yet preferentially most of the stars, during a given month. Besides the commonly known LC {\it comb} we found a periodic appearance of another two {\it combs}, one single artifact and very strange wide artifacts roaming between 10 and 35 c/d. These artifacts evolve on a yearly basis (four of {\it Kepler's} rolls) and we may only speculate that their sources are in the reaction wheels since they are the only moving parts or temperature variation. The orientation of the spacecraft is likely excluded from the possible sources. More resources are needed to provide a definite explanation of the artifacts.