Photometric stability analysis of the Exoplanet Characterisation Observatory

TL;DR

This paper assesses how spacecraft pointing and temperature fluctuations impact the photometric stability of the EChO mission, crucial for accurate exoplanet spectroscopy, through simulations of HD189733b observations.

Contribution

It introduces a method to quantify the effects of pointing and temperature instabilities on the EChO spectroscopic measurements.

Findings

Pointing instabilities significantly affect photometric accuracy.

Temperature fluctuations contribute to spectral errors.

Simulations help define stability requirements for the mission.

Abstract

Photometric stability is a key requirement for time-resolved spectroscopic observations of transiting extrasolar planets. In the context of the Exoplanet Characterisation Observatory (EChO) mission design, we here present and investigate means of translating spacecraft pointing instabilities as well as temperature fluctuation of its optical chain into an overall error budget of the exoplanetary spectrum to be retrieved. Given the instrument specifications as of date, we investigate the magnitudes of these photometric instabilities in the context of simulated observations of the exoplanet HD189733b secondary eclipse.