Pushing the precision limit of ground-based eclipse photometry

TL;DR

This paper demonstrates that ground-based telescopes can achieve sub-millimagnitude precision in eclipse photometry within a minute, challenging previous assumptions about atmospheric noise limitations.

Contribution

It introduces a method to reach sub-mmag precision in ground-based eclipse photometry within a minute, surpassing previous atmospheric noise constraints.

Findings

Achieved sub-mmag precision in a single eclipse observation

Demonstrated ground-based detection of small planets and secondary eclipses

Challenged the belief that atmospheric noise prevents high-precision ground photometry

Abstract

Until recently, it was considered by many that ground-based photometry could not reach the high cadence sub-mmag regime because of the presence of the atmosphere. Indeed, high frequency atmospheric noises (mainly scintillation) limit the precision that high SNR photometry can reach within small time bins. If one is ready to damage the sampling of his photometric time-series, binning the data (or using longer exposures) allows to get better errors, but the obtained precision will be finally limited by low frequency noises. To observe several times the same planetary eclipse and to fold the photometry with the orbital period is thus generally considered as the only option to get very well sampled and precise eclipse light curve from the ground. Nevertheless, we show here that reaching the sub-mmag sub-min regime for one eclipse is possible with a ground-based instrument. This has important implications for transiting planets characterization, secondary eclipses measurement and small planets detection from the ground.