z'-band Ground-Based Detection of the Secondary Eclipse of WASP-19b

TL;DR

This paper reports the ground-based detection of the secondary eclipse of exoplanet WASP-19b in the z'-band, confirming previous infrared measurements and analyzing the planet's atmospheric properties.

Contribution

First ground-based detection of WASP-19b's secondary eclipse in the z'-band, with detailed error correction and comparison to atmospheric models.

Findings

Eclipse depth of 0.088 extpm0.019% measured

Eclipse timing consistent with a circular orbit

Results align with previous infrared observations

Abstract

We present the ground-based detection of the secondary eclipse of the transiting exoplanet WASP-19b. The observations were made in the Sloan z'-band using the ULTRACAM triple-beam CCD camera mounted on the NTT. The measurement shows a 0.088\pm0.019% eclipse depth, matching previous predictions based on H- and K-band measurements. We discuss in detail our approach to the removal of errors arising due to systematics in the data set, in addition to fitting a model transit to our data. This fit returns an eclipse centre, T0, of 2455578.7676 HJD, consistent with a circular orbit. Our measurement of the secondary eclipse depth is also compared to model atmospheres of WASP-19b, and is found to be consistent with previous measurements at longer wavelengths for the model atmospheres we investigated.