APOSTLE: Eleven Transit Observations of TrES-3b

TL;DR

This study presents an improved analysis of eleven transits of TrES-3b, refining system parameters and confirming the absence of transit timing variations or additional planetary companions.

Contribution

The paper introduces an updated analysis protocol for transit data, achieving more precise system parameters and applying it to a comprehensive dataset of TrES-3b transits.

Findings

Refined system parameters with 10-30% smaller errors.

No evidence found for transit timing variations.

Ruled out certain planetary companions in resonance.

Abstract

The Apache Point Survey of Transit Lightcurves of Exoplanets (APOSTLE) observed eleven transits of TrES-3b over two years in order to constrain system parameters and look for transit timing and depth variations. We describe an updated analysis protocol for APOSTLE data, including the reduction pipeline, transit model and Markov Chain Monte Carlo analyzer. Our estimates of the system parameters for TrESb are consistent with previous estimates to within the 2\sigma\ confidence level. We improved the errors (by 10--30%) on system parameters like the orbital inclination ($i_{\text{orb}}$), impact parameter (b) and stellar density (\rho$_{\star}$) compared to previous measurements. The near-grazing nature of the system, and incomplete sampling of some transits, limited our ability to place reliable uncertainties on individual transit depths and hence we do not report strong evidence for variability. Our analysis of the transit timing data show no evidence for transit timing variations and our timing measurements are able to rule out Super-Earth and Gas Giant companions in low order mean motion resonance with TrES-3b.