# Ephemeris refinement of 21 Hot Jupiter exoplanets with high timing uncertainties

## TL;DR

This study refines the predicted transit times of 21 Hot Jupiter exoplanets with large initial uncertainties, enabling more precise scheduling of future observations over the next decade.

## Contribution

The paper presents new, more accurate ephemerides for 21 Hot Jupiter exoplanets by analyzing extensive transit data, reducing timing uncertainties significantly.

## Key findings

- Refined ephemerides predict transit times with less than 6-minute uncertainty in 2018.
- Achieved transit timing deviations of up to 3.5 hours for some targets.
- Improved scheduling accuracy for follow-up observations over the next decade.

## Abstract

Transit events of extrasolar planets offer a wealth of information for planetary characterization. However, for many known targets, the uncertainty of their predicted transit windows prohibits an accurate scheduling of follow-up observations. In this work, we refine the ephemerides of 21 Hot Jupiter exoplanets with the largest timing uncertainty. We collected 120 professional and amateur transit light curves of the targets of interest, observed with 0.3m to 2.2m telescopes, and analyzed them including the timing information of the planets discovery papers. In the case of WASP-117b, we measured a timing deviation compared to the known ephemeris of about 3.5 hours, for HAT-P-29b and HAT-P-31b the deviation amounted to about 2 hours and more. For all targets, the new ephemeris predicts transit timings with uncertainties of less than 6 minutes in the year 2018 and less than 13 minutes until 2025. Thus, our results allow for an accurate scheduling of follow-up observations in the next decade.