# TTVFast: An efficient and accurate code for transit timing inversion problems

**Authors:** Katherine M. Deck, Eric Agol, Matthew J. Holman, David Nesvorny  
**arXiv:** [1403.1895](https://arxiv.org/abs/1403.1895)  
**Date:** 2014-03-07  
**Summary page:** https://www.summarizepaper.com/en/paper/1403.1895v1/

## Key points

- Transit timing variations (TTVs) are crucial in exoplanet research:
- Confirm Kepler planet candidates
- Detect non-transiting planets
- Determine masses and orbital elements in multi-planet systems
- Millions to billions of simulations for statistical assessments
- TTVFast is an efficient code developed by a team led by Katherine M. Deck, Eric Agol, Matthew J. Holman, and David Nesvorny:
- Uses symplectic integrator with Keplerian interpolator for rapid transit timing computations
- Prioritizes speed without compromising essential accuracy
- Allows users to adjust time step for desired precision levels tailored to specific planetary systems
- Comparative analysis shows significant speed-up compared to traditional dynamical integrations:
- Achieves at least an order of magnitude improvement in processing times
- Published in Astrophysical Journal (787:132), TTVFast is available in C and Fortran versions on GitHub:
- Represents a valuable contribution to the astronomical community
- Enhances understanding of exoplanetary dynamics through advanced computational techniques

## Summary

Transit timing variations (TTVs) have emerged as a crucial tool in the field of exoplanet research. They enable the confirmation of Kepler planet candidates, detection of non-transiting planets, and determination of masses and orbital elements within multi-planet systems. The computational demands associated with TTV analysis are substantial and often require millions to billions of simulations for statistical assessments. In response to these challenges, a team led by Katherine M. Deck, Eric Agol, Matthew J. Holman, and David Nesvorny developed TTVFast: an efficient code designed for rapid transit timing computations. Leveraging a symplectic integrator with a Keplerian interpolator, TTVFast prioritizes speed without compromising essential accuracy. While some precision is sacrificed in favor of computational efficiency, this trade-off is deemed acceptable given that transit times need not be calculated to levels beyond measurement uncertainties. One notable feature of TTVFast is its adaptability; users can adjust the time step to achieve desired precision levels tailored to specific planetary systems. The team's comparative analysis revealed a significant speed-up compared to traditional dynamical integrations employing high-precision Bulirsch-Stoer integrators – often achieving at least an order of magnitude improvement in processing times. Published in the Astrophysical Journal (787:132), this innovative software tool represents a valuable contribution to the astronomical community. Available in both C and Fortran versions on GitHub (http://github.com/kdeck/TTVFast), TTVFast stands as a testament to collaborative efforts aimed at enhancing our understanding of exoplanetary dynamics through advanced computational techniques. As researchers continue to explore new frontiers in exoplanet discovery and characterization, tools like TTVFast will play an instrumental role in unlocking the mysteries of distant worlds orbiting other stars.