batman: BAsic Transit Model cAlculatioN in Python

Abstract

I introduce batman, a Python package for modeling exoplanet transit light curves. The batman package supports calculation of light curves for any radially symmetric stellar limb darkening law, using a new integration algorithm for models that cannot be quickly calculated analytically. The code uses C extension modules to speed up model calculation and is parallelized with OpenMP. For a typical light curve with 100 data points in transit, batman can calculate one million quadratic limb-darkened models in 30 seconds with a single 1.7 GHz Intel Core i5 processor. The same calculation takes seven minutes using the four-parameter nonlinear limb darkening model (computed to 1 ppm accuracy). Maximum truncation error for integrated models is an input parameter that can be set as low as 0.001 ppm, ensuring that the community is prepared for the precise transit light curves we anticipate measuring with upcoming facilities. The batman package is open source and publicly available at https://github.com/lkreidberg/batman .Comment: 13 pages, 3 figures, accepted to PASP; this version adds an eclipse model and modifies transit parameterization in response to refere

An Ultra-short Period Rocky Super-Earth with a Secondary Eclipse and a Neptune-like Companion around K2-141

“…We modeled the normalized light curve using the batman transit model (Kreidberg 2015). We assumed the planets were non-interacting with zero-eccentricity orbits.…”

Four Sub-Saturns with Dissimilar Densities: Windows into Planetary Cores and Envelopes

“…For each light curve, we masked out the in-transit points and modeled the out-of-transit photometry with a Gaussian Process (Rasmussen & Williams 2005) using a squaredexponential kernel with a correlation length of 2 days. We then performed a standard MCMC exploration of the likelihood surface using the batman (Kreidberg 2015) and emcee Python packages to map out parameter uncertainties and covariances. Figure 3 summarizes the results of these different fits.…”

“…We are most fortunate to have the opportunity to conduct observations from this mountain. (Goodman & Weare 2010;Foreman-Mackey et al 2013), SME (Brewer et al 2015), isochrones (Morton 2015), k2sc (Aigrain et al 2015), batman (Kreidberg 2015), radvel (https://github.com/CaliforniaPlanet-Search/radvel), k2phot (https://github.com/petigura/ k2phot).…”

K2-66b and K2-106b: Two Extremely Hot Sub-Neptune-size Planets with High Densities

“…In brief, our code employs the MCMC package emcee (Foreman-Mackey et al 2013), and model light curves are generated using the Python package BATMAN (Kreidberg 2015). The model parameters are time of conjunction (T conj ); orbital period, eccentricity, inclination, and longitude of periastron (P e, i, and ω); scaled semimajor axis ( To analyze the RV time series of K2-66 and K2-106, we used the RV fitting package RadVel (B. Fulton & E. Petigura 2017, in preparation), which is publicly available on GitHub.…”