Simple codes for animating a spot on a rotating star or a planet orbiting a star from various position angles.

Measuring rotation with K2

K2 Rotation Periods for Low-mass Hyads and the Implications for Gyrochronology Douglas et al. 2016, ApJ, 822, 47

I developed codes to extract light curves from K2 data using a moving aperture method, and to measure rotation periods using Lomb-Scargle periodograms. For a simple tutorial comparing Lomb-Scargle periodograms and autocorrelation functions for measuring rotation periods, see here.

Rotation and activity in Praesepe and the Hyades

The Factory and the Beehive II: Rotation and Activity in Praesepe and the Hyades
Douglas et al. 2014, ApJ, 795, 161

The catalogs for the Praesepe and Hyades clusters are available as extended tables through the journal. NOTE: the electronic tables incorrectly label R as the stellar radius; it is in fact the Rossby Number.

A tab-separated version of Table 8 from the paper, giving synthetic colors and chi values (for converting from Halpha equivalent widths to luminosity ratios), is here

In Section 4.3 we fit a saturation-type model to Halpha activity vs. Rossby number using the open-source MCMC code emcee. The code I wrote for that fit is on GitHub, and samples from the posterior distribution are available here