An Open Source Injection and Recovery Tool and Measuring Transit Detection Efficiency in Ultracool Dwarfs Observed by K2

We develop an extension to an open source Python framework called “lightkurve” for high precision time series photometric signal injection and recovery with support for a range of astrophysical transients, including planetary transits, starspot rotation, stellar flares, and supernovae. These tools will provide support for measuring transit detection efficiency in ultracool dwarfs observed by K2. We are interested in our ability to recover various types of transits around dwarfs at the spectral type M/L transition; to investigate this, we inject transits that simulate planets from 0.5 to 3.5 Earth radii and of periods from 0.3 to 26 days and attempt to recover them. We find a threshold of detectability as a relation to orbital period and radius. These detection efficiencies allow us to calculate the probability of seeing planets around these stars as it relates to the planet occurrence rate for a certain type of planet. We can constrain the probability of seeing no planets around a given number of stars and put an upper limit on the planet occurrence rate. We have calculated an upper limit for planet occurrence for each type of planet around M/L dwarfs observed by K2.