Precise Near-infrared Occultation of WASP-19b with FourStar on Magellan

Abstract We describe the setup and procedure to obtain precise near-infrared photometry with the FourStar imager on the 6.5 m Magellan Baade Telescope at Las Campanas Observatory, which enabled the recovery of a 2316 ± 170 ppm secondary occultation (13.5 σ ) in the K s filter for the ultra hot-Jupiter WASP-19b. The unbinned residuals are ∼1400 ppm in 11.6 s and bin to 660 ppm in 1 minute bins or 180 ppm in 15 minutes bins.