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The Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) near-IR channelis extensively used in time-resolved observations, especially for transitingexoplanet spectroscopy and brown dwarf and directly imaged exoplanet rotationalphase mapping. The ramp effect is the dominant source of systematics in theWFC3 for time-resolved observations, which limits its photometric precision.Current mitigation strategies are based on empirical fits and requireadditional orbits "to help the telescope reach a thermal equilibrium". We showthat the ramp effect profiles can be explained and corrected with high fidelityusing charge trapping theories. We also present a model for this process thatcan be used to predict and to correct charge trap systematics. Our model isbased on a very small number of parameters that are intrinsic to the detector.We find that these parameters are very stable between the different datasets,and we provide best-fit values. Our model is tested with more than 120 orbits($\sim40$ visits) of WFC3 observations and is proved to be able to provide nearphoton noise limited corrections for observations made with both staring andscanning modes of transiting exoplanets as well as for starting-modeobservations of brown dwarfs. After our model correction, the light curve ofthe first orbit in each visit has the same photometric precision as subsequentorbits, so data from the first orbit need no longer be discarded. Near IRarrays with the same physical characteristics (e.g., JWST/NIRCam) may alsobenefit from the extension of this model, if similar systematic profiles areobserved.

the astronomical journal

A Physical Model-based Correction for Charge Traps in the Hubble Space  Telescope's Wide Field Camera 3 Near-IR Detector and Applications to  Transiting Exoplanets and Brown Dwarfs