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dc.contributor.authorZhou, Yifan*
dc.contributor.authorApai, Dániel*
dc.contributor.authorLew, Ben W. P.*
dc.contributor.authorSchneider, Glenn*
dc.date.accessioned2017-08-25T20:21:58Z
dc.date.available2017-08-25T20:21:58Z
dc.date.issued2017-05-04
dc.identifier.citationA Physical Model-based Correction for Charge Traps in the Hubble Space Telescope’s Wide Field Camera 3 Near-IR Detector and Its Applications to Transiting Exoplanets and Brown Dwarfs 2017, 153 (6):243 The Astronomical Journalen
dc.identifier.issn1538-3881
dc.identifier.doi10.3847/1538-3881/aa6481
dc.identifier.urihttp://hdl.handle.net/10150/625388
dc.description.abstractThe Hubble Space Telescope Wide Field Camera 3 (WFC3) near-IR channel is extensively used in time-resolved observations, especially for transiting exoplanet spectroscopy as well as. brown dwarf and directly imaged exoplanet rotational phase mapping. The ramp effect is the dominant source of systematics in the WFC3 for time-resolved observations, which limits its photometric precision. Current mitigation strategies are based on empirical fits and require additional orbits to help the telescope reach a thermal equilibrium. We show that the ramp-effect profiles can be explained and corrected with high fidelity using charge trapping theories. We also present a model for this process that can be used to predict and to correct charge trap systematics. Our model is based on a very small number of parameters that are intrinsic to the detector. We find that these parameters are very stable between the different data sets, and we provide best-fit values. Our model is tested with more than 120 orbits (similar to 40 visits) of WFC3 observations. and is proved to be able to provide near photon noise limited corrections for observations made with both staring and scanning modes of transiting exoplanets as well as for starting-mode observations of brown dwarfs. After our model correction, the light curve of the first orbit in each visit has the same photometric precision as subsequent orbits, so data from the first orbit no longer need. to. be discarded. Near-IR arrays with the same physical characteristics (e.g., JWST/NIRCam) may also benefit from the extension of this model if similar systematic profiles are observed.
dc.description.sponsorshipNASA Earth and Space Science Fellowship Program [NNX16AP54H]; Technology Research Initiative Fund (TRIF) Imaging Fellowship, University of Arizona; National Aeronautics and Space Administration [NNX15AD94G]; NASA through a grant from Space Telescope Science Institute [12314, 13418, 14241]; NASA [NAS5-26555]en
dc.language.isoenen
dc.publisherIOP PUBLISHING LTDen
dc.relation.urlhttp://stacks.iop.org/1538-3881/153/i=6/a=243?key=crossref.d8632f701456202d40ec5de454a41fffen
dc.rights© 2017. The American Astronomical Society. All rights reserved.en
dc.subjectbrown dwarfsen
dc.subjectinstrumentation: detectorsen
dc.subjectplanets and satellites: atmospheresen
dc.titleA Physical Model-based Correction for Charge Traps in the Hubble Space Telescope’s Wide Field Camera 3 Near-IR Detector and Its Applications to Transiting Exoplanets and Brown Dwarfsen
dc.typeArticleen
dc.contributor.departmentUniv Arizona, Dept Astron, Steward Observen
dc.contributor.departmentUniv Arizona, Dept Planetary Sci, Lunar & Planetary Laben
dc.identifier.journalThe Astronomical Journalen
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en
dc.eprint.versionFinal published versionen
refterms.dateFOA2018-07-15T00:37:36Z
html.description.abstractThe Hubble Space Telescope Wide Field Camera 3 (WFC3) near-IR channel is extensively used in time-resolved observations, especially for transiting exoplanet spectroscopy as well as. brown dwarf and directly imaged exoplanet rotational phase mapping. The ramp effect is the dominant source of systematics in the WFC3 for time-resolved observations, which limits its photometric precision. Current mitigation strategies are based on empirical fits and require additional orbits to help the telescope reach a thermal equilibrium. We show that the ramp-effect profiles can be explained and corrected with high fidelity using charge trapping theories. We also present a model for this process that can be used to predict and to correct charge trap systematics. Our model is based on a very small number of parameters that are intrinsic to the detector. We find that these parameters are very stable between the different data sets, and we provide best-fit values. Our model is tested with more than 120 orbits (similar to 40 visits) of WFC3 observations. and is proved to be able to provide near photon noise limited corrections for observations made with both staring and scanning modes of transiting exoplanets as well as for starting-mode observations of brown dwarfs. After our model correction, the light curve of the first orbit in each visit has the same photometric precision as subsequent orbits, so data from the first orbit no longer need. to. be discarded. Near-IR arrays with the same physical characteristics (e.g., JWST/NIRCam) may also benefit from the extension of this model if similar systematic profiles are observed.


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