Using GWCS to Create the World Coordinate System Models for JWST Wide Field Slitless Modes

摘要

JWST will launch with two instruments onboard that enable wide-field slitless spectroscopy (WFSS) observations. Two grisms with perpendicular dispersion directions in each instrument will be available; use of both can mitigate overlapping spectra. In order to accurately represent the WCS of each of the grism exposures, a combination of the imaging mode distortion and pointing information is used in conjunction with the pointing information and dispersion solutions for the grism exposures. This allows us to create a single, general, WCS translation object that takes us between the detector coordinate system of the grism exposure and the sky coordinate system. This ncludes the translation between source location and the wavelength at the related dispersed pixel location. In order to successfully accomplish this the GWCS package was employed to create the final WCS object.