However, this degeneracy can be removed if several grism images of the same field are obtained which differ in the direction of the dispersion, e.g. with different roll angle of the telescope.
Other constraints can be obtained with direct images of the same field without the grism. If it is possible to reconstruct the position-wavelength data cube from such a data set, an observing strategy which obtains objective grism spectra at a number of orientation angles could under certain circumstances be a promising alternative to wavelength scanning strategies.
The advantage is that all incoming photons are recorded. The purpose of this work is to demonstrate the deconvolution of data taken in such a way and investigate observing strategies to maximize the information which can be recovered from a given total exposure time.