Slitless spectroscopy is used for astronomical surveys and in fields, such as solar physics, where time evolution is important.
The Crossley telescope utilized a slitless spectrograph that was originally employed by Nicholas Mayall.
[1] The Henry Draper Catalogue, published 1924, contains stellar classifications for hundreds of thousands of stars, based on spectra taken with the objective prism method at Harvard College Observatory.
The work of classification was led initially by Williamina Fleming and later by Annie Jump Cannon, with contributions from many other female astronomers including Florence Cushman.
[2] Slitless spectrographs encounter an unusual form of specular reflection at the grating, which leads to anisotropic image distortion called Littrow expansion or compression.