Coma in Czerny-Turner spectrographs is compensated at more than one angle of diffraction if the grating angle is sufficiently great. Coma and spherical aberration are calculated for a specific case.
CHARLY D. ALLEMAND, "Coma Correction in Czerny-Turner Spectrographs," J. Opt. Soc. Am. 58, 159-160 (1968)