The Gladders Image-Slicing Multislit Option (GISMO) for the Magellan I telescope's Inamori Magellan Areal Camera and Spectrograph (IMACS) will be developed to allow high-efficiency spectroscopy of regions in which the targets are closely packed or where the targets are compact. The goal will be achieved through the use of an image-reformatter to feed the wide-field reimaging spectrograph. The reformatter will unpack slices 24 arc seconds high and a few arc minutes long from the center of the field and redirect them to take advantage of the entire 16 x 16 arc minute field of the spectrograph. The development of this instrument will allow even more ambitious versions at other telescopes.
