Science Instruments for the Giant Magellan Telescope

We describe the development status of the first generation of science instruments for the Giant Magellan Telescope (GMT) and the very broad range of first-light capabilities that they will deliver. The first-generation suite includes: visible and infrared spectrographs delivering a wide range of spectral resolution; an infrared, diffraction-limited imager; and a visible to near-infrared, extreme adaptive optics coronagraphic imager and spectrograph. G-CLEF, a visible light echelle designed for broad scientific use and for precision radial velocity measurements, is in fabrication. Instruments in the final design phase as of this publication, include: GMACS, a high-throughput, wide-field, multi-object spectrograph; GMTNIRS, a near- to thermal-infrared echelle spectrograph utilizing silicon immersion gratings to achieve a very compact design that delivers a fixed-format spectrum from 1-5µm in a single exposure; GMTIFS, a diffraction-limited, near-infrared, integral-field imager and spectrograph; and GMagAO-X, which has internal deformable mirrors coupled with a coronagraph to deliver extreme-AO resolution, high contrast imaging and spectroscopy of extrasolar planets, including nearby potentially habitable terrestrial worlds in reflected light. The first-generation suite also includes a robotic fiber-feeding system called MANIFEST, currently in conceptual design, that enables spectroscopy over the 20 arcmin field of view of the telescope and can feed GMACS, G-CLEF, and future near-IR spectrographs intended to work at atmospheric spatial resolutions. We also discuss the visible and infrared cameras (called ComCam and AOTC, respectively) that will be used for alignment, verification, and commissioning of the active and adaptive optics modes of the telescope, as well as enable early science and outreach activities.