MIKE (spectrograph)

MIKE (spectrograph). The Magellan Inamori Kyocera Echelle (MIKE) is a high-resolution, optical echelle spectrograph permanently mounted on the Magellan Telescopes at the Las Campanas Observatory in Chile. Commissioned in late 2003, it was designed to provide exceptional throughput and stability for detailed spectroscopic studies across a broad wavelength range. As a workhorse instrument for the Magellan community, MIKE has been pivotal in advancing research on galactic archaeology, quasar absorption lines, and the chemical composition of stars in the Milky Way and nearby dwarf galaxies.

Overview

MIKE is a double spectrograph that simultaneously captures blue and red optical spectra using two separate CCD cameras. It was constructed through a collaboration involving the Carnegie Institution for Science, the University of Arizona, and the University of Michigan, with significant funding from Kyocera founder Kazuo Inamori. The instrument is installed at the Nasmyth focus of both the Magellan I (Baade) and Magellan II (Clay) telescopes, allowing it to be used on either 6.5-meter primary mirror. Its design prioritizes high efficiency and spectral purity, making it one of the most sensitive high-resolution spectrographs in the world for its class.

Design and capabilities

The spectrograph utilizes a white-pupil echelle design, pioneered by instruments like the High Resolution Echelle Spectrometer (HIRES) at the W. M. Keck Observatory, to achieve high dispersion. Light is split by a dichroic beam splitter after passing through the slit, sending blue light to one arm and red light to another, each with its own cross-disperser and CCD detector. This provides continuous wavelength coverage from the atmospheric cutoff near 320 nm in the ultraviolet to 1000 nm in the near-infrared. MIKE offers two primary resolution modes: a standard mode with resolving powers of approximately 28,000 in the blue and 22,000 in the red, and a high-resolution mode using a narrower slit that can reach up to ~80,000 in a single echelle order.

Instrument components

Key optical components include a large R4 echelle grating for high-order dispersion, prism cross-dispersers, and high-efficiency camera lenses designed specifically for each arm. The detectors are thick, UV-enhanced CCDs manufactured by Semiconductor Technology Associates, chosen for their high quantum efficiency across the full bandpass. The spectrograph is housed in a massive, temperature-stabilized vacuum vessel to maintain optical alignment and minimize thermal expansion effects. Precision mechanisms control the slit width, Hartmann masks for focusing, and filters, with the entire instrument operated through a sophisticated software interface developed at the Carnegie Observatories.

Scientific applications and discoveries

MIKE's high sensitivity and broad wavelength coverage have enabled groundbreaking studies in several areas of astrophysics. It has been extensively used to measure precise abundances of r-process and s-process elements in metal-poor stars in the Galactic halo, informing models of nucleosynthesis and the early formation of the Milky Way. The instrument has characterized the intergalactic medium via absorption lines in the spectra of distant quasars and has studied the dynamics and chemistry of stars in Local Group galaxies like the Large Magellanic Cloud and Sagittarius Dwarf Spheroidal Galaxy. Notable discoveries include some of the most metal-poor stars known and detailed analyses of planetary nebulae in other galaxies.

Operational history

First light for MIKE was achieved on the Clay Telescope in November 2003, with routine science operations beginning in 2004. It quickly became one of the most requested instruments on the Magellan Telescopes. The spectrograph has undergone several upgrades, including CCD replacements and improvements to its image stabilization and data reduction pipeline. Managed by the Carnegie Institution for Science as part of the Las Campanas Observatory instrument suite, MIKE continues to be a heavily utilized facility, contributing to hundreds of publications and playing a key role in large spectroscopic surveys such as the Magellan Planet Search Program in its earlier phases. Category:Astronomical instruments Category:Spectrographs Category:Magellan Telescopes