The W.M. Keck Observatory (WMKO)
Built close to the 13,600 ft summit of Mauna Kea in Hawaii, the W.M. Keck Observatory is an invaluable and unrivaled resource for Caltech staff and students. Operational for over 15 years, the two Keck 10-meter mirrors are the largest optical telescopes in the world. Each mirror consists of 36 hexagonal segments that work together to form a single reflective surface.
Access to the Keck Observatory is highly prized. Observing time at the two telescopes is divided among Caltech (which holds 36.5% share), the University of California, NASA, and the University of Hawaii.
Keck is one of the - if not the - most influential ground based observatories operating today. The observatory leads all others in scientific publications per telescope, and even more importantly, leads in the impact of those publications in the field of astronomy. Keck has been essential in seeking answers to the most fundamental questions in science: How did the universe evolve to its present state? How, and when, did galaxies form? What is the rate of star formation in galaxies far away, and far back in time? How much does the expansion rate of the universe vary over its history? How old are the oldest stars in our own galaxy? How do solar systems form? Where is the missing mass of the universe? In just the past few years, astronomers at the W.M. Keck observatory have made tremendous progress in answering these and other questions.
Among numerous ongoning research projects, Keck astronomers are using gravitational lenses to discover galaxies at the edge of the universe, using supernovae to determine the expansion rate of the universe, searching for atomic gases in the immense regions of space between galaxies, uncovering the nature of obscured galaxies, finding the most metal-poor stars, studying accretion and outflow processes in young stellar populations, discovering planets around other stars, pushing downward toward Earth-mass objects, and recently obtaining the first direct "family portrait" images of such planets.
Carrying out all of this exciting science requires not only a telescope and its infrastructure, but a suite of back-end instruments that sort and collect the photons. Keck incorporates a wide range of instruments. Included in the optical arsenal is the world's most powerful multi-object spectrograph (DEIMOS), the world's most sensitive spectrograph (LRIS), and a very stable echelle spectrometer (HIRES). Keck's performance is extended into the near-infrared with a suite of advanced instruments. NIRSPEC is a sensitive spectrograph operational at both high and low resolution. NIRC-2, a second generation near-infrared camera works with the Keck Adaptave Optics (AO) system to produce the highest spatial resolution ground-based images and spectroscopy in the 1-5 micron range. Additionally, there is the OH-Suppressing Infrared Imaging Spectrograph (OSIRIS), which is also fed by the AO system and obtains a spectrum at every diffraction-limited point across its field of view. The AO system is operational in either a "natural guide star" mode which required bright objects near the field of interest, or by making use of a laser launch telescope and return system which provides a "laser guide star" mode in any part of ths sky. The combination of adaptive optics and large mirrors enables Keck to exceed the imaging quality of the Hubble Space Telescope, and with greater photon-gathering power.
The twin Keck telescopes can also act in accord as an interferometer with an 85-meter baseline. Working in the interferometer mode and applying AO corrections to the fluctuation of the atmosphere, Keck can achieve an extraordinary resolution of 5 milliarcseconds. Recently added capabilities include spectrophotometry available over the H,K, and L-band (1.6-3.3 mictron) atmospheric windows. The interfometer also works at N-band (10 micron) where it obtains data in a nulling mode to look for extended mid-IR structure around bright objects such as stars and active galactic nuclei (AGN).
Caltech takes a leading role in the development of new instruments for Keck. A recent example is the new Multi Object Spectrometer for Infrared Exploration (MOSFIRE), an ambitions near-IR multiobject spectrograph and imager that has been developed, integrated, and tested in the highbay lab at Caltech, and will see first light in Hawaii later this year. Caltech engineers and scientists are also involved in the Next Generation Adaptive Optics (NGAO) project which aims to both improve the performance of AO at near-IR wavelengths and to extend the availability of AO to optical wavelengths. Other advanced instrumentation concepts are being discussed, with the goal of keeping Keck firmly placed at as the forefront facility for ground-based optical and near-IR astronomy.
[Image credits: Laurie Hatch, © lauriehatch.com]
Text maintained by Matthew Schenker <schenker [at] astro.caltech.edu>