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G. J. Hill (McDonald Observatory, University of Texas at Austin)
The Hobby-Eberly Telescope (HET) is a revolutionary large telescope of 9.2 meter aperture, located in West Texas at McDonald Observatory. HET is a collaboration of the University of Texas at Austin, Pennsylvania State University, Stanford University, Georg-August-Universität, Göttingen, and Ludwig-Maximillians-Universität, München. The telescope was dedicated on Oct. 8, 1997, and will enter science operations in 1999. The US community will have several weeks per year of queue-scheduled nights on the HET via National Science Foundation support of instrumentation.
The HET is a unique telescope with an 11 m hexagonal-shaped spherical mirror made of 91 segments that sits at a fixed zenith distance of 35o. It can be moved in azimuth to access about 70% of the sky visible at McDonald Observatory. The pupil is 9.2 m and sweeps over the primary as the x-y tracker follows objects for between 40 minutes (in the south at \delta=-10.3o) and 2.8 hours (in the north at \delta=+71.6o). The maximum track time per night is 5 hours and occurs at \delta~63o. The effective aperture for these track times is 8 m.
Three facility instruments are under construction. The High Resolution and Medium Resolution Spectrographs will reside in the basement instrument room and will be fed by fibers. The Low Resolution Spectrograph (LRS) rides on the HET tracker at prime focus. The LRS is virtually complete and will see first light in early 1999.
The HET is a special-purpose instrument aimed primarily at science requiring spectroscopic observations over a relatively small field of view (4 arcmin.). It will be used in a different manner to the other large telescopes. The principal niches of the HET will be large surveys and temporal phenomena, taking advantage of its aperture and queue-scheduling. Studies involving large samples and long-term monitoring are likely to be emphasized over intensive work on small numbers of very faint objects. It will be possible to build up signal-to-noise (S/N) ratio through repeated visits to the same targets.
Groundwork has been underway for several years on projects to assemble samples of objects for HET, and the telescope is also ideally suited for follow-up of extensive surveys such as SDSS and FIRST. We will discuss examples of science that will be pursued with the HET. These examples are chosen to illustrate the areas of astronomy where the HET has particular application, or has a niche. Projects which benefit from the queue-scheduling include studies of periodic phenomena (extrasolar planets, variable stars), transient phenomena (supernovae, soft X-ray transients), and monitoring (AGN echo mapping). Projects which require the aperture to observe large samples at appropriate S/N include structure and abundance mapping of the Galactic halo, confirmation of high redshift QSOs discovered in new surveys, mapping large-scale structure at high redshift, and studies of the evolution of galaxies in clusters. A subset of these projects will be explored in detail to illustrate the capabilities of the HET.
As the HET enters its first year of scientific operations we look forward to initiating observing programs aimed at significantly increasing our knowledge in several areas of astronomy.
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