First Light of the Hobby*Eberly Telescope Low-Resolution Spectrograph (LRS)
A joint release from The University of Texas at Austin, Pennsylvania State University (Penn State), Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen
The Hobby*Eberly Telescope Consortium is pleased to announce the first light of the Marcario Low-Resolution Spectrograph (LRS). The Marcario LRS is the first facility-class instrument to be delivered for the Hobby*Eberly Telescope (HET), which is the third largest telescope in the world.
The HET is a unique optical telescope located on Mount Fowlkes at McDonald Observatory in West Texas. The primary mirror is 11 meters across and consists of 91 spherically figured segments. The telescope is fixed in elevation but movable in azimuth, and stars are followed across the sky by a tracker atop the telescope's frame. Because of this design, the HET was built for a fraction of the cost of a conventional telescope of its size.
The strengths of the HET will be in conducting large spectroscopic surveys and in observations of time-variable phenomena and targets of opportunity, such as newly discovered supernovae.
The Marcario spectrograph is designed to observe very faint astronomical objects. It is an imaging spectrograph with rapid reconfiguration, giving maximum flexibility to respond to the observing program of the telescope, which will be queue-scheduled.
The first-light observations of the HET with the Marcario LRS, obtained in April 1999, illustrate these capabilities and indicate that the performance goals of the instrument are being realized.
One of the first observations of the Marcario LRS was of a distant quasar candidate that had been identified earlier in commissioning data of the Sloan Digital Sky Survey (SDSS).
The SDSS will image one-quarter of the sky in five different filters. In the next few years, this database will allow the identification of approximately 100,000 quasars, which compares with the fewer than 20,000 quasars that have been discovered in more than 35 years since the first quasar was found. Quasars are very luminous objects that are thought to be powered by supermassive black holes at the centers of galaxies.
The first scientific spectrum produced by the HET. Shown are three of the spectral features used to determine the redshift of this distant SDSS quasar.
On April 23, 1999, the HET and the Marcario LRS confirmed that one of the SDSS quasar candidates was indeed a quasar residing approximately 10 billion light-years from Earth. The light gathered to capture the spectrum left this quasar when the universe was only one-eighth as old as it is today.
Another observation with the HET and the Marcario LRS illustrates the important role that the HET will play in responding to new time-critical opportunities, and in monitoring time-variable phenomena.
This was actually the first observation obtained by the new instrument, two days before identification of the SDSS quasar. It involved capturing the spectrum of supernova 1999bv.
This supernova was observed 2 days after its discovery, and the spectrum allowed it to be confirmed and classified. As this supernova fades beyond the reach of smaller telescopes, the HET will be able to follow its evolution in a systematic manner.
Further observations over the next few months will be used to characterize and commission the Marcario LRS, and the observing communities of the HET partners are looking forward to realizing the great scientific promise of this instrument.
LRS CCD detector cryostat. The CCD is housed in the small head at the end of the black arm, and is inserted into the side of the f/1.4 camera.
A consortium of five institutions built and operates the HET: The University of Texas at Austin; The Pennsylvania State University (Penn State); Stanford University; Ludwig- Maximilians-Universität, Munich, Germany; and Georg-August-Universität, Göttingen, Germany.
The Marcario LRS was built by an international consortium of institutions under the direction of Dr. Gary J. Hill of The University of Texas at Austin McDonald Observatory. It utilizes a state-of-the-art CCD system built by Dr. Phillip MacQueen, also of McDonald Observatory. The project combined expertise from The University of Texas at Austin; Ludwig-Maximilians-Universität, Munich, Germany; Georg-August-Universität, Göttingen, Germany; the Instituto de Astronomí a de la Universidad Nacional Autónoma de México (IAUNAM); Stanford University; and Pennsylvania State University (Penn State). The optics of the LRS were designed and six of the lenses were figured by experts at IAUNAM. The spectrograph is named for Mike Marcario of High Lonesome Optics in West Texas, who produced superb lenses for the spectrograph but died tragically before its completion.
Two other facility-class spectrographs will be later be added to the Hobby*Eberly Telescope. A Medium-Resolution Spectrograph is being constructed at Pennsylvania State University (Penn State), under the direction of HET project scientist Dr. Larry Ramsey. A High-Resolution Spectrograph is being constructed at the University of Texas at Austin under the direction of Dr. Robert Tull. These instruments will enable more detailed study of objects in and near the Milky Way.
For additional information on the HET or the Marcario Spectrograph
Dr. Gary Hill - University of Texas at Austin
phone: (512) 471-1477
For additional information on Sloan Survey targets or the Medium Resolution Spectrograph
Barbara K. Kennedy - Pennsylvania State University
The Hobby*Eberly Telescope: A joint project of The University of Texas at Austin, Pennsylvania State University (Penn State), Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen