The Sloan Digital Sky Survey 2.5-m telescope is unique with a 3 degree(s) field of view at f/5. T... more The Sloan Digital Sky Survey 2.5-m telescope is unique with a 3 degree(s) field of view at f/5. The two-mirror optical design includes two transmitting correcting elements. To avoid excessive central obstruction of the entrance pupil, a conical baffle is necessary in addition to the usual primary and secondary baffles. This conical baffle is suspended approximately midway between the primary
The NASA IRTF is arguably the only ground-based telescope in the world dedicated to planetary ast... more The NASA IRTF is arguably the only ground-based telescope in the world dedicated to planetary astronomy. Two decades of improvement in infrared array technology, adaptive optics, and large mirror fabrication techniques now make it imperative that the future needs of NASA's Planetary Astronomy program be considered in the context of the capabilities now possible for a modern telescope. In response to a suggestion from NASA Headquarters we have developed an innovative telescope concept which provides unique and unsurpassed scientific capabilities to the planetary community. We call this facility the New Planetary Telescope (NPT). We have assumed that the main objectives for the NPT are studies of Kuiper Belt Objects, Near-Earth Objects, studies of circumstellar disks and extra-solar planets, and ground-based support for NASA flight missions. These diverse scientific objectives require capabilities ranging over wide-field imaging, high angular resolution, high sensitivity in the optical and thermal infrared, and superb photometric dynamic range. This study shows that it is possible to achieve all of these performance requirements using a 6.5m unobstructed, off-axis telescope. This concept has compelling natural advantages for adaptive optics, coronagraphic astronomical imaging, and thermal infrared imaging. Unique features of the NPT include wide-field imaging capability, with a field-of-view of at least two degrees, optimization for unprecedented low scattered light and high dynamic range astronomy, extremely low infrared emissivity, and innovative instruments uniquely designed to take full advantage of these capabilities. This telescope concept breaks new ground in telescope technology, and it is therefore an ideal technical development project for NASA. NASA is currently at the forefront of development in interferometry using the Keck telescopes. The NPT complements and enhances this program since it provides an important baseline to add to those already planned on Mauna Kea. Moreover, the NPT is the ideal telescope for a full-fledged optical/infrared array of interferometric telescopes.
ABSTRACT The preliminary design of the 25 m Giant Magellan Telescope (GMT) has been completed. Th... more ABSTRACT The preliminary design of the 25 m Giant Magellan Telescope (GMT) has been completed. This paper describes the design of the optics, structure and mechanisms, together with the rationales that lead to the current design. Analyses that were conducted to verify structure and optical performance are summarized. Science instruments will be mounted within the telescope structure. A common instrument de-rotator is provided to compensate for field rotation caused by the alt-az tracking of the telescope. The various instrument stations and provisions for mounting instruments are described. Post-PDR development plans for the telescope are presented.
... Magellan Telescope Michael Sheehan* a , Steve Gunnels b , Charles Hull a , Jonathan Kern a , ... more ... Magellan Telescope Michael Sheehan* a , Steve Gunnels b , Charles Hull a , Jonathan Kern a , Carey Smith a , Matt Johns a , ... The cells are additionally connected through a cell connector frame (CCF) consisting of a central hexagonal hub and 6 spokes. ...
The magnetic cataclysmic variable AE Aquarii hosts a rapidly rotating white dwarf which is though... more The magnetic cataclysmic variable AE Aquarii hosts a rapidly rotating white dwarf which is thought to expel most of the material streaming onto it. Observations of AE Aqr have been obtained in the wavelength range of 5 - 70 microns with the IRS, IRAC, and MIPS instruments on board the Spitzer Space Telescope. The spectral energy distribution reveals a significant excess above the K4V spectrum of the donor star with the flux increasing with wavelength above 12.5 microns. Superposed on the energy distribution are several hydrogen emission lines, identified as Pf alpha and Hu alpha, beta, gamma. The infrared spectrum above 12.5 microns can be interpreted as synchrotron emission from electrons accelerated to a power-law distribution dN=E^{-2.4}dE in expanding clouds with an initial evolution timescale in seconds. However, too many components must then be superposed to explain satisfactorily both the mid-infrared continuum and the observed radio variability. Thermal emission from cold circumbinary material can contribute, but it requires a disk temperature profile intermediate between that produced by local viscous dissipation in the disk and that characteristic of a passively irradiated disk. Future high-time resolution observations spanning the optical to radio regime could shed light on the acceleration process and the subsequent particle evolution.
Ground-based and Airborne Instrumentation for Astronomy IV, 2012
ABSTRACT The f/5 instrumentation suite for the Clay telescope was developed to provide the Magell... more ABSTRACT The f/5 instrumentation suite for the Clay telescope was developed to provide the Magellan Consortium observer community with wide field optical imaging and multislit NIR spectroscopy capability. The instrument suite consists of several major subsystems including two focal plane instruments. These instruments are Megacam and MMIRS. Megacam is a panoramic, square format CCD mosaic imager, 0.4° on a side. It is instrumented with a full set of Sloan filters. MMIRS is a multislit NIR spectrograph that operates in Y through K band and has long slit and imaging capability as well. These two instruments can operate both at Magellan and the MMT. Megacam requires a wide field refractive corrector and a Topbox to support shutter and filter selection functions, as well as to perform wavefront sensing for primary mirror figure correction. Both the corrector and Topbox designs were modeled on previous designs for MMT, however features of the Magellan telescope required considerable revision of these designs. In this paper we discuss the optomechanical, electrical, software and structural design of these subsystems, as well as operational considerations that attended delivery of the instrument suite to first light.
Survey and Other Telescope Technologies and Discoveries, 2002
The support and position control systems for both the primary and secondary mirror of the SDSS Te... more The support and position control systems for both the primary and secondary mirror of the SDSS Telescope allow the mirrors up to 12 mm of precisely positioned axial motion, as well as limited tilt and transverse motion. This paper describes the final design and operation of these systems. Some relative strengths and limitations of the components and problems encountered with
The Sloan Digital Sky Survey 2.5-m telescope is unique with a 3 degree(s) field of view at f/5. T... more The Sloan Digital Sky Survey 2.5-m telescope is unique with a 3 degree(s) field of view at f/5. The two-mirror optical design includes two transmitting correcting elements. To avoid excessive central obstruction of the entrance pupil, a conical baffle is necessary in addition to the usual primary and secondary baffles. This conical baffle is suspended approximately midway between the primary
The NASA IRTF is arguably the only ground-based telescope in the world dedicated to planetary ast... more The NASA IRTF is arguably the only ground-based telescope in the world dedicated to planetary astronomy. Two decades of improvement in infrared array technology, adaptive optics, and large mirror fabrication techniques now make it imperative that the future needs of NASA's Planetary Astronomy program be considered in the context of the capabilities now possible for a modern telescope. In response to a suggestion from NASA Headquarters we have developed an innovative telescope concept which provides unique and unsurpassed scientific capabilities to the planetary community. We call this facility the New Planetary Telescope (NPT). We have assumed that the main objectives for the NPT are studies of Kuiper Belt Objects, Near-Earth Objects, studies of circumstellar disks and extra-solar planets, and ground-based support for NASA flight missions. These diverse scientific objectives require capabilities ranging over wide-field imaging, high angular resolution, high sensitivity in the optical and thermal infrared, and superb photometric dynamic range. This study shows that it is possible to achieve all of these performance requirements using a 6.5m unobstructed, off-axis telescope. This concept has compelling natural advantages for adaptive optics, coronagraphic astronomical imaging, and thermal infrared imaging. Unique features of the NPT include wide-field imaging capability, with a field-of-view of at least two degrees, optimization for unprecedented low scattered light and high dynamic range astronomy, extremely low infrared emissivity, and innovative instruments uniquely designed to take full advantage of these capabilities. This telescope concept breaks new ground in telescope technology, and it is therefore an ideal technical development project for NASA. NASA is currently at the forefront of development in interferometry using the Keck telescopes. The NPT complements and enhances this program since it provides an important baseline to add to those already planned on Mauna Kea. Moreover, the NPT is the ideal telescope for a full-fledged optical/infrared array of interferometric telescopes.
ABSTRACT The preliminary design of the 25 m Giant Magellan Telescope (GMT) has been completed. Th... more ABSTRACT The preliminary design of the 25 m Giant Magellan Telescope (GMT) has been completed. This paper describes the design of the optics, structure and mechanisms, together with the rationales that lead to the current design. Analyses that were conducted to verify structure and optical performance are summarized. Science instruments will be mounted within the telescope structure. A common instrument de-rotator is provided to compensate for field rotation caused by the alt-az tracking of the telescope. The various instrument stations and provisions for mounting instruments are described. Post-PDR development plans for the telescope are presented.
... Magellan Telescope Michael Sheehan* a , Steve Gunnels b , Charles Hull a , Jonathan Kern a , ... more ... Magellan Telescope Michael Sheehan* a , Steve Gunnels b , Charles Hull a , Jonathan Kern a , Carey Smith a , Matt Johns a , ... The cells are additionally connected through a cell connector frame (CCF) consisting of a central hexagonal hub and 6 spokes. ...
The magnetic cataclysmic variable AE Aquarii hosts a rapidly rotating white dwarf which is though... more The magnetic cataclysmic variable AE Aquarii hosts a rapidly rotating white dwarf which is thought to expel most of the material streaming onto it. Observations of AE Aqr have been obtained in the wavelength range of 5 - 70 microns with the IRS, IRAC, and MIPS instruments on board the Spitzer Space Telescope. The spectral energy distribution reveals a significant excess above the K4V spectrum of the donor star with the flux increasing with wavelength above 12.5 microns. Superposed on the energy distribution are several hydrogen emission lines, identified as Pf alpha and Hu alpha, beta, gamma. The infrared spectrum above 12.5 microns can be interpreted as synchrotron emission from electrons accelerated to a power-law distribution dN=E^{-2.4}dE in expanding clouds with an initial evolution timescale in seconds. However, too many components must then be superposed to explain satisfactorily both the mid-infrared continuum and the observed radio variability. Thermal emission from cold circumbinary material can contribute, but it requires a disk temperature profile intermediate between that produced by local viscous dissipation in the disk and that characteristic of a passively irradiated disk. Future high-time resolution observations spanning the optical to radio regime could shed light on the acceleration process and the subsequent particle evolution.
Ground-based and Airborne Instrumentation for Astronomy IV, 2012
ABSTRACT The f/5 instrumentation suite for the Clay telescope was developed to provide the Magell... more ABSTRACT The f/5 instrumentation suite for the Clay telescope was developed to provide the Magellan Consortium observer community with wide field optical imaging and multislit NIR spectroscopy capability. The instrument suite consists of several major subsystems including two focal plane instruments. These instruments are Megacam and MMIRS. Megacam is a panoramic, square format CCD mosaic imager, 0.4° on a side. It is instrumented with a full set of Sloan filters. MMIRS is a multislit NIR spectrograph that operates in Y through K band and has long slit and imaging capability as well. These two instruments can operate both at Magellan and the MMT. Megacam requires a wide field refractive corrector and a Topbox to support shutter and filter selection functions, as well as to perform wavefront sensing for primary mirror figure correction. Both the corrector and Topbox designs were modeled on previous designs for MMT, however features of the Magellan telescope required considerable revision of these designs. In this paper we discuss the optomechanical, electrical, software and structural design of these subsystems, as well as operational considerations that attended delivery of the instrument suite to first light.
Survey and Other Telescope Technologies and Discoveries, 2002
The support and position control systems for both the primary and secondary mirror of the SDSS Te... more The support and position control systems for both the primary and secondary mirror of the SDSS Telescope allow the mirrors up to 12 mm of precisely positioned axial motion, as well as limited tilt and transverse motion. This paper describes the final design and operation of these systems. Some relative strengths and limitations of the components and problems encountered with
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Papers by Charles Hull