The Gattini cameras are two site testing instruments for the measurement of optical sky brightnes... more The Gattini cameras are two site testing instruments for the measurement of optical sky brightness, large area cloud cover and auroral detection of the night sky above the high altitude Dome C site in Antarctica. The cameras have been in operation since January 2006. The cameras are transit in nature and are virtually identical, both adopting Apogee Alta ccd detectors. The camera called Gattini-SBC images a 6 degree field centred on the South Pole, an elevation of 75 o at the Dome C site. The camera takes repeated images of the same 6 degree field in the Sloan g' band (centred on 477nm) and, by adopting a lens with sufficiently long focal length, one can integrate the sky background photons and directly compare to the equivalent values of the stars within the field. The second camera, called Gattini-allsky, incorporates a fish-eye lens and images ~110 degree field centred on local zenith. By taking frequent images of the night sky we will obtain long term cloud cover statistics, measure the sky background intensity as a function of solar and lunar altitude and phase and directly measure the spatial extent of bright aurora if present and when they occur. An overview of the project is presented together with preliminary results from data taken since operation of the cameras in January 2006.
The Large Binocular Telescope (LBT) Project is a collaboration between institutions in Arizona, G... more The Large Binocular Telescope (LBT) Project is a collaboration between institutions in Arizona, Germany, Italy, and Ohio. The first of two 8.4-meter borosilicate honeycomb primary mirrors for LBT is being polished at the Steward Observatory Mirror Lab this year. The second of the two 8.4-meter mirror blanks waits its turn in the polishing queue. The baseline optical configuration of LBT includes adaptive infrared secondaries of a Gregorian design. The F/15 secondaries are undersized to provide a low thermal background focal plane which is unvignetted over a 4-arcminute diameter field-of-view. These adaptive secondary mirrors with 672 voice-coil actuators are now in the early stages of fabrication. The interferometric focus combining the light from the two 8.4-meter primaries will reimage the two folded Gregorian focal planes to three central locations for phased array imaging. The telescope elevation structure accommodates swing arm spiders which allow rapid interchange of the various secondary and tertiary mirrors as well as prime focus cameras. The telescope structure accommodates installation of a vacuum bell jar for aluminizing the primary mirrors in-situ on the telescope. The telescope structure was fabricated and pre-assembled in Italy by Ansaldo-Camozzi in Milan. The structure was disassembled, packed and shipped to Arizona. The enclosure was built on Mt. Graham and is ready for telescope installation.
The Large Binocular Telescope (LBT) Project is a collaboration between institutions in Arizona, G... more The Large Binocular Telescope (LBT) Project is a collaboration between institutions in Arizona, Germany, Italy, and Ohio. With the addition of the partners from Ohio State and Germany in February 1997, the Large Binocular Telescope Corporation has the funding required to build the full telescope populated with both 8.4 meter optical trans. The first of two 8.4 meter borosilicate honeycomb primary mirrors for LBT was cast at the Steward Observatory Mirror Lab in 1997. The baseline optical configuration of LBT includes adaptive infrared secondaries of a Gregorian design. The F/15 secondaries are undersized to provide a low thermal background focal plane. The interferometric focus combining the light from the two 8.4 meter primaries will reimage the two folded Gregorian focal planes to three central locations. The telescope elevation structure accommodates swing arms which allow rapid interchange of the various secondary and tertiary mirrors. Maximum stiffness and minimal thermal disturbance were important drivers for the design of the telescope in order to provide the best possible images for interferometric observations. The telescope structure accommodates installation of a vacuum bell jar for aluminizing the primary mirrors in-situ on the telescope. The detailed design of the telescope structure was completed in 1997 by ADS Italia (Lecco) and European Industrial Engineering (Mestre). A series of contracts for the fabrication and machining of the telescope structure had been placed at the end of 1997. The final enclosure design was completed at M3 Engineering & Technology (Tucson), EIE and ADS Italia. During 1997, the telescope pier and the concrete ring wall for the rotating enclosure were completed along with the steel structure of the fixed portion of the enclosure. The erection of the steel structure for the rotating portion of the enclosure will begin in the Spring of 1998.
On decrit un nouvel instrument permettant la detection du rayonnement millimetrique, monte sur le... more On decrit un nouvel instrument permettant la detection du rayonnement millimetrique, monte sur le telescope IR italien TIRGO
Fizeau interferometry at the Large Binocular Telescope (LBT) offers significant advantages over o... more Fizeau interferometry at the Large Binocular Telescope (LBT) offers significant advantages over other facilities in terms of spatial resolution, field of view, and sensitivity. We provide an update of the LINC-NIRVANA project, which aims to bring a near-infrared and visible wavelength Fizeau beam combiner to the LBT by late 2005. As with any complex instrument, a number of detailed requirements drive the final design adopted.
A cooled telescope for observation of the linear infrared cosmic background has been designed and... more A cooled telescope for observation of the linear infrared cosmic background has been designed and prepared for measurements in the waveband 1-5 microns at balloon altitudes (40 km). The detection system is based on an InSb linear array with 32 pixels placed in the focal plane of the telescope and thermally cryogenically controlled. A brief description is given of the
LINC-NIRVANA is a Fizeau interferometer which will be built for the Large Binocular Telescope (LB... more LINC-NIRVANA is a Fizeau interferometer which will be built for the Large Binocular Telescope (LBT). The LBT exists of two 8.4m mirrors on one mounting with a distance of 22.8m between the outer edges of the two mirrors. The interferometric technique used in LINC-NIRVANA provides direct imaging with the resolution of a 23m telescope in one direction and 8.4m in the other. The instrument uses multi-conjugated adaptive optics (MCAO) to increase the sky coverage and achieve the diffraction limit in J, H, K over a moderate Field of View (2 arcmin in diameter). During the preliminary design phase the team faced several problems similar to those for an instrument at a 23m telescope. We will give an overview ofthe current design, explain problems related to 20m class telescopes and present solutions.
Some of the new giant ground-bases telescopes will be equipped with interferometric systems, so t... more Some of the new giant ground-bases telescopes will be equipped with interferometric systems, so that multiple images of the same target, corresponding to different orientations of the baseline, will be available. These interferometric images will need specific processing to provide a unique high resolution image of the target. In this thesis we consider the case of the Large Binocular Telescope (LBT) which is currently under construction on the top of Mount Graham in Arizona and will be equipped with a Fizeau interferometer with a baseline of 22.8m. From the point of view of image reconstruction, the interesting feature is that LINC/NIRVANA (the Fizeau interferometer for LBT) will require routinely the use of multiple image deconvolution methods to produce a unique image with the resolution of a 22.8m telescope.
We describe the optical layout of the Large Binocular Telescope. Recent changes in the baseline o... more We describe the optical layout of the Large Binocular Telescope. Recent changes in the baseline optical configuration include moving the wide field foci above the primaries to allow a one degree field at F/4. The infrared F/15 secondaries are now a Gregorian design to allow maximum flexibility for adaptive optics. The F/15 secondaries are undersized to provide a low thermal background focal plane which is unvignetted over a 4 arcminute diameter field- of-view. The interferometric focus combining the light from the two 8.4 meter primaries will reimage two folded Gregorian focal planes to a central location. The telescope elevation structure accommodates swing arms which allow rapid interchange of the various secondary and tertiary mirrors. Using swing arms has allowed us to remove most of the superstructure supporting the spiders in an earlier version of the design. Maximum stiffness and minimal thermal disturbance continue to be important drivers for the detailed design of the telescope. By concentrating the structural mass between the two elevation C-rings, we are able to achieve a 2 Hz increase in the lowest eigenfrequency without increasing the mass of the elevation structure. The telescope structure accommodates installation of a vacuum bell jar for aluminizing the primary mirrors in-situ on the telescope. The detailed design of the telescope structure will be completed during 1994.
We discuss the current developments and the perspective performances of adaptive secondary mirror... more We discuss the current developments and the perspective performances of adaptive secondary mirrors for high order adaptive a correction on large ground based telescopes. The development of the basic techniques involved a large collaborative effort of public research Institutes and of private companies is now essentially complete. The next crucial step will be the construction of an adaptive secondary mirror for the 6.5 m MMT. Problems such as the fabrication of very thin mirrors, the low cost implementation of fast position sensors, of efficient and compact electromagnetic actuators, of the control and communication electronics, of the actuator control system, of the thermal control and of the mechanical layout can be considered as solved, in some cases with more than one viable solution. To verify performances at system level two complete prototypes have been built and tested, one at ThermoTrex and the other at Arcetri. The two prototypes adopt the same basic approach concerning actuators, sensor and support of the thin mirror, but differ in a number of aspects such as the material of the rigid back plate used as reference for the thin mirror, the number and surface density of the actuators, the solution adopted for the removal of the heat, and the design of the electronics. We discuss how the results obtained by of the two prototypes and by numerical simulations will guide the design of full size adaptive secondary units.
The Large Binocular Telescope (LBT) has been designed for optical/infrared interferometry that co... more The Large Binocular Telescope (LBT) has been designed for optical/infrared interferometry that combines high sensitivity and resolution. Key scientific projects will be deep, wide field infrared images of the Hubble Deep Field, with nearly ten times the resolution of the Hubble telescope, and the study of planets and dust in extra-solar systems, from their formation onward. A basic requirement for interferometry of faint objects is that the aberrations across the two 8.4 m telescopes be corrected for atmospheric phase errors. This will be done at the telescopes' secondary mirrors, so as to preserve the very low emissivity of the direct beam combination optics. Sodium lasers projected co-axially from above each secondary will allow wavefront sensing for correction of even the faintest objects. The two telescopes are rigidly mounted close together on a single alt-azimuth mount, to cover a large fraction of the u-v plane in a single exposure, with baselines continuous from 0 to 23 m. Field rotation during the night completes the cover, to allow recovery of images with the full resolution of a diffraction limited 23 m telescope. The beam combining optics will be cryogenically cooled to maintain the very low thermal background from only 3 warm reflections in total (primary, adaptive secondary, tertiary). For wide field imaging, the beams will be combined and stabilized so that in a long exposure every source across a ~ 1 arcminute field is crossed by interference fringes. From a set of such exposures the resultant deep image will have a resolution 0.02 arcsec in the 2.2µm K band. For high contrast studies of exo-planetary systems, a Bracewell nulling system will be used with superposition by division of amplitude, for 99.99% suppression of the stellar radiation.
The Large Binocular Telescope (LBT) Project is a collaboration between institutions in Arizona, G... more The Large Binocular Telescope (LBT) Project is a collaboration between institutions in Arizona, Germany, Italy, and Ohio. The telescope uses two 8.4-meter diameter primary mirrors mounted side-by-side to produce a collecting area equivalent to an 11.8-meter circular aperture. A unique feature of LBT is that the light from the two primary mirrors can be combined to produce phased array imaging of an extended field. This coherent imaging gives the telescope the diffraction-limited resolution of a 22.65-meter telescope. The first of two 8.4meter borosilicate honeycomb primary mirrors has been installed in the telescope on Mt. Graham in southeastern Arizona. First Light is planned for later this year with one primary mirror and a prime focus imager. The second of the two primaries is being polished at the Steward Observatory Mirror Lab in Tucson and will be installed in the telescope in the Fall of 2005. The telescope uses two F/15 adaptive secondaries to correct atmospheric turbulence.
The Gattini cameras are two site testing instruments for the measurement of optical sky brightnes... more The Gattini cameras are two site testing instruments for the measurement of optical sky brightness, large area cloud cover and auroral detection of the night sky above the high altitude Dome C site in Antarctica. The cameras have been in operation since January 2006. The cameras are transit in nature and are virtually identical, both adopting Apogee Alta ccd detectors. The camera called Gattini-SBC images a 6 degree field centred on the South Pole, an elevation of 75 o at the Dome C site. The camera takes repeated images of the same 6 degree field in the Sloan g' band (centred on 477nm) and, by adopting a lens with sufficiently long focal length, one can integrate the sky background photons and directly compare to the equivalent values of the stars within the field. The second camera, called Gattini-allsky, incorporates a fish-eye lens and images ~110 degree field centred on local zenith. By taking frequent images of the night sky we will obtain long term cloud cover statistics, measure the sky background intensity as a function of solar and lunar altitude and phase and directly measure the spatial extent of bright aurora if present and when they occur. An overview of the project is presented together with preliminary results from data taken since operation of the cameras in January 2006.
The Large Binocular Telescope (LBT) Project is a collaboration between institutions in Arizona, G... more The Large Binocular Telescope (LBT) Project is a collaboration between institutions in Arizona, Germany, Italy, and Ohio. The first of two 8.4-meter borosilicate honeycomb primary mirrors for LBT is being polished at the Steward Observatory Mirror Lab this year. The second of the two 8.4-meter mirror blanks waits its turn in the polishing queue. The baseline optical configuration of LBT includes adaptive infrared secondaries of a Gregorian design. The F/15 secondaries are undersized to provide a low thermal background focal plane which is unvignetted over a 4-arcminute diameter field-of-view. These adaptive secondary mirrors with 672 voice-coil actuators are now in the early stages of fabrication. The interferometric focus combining the light from the two 8.4-meter primaries will reimage the two folded Gregorian focal planes to three central locations for phased array imaging. The telescope elevation structure accommodates swing arm spiders which allow rapid interchange of the various secondary and tertiary mirrors as well as prime focus cameras. The telescope structure accommodates installation of a vacuum bell jar for aluminizing the primary mirrors in-situ on the telescope. The telescope structure was fabricated and pre-assembled in Italy by Ansaldo-Camozzi in Milan. The structure was disassembled, packed and shipped to Arizona. The enclosure was built on Mt. Graham and is ready for telescope installation.
The Large Binocular Telescope (LBT) Project is a collaboration between institutions in Arizona, G... more The Large Binocular Telescope (LBT) Project is a collaboration between institutions in Arizona, Germany, Italy, and Ohio. With the addition of the partners from Ohio State and Germany in February 1997, the Large Binocular Telescope Corporation has the funding required to build the full telescope populated with both 8.4 meter optical trans. The first of two 8.4 meter borosilicate honeycomb primary mirrors for LBT was cast at the Steward Observatory Mirror Lab in 1997. The baseline optical configuration of LBT includes adaptive infrared secondaries of a Gregorian design. The F/15 secondaries are undersized to provide a low thermal background focal plane. The interferometric focus combining the light from the two 8.4 meter primaries will reimage the two folded Gregorian focal planes to three central locations. The telescope elevation structure accommodates swing arms which allow rapid interchange of the various secondary and tertiary mirrors. Maximum stiffness and minimal thermal disturbance were important drivers for the design of the telescope in order to provide the best possible images for interferometric observations. The telescope structure accommodates installation of a vacuum bell jar for aluminizing the primary mirrors in-situ on the telescope. The detailed design of the telescope structure was completed in 1997 by ADS Italia (Lecco) and European Industrial Engineering (Mestre). A series of contracts for the fabrication and machining of the telescope structure had been placed at the end of 1997. The final enclosure design was completed at M3 Engineering & Technology (Tucson), EIE and ADS Italia. During 1997, the telescope pier and the concrete ring wall for the rotating enclosure were completed along with the steel structure of the fixed portion of the enclosure. The erection of the steel structure for the rotating portion of the enclosure will begin in the Spring of 1998.
On decrit un nouvel instrument permettant la detection du rayonnement millimetrique, monte sur le... more On decrit un nouvel instrument permettant la detection du rayonnement millimetrique, monte sur le telescope IR italien TIRGO
Fizeau interferometry at the Large Binocular Telescope (LBT) offers significant advantages over o... more Fizeau interferometry at the Large Binocular Telescope (LBT) offers significant advantages over other facilities in terms of spatial resolution, field of view, and sensitivity. We provide an update of the LINC-NIRVANA project, which aims to bring a near-infrared and visible wavelength Fizeau beam combiner to the LBT by late 2005. As with any complex instrument, a number of detailed requirements drive the final design adopted.
A cooled telescope for observation of the linear infrared cosmic background has been designed and... more A cooled telescope for observation of the linear infrared cosmic background has been designed and prepared for measurements in the waveband 1-5 microns at balloon altitudes (40 km). The detection system is based on an InSb linear array with 32 pixels placed in the focal plane of the telescope and thermally cryogenically controlled. A brief description is given of the
LINC-NIRVANA is a Fizeau interferometer which will be built for the Large Binocular Telescope (LB... more LINC-NIRVANA is a Fizeau interferometer which will be built for the Large Binocular Telescope (LBT). The LBT exists of two 8.4m mirrors on one mounting with a distance of 22.8m between the outer edges of the two mirrors. The interferometric technique used in LINC-NIRVANA provides direct imaging with the resolution of a 23m telescope in one direction and 8.4m in the other. The instrument uses multi-conjugated adaptive optics (MCAO) to increase the sky coverage and achieve the diffraction limit in J, H, K over a moderate Field of View (2 arcmin in diameter). During the preliminary design phase the team faced several problems similar to those for an instrument at a 23m telescope. We will give an overview ofthe current design, explain problems related to 20m class telescopes and present solutions.
Some of the new giant ground-bases telescopes will be equipped with interferometric systems, so t... more Some of the new giant ground-bases telescopes will be equipped with interferometric systems, so that multiple images of the same target, corresponding to different orientations of the baseline, will be available. These interferometric images will need specific processing to provide a unique high resolution image of the target. In this thesis we consider the case of the Large Binocular Telescope (LBT) which is currently under construction on the top of Mount Graham in Arizona and will be equipped with a Fizeau interferometer with a baseline of 22.8m. From the point of view of image reconstruction, the interesting feature is that LINC/NIRVANA (the Fizeau interferometer for LBT) will require routinely the use of multiple image deconvolution methods to produce a unique image with the resolution of a 22.8m telescope.
We describe the optical layout of the Large Binocular Telescope. Recent changes in the baseline o... more We describe the optical layout of the Large Binocular Telescope. Recent changes in the baseline optical configuration include moving the wide field foci above the primaries to allow a one degree field at F/4. The infrared F/15 secondaries are now a Gregorian design to allow maximum flexibility for adaptive optics. The F/15 secondaries are undersized to provide a low thermal background focal plane which is unvignetted over a 4 arcminute diameter field- of-view. The interferometric focus combining the light from the two 8.4 meter primaries will reimage two folded Gregorian focal planes to a central location. The telescope elevation structure accommodates swing arms which allow rapid interchange of the various secondary and tertiary mirrors. Using swing arms has allowed us to remove most of the superstructure supporting the spiders in an earlier version of the design. Maximum stiffness and minimal thermal disturbance continue to be important drivers for the detailed design of the telescope. By concentrating the structural mass between the two elevation C-rings, we are able to achieve a 2 Hz increase in the lowest eigenfrequency without increasing the mass of the elevation structure. The telescope structure accommodates installation of a vacuum bell jar for aluminizing the primary mirrors in-situ on the telescope. The detailed design of the telescope structure will be completed during 1994.
We discuss the current developments and the perspective performances of adaptive secondary mirror... more We discuss the current developments and the perspective performances of adaptive secondary mirrors for high order adaptive a correction on large ground based telescopes. The development of the basic techniques involved a large collaborative effort of public research Institutes and of private companies is now essentially complete. The next crucial step will be the construction of an adaptive secondary mirror for the 6.5 m MMT. Problems such as the fabrication of very thin mirrors, the low cost implementation of fast position sensors, of efficient and compact electromagnetic actuators, of the control and communication electronics, of the actuator control system, of the thermal control and of the mechanical layout can be considered as solved, in some cases with more than one viable solution. To verify performances at system level two complete prototypes have been built and tested, one at ThermoTrex and the other at Arcetri. The two prototypes adopt the same basic approach concerning actuators, sensor and support of the thin mirror, but differ in a number of aspects such as the material of the rigid back plate used as reference for the thin mirror, the number and surface density of the actuators, the solution adopted for the removal of the heat, and the design of the electronics. We discuss how the results obtained by of the two prototypes and by numerical simulations will guide the design of full size adaptive secondary units.
The Large Binocular Telescope (LBT) has been designed for optical/infrared interferometry that co... more The Large Binocular Telescope (LBT) has been designed for optical/infrared interferometry that combines high sensitivity and resolution. Key scientific projects will be deep, wide field infrared images of the Hubble Deep Field, with nearly ten times the resolution of the Hubble telescope, and the study of planets and dust in extra-solar systems, from their formation onward. A basic requirement for interferometry of faint objects is that the aberrations across the two 8.4 m telescopes be corrected for atmospheric phase errors. This will be done at the telescopes' secondary mirrors, so as to preserve the very low emissivity of the direct beam combination optics. Sodium lasers projected co-axially from above each secondary will allow wavefront sensing for correction of even the faintest objects. The two telescopes are rigidly mounted close together on a single alt-azimuth mount, to cover a large fraction of the u-v plane in a single exposure, with baselines continuous from 0 to 23 m. Field rotation during the night completes the cover, to allow recovery of images with the full resolution of a diffraction limited 23 m telescope. The beam combining optics will be cryogenically cooled to maintain the very low thermal background from only 3 warm reflections in total (primary, adaptive secondary, tertiary). For wide field imaging, the beams will be combined and stabilized so that in a long exposure every source across a ~ 1 arcminute field is crossed by interference fringes. From a set of such exposures the resultant deep image will have a resolution 0.02 arcsec in the 2.2µm K band. For high contrast studies of exo-planetary systems, a Bracewell nulling system will be used with superposition by division of amplitude, for 99.99% suppression of the stellar radiation.
The Large Binocular Telescope (LBT) Project is a collaboration between institutions in Arizona, G... more The Large Binocular Telescope (LBT) Project is a collaboration between institutions in Arizona, Germany, Italy, and Ohio. The telescope uses two 8.4-meter diameter primary mirrors mounted side-by-side to produce a collecting area equivalent to an 11.8-meter circular aperture. A unique feature of LBT is that the light from the two primary mirrors can be combined to produce phased array imaging of an extended field. This coherent imaging gives the telescope the diffraction-limited resolution of a 22.65-meter telescope. The first of two 8.4meter borosilicate honeycomb primary mirrors has been installed in the telescope on Mt. Graham in southeastern Arizona. First Light is planned for later this year with one primary mirror and a prime focus imager. The second of the two primaries is being polished at the Steward Observatory Mirror Lab in Tucson and will be installed in the telescope in the Fall of 2005. The telescope uses two F/15 adaptive secondaries to correct atmospheric turbulence.
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Papers by Piero Salinari