Gilberto Moretto

First results from the NSO/NJIT solar adaptive optics system

The National Solar Observatory and the New Jersey Institute of Technology have developed two 97 actuator solar adaptive optics (AO) systems based on a correlating Shack-Hartmann wavefront sensor approach. The first engineering run was successfully completed at the Dunn Solar Telescope (DST) at Sacramento Peak, New Mexico in December 2002. The first of two systems is now operational at Sacramento Peak. The second system will be deployed at the Big Bear Solar Observatory by the end of 2003. The correlating Shack-Hartmann wavefront sensor is able to measure wavefront aberrations for low-contrast, extended and time-varying objects, such as solar granulation. The 97-actuator solar AO system operates at a loop update rate of 2.5 kHz and achieves a closed loop bandwidth (0dB crossover error rejection) of about 130 Hz. The AO system is capable of correcting atmospheric seeing at visible wavelengths during median seeing conditions at both the NSO/Sacramento Peak site and the Big Bear Solar Observatory. We present an overview of the system design. The servo loop was successfully closed and first AO corrected images were recorded. We present first results from the new, high order AO system.

Instrumentation for the Advanced Technology Solar Telescope

The 4-m aperture Advanced Technology Solar Telescope (ATST) is the next generation ground based solar telescope. In this paper we provide an overview of the ATST post-focus instrumentation. The majority of ATST instrumentation is located in an instrument Coude lab facility, where a rotating platform provides image de-rotation. A high order adaptive optics system delivers a corrected beam to the Coude lab facility. Alternatively, instruments can be mounted at Nasmyth or a small Gregorian area. For example, instruments for observing the faint corona preferably will be mounted at Nasmyth focus where maximum throughput is achieved. In addition, the Nasmyth focus has minimum telescope polarization and minimum stray light. We describe the set of first generation instruments, which include a Visible-Light Broadband Imager (VLBI), Visible and Near-Infrared (NIR) Spectropolarimeters, Visible and NIR Tunable Filters, a Thermal-Infrared Polarimeter & Spectrometer and a UV-Polarimeter. We also discuss unique and efficient approaches to the ATST instrumentation, which builds on the use of common components such as detector systems, polarimetry packages and various opto-mechanical components.

Corrector design with active vase mirrors that allows a fixed telescope to access a large region of the sky

We investigate a family of two-mirror correctors to compensate for the aberrations of a parabolic mirror observing at a large angle from the zenith. We constrain our designs to optical elements that can be built with currently available technology. The secondary and the tertiary mirrors are warped by Zernike polynomials, which we know can be generated with active vase mirrors. The performances of these corrector designs are usable for imagery.

Wide Field Astronomy at Dome C: two IR Surveys Complementary to SNAP

Surveys provide a wealth of data to the astronomical community that are used well after their completion. In this paper, we propose a project that would take the maximum benefit of Dome C in Antarctica by performing two surveys, in the wavelength range from 1-5 micron, complementary to SNAP space surveys. The first one over 1000 sq. deg. (1 KdF) for 4 years and the second one over 15 sq. deg (SNAP-IR) for the next 4 years at the same time as SNAP 0.35-1.7 microns survey. By using a Ground-Layer Adaptive Optics system, we would be able to recover, at the ice level and over at least half a degree in radius, the 300 mas angular resolution available above the 30-m high turbulent layer. Such a survey, combining a high angular resolution with high sensitivities in the NIR and MIR, should also play the role of a pre-survey for JWST and ALMA.

Optical design for a Fabry-Perot image interferometer for solar observations

We outline here a preliminary optical design study for a telecentric tunable Fabry-Perot etalon system. The first result of the optical optimization into a design, which delivers performance image quality and telecentricity, is presented here. Bearing in mind the possible use of such a study design - as a possible instrument for the Advanced Technology Solar Telescope (ATST) - we also show that a hybrid design strategy delivers a compact design that will fit inside the ATSTs Coude optical tables.

Optical design of a 6.5-m off-axis new planetary telescope

We describe here an off-axis design for a 6.5 m astronomical telescope optimized for low scattered light and low emissivity. This is part of a new concept for an instrument which we call the New Planetary Telescope. We show how the geometric optical performance can equal that of an on-axis conventional telescope while the diffractive performance fundamentally surpasses conventional telescopes because of the absence of pupil obstruction. The decentered concept also allows wide-field and versatile instrumentation configurations that are not possible with more conventional design.

SOAR Telescope Project: a four-meter telescope focused on image quality

Side effects of an aminoglycoside antibiotic, renal toxicity and 8th nerve toxicity, are reduced by administering a glucosaccharic acid as well as the aminoglycoside antibiotic. An improved method for treating bacterial infection using an aminoglycoside antibiotic and a pharmaceutical composition of an aminoglycoside antibiotic with reduced side effects are disclosed.

Multi-Conjugate Adaptive Optics - relay optical designs for a 4-m off-axis solar telescope

The Sun is an ideal object for the development and application of Multi-Conjugate Adaptive Optics (MCAO). An effort to develop solar MCAO is pursued by the NSO’s Adaptive Optics Project. In developing solar MCAO we bear in mind its possible implementation into the proposed 4-M Advanced Technology Solar Telescope (ATST). Two possible relay optical designs feeding a MCAO section and the Coudé section of a 4-M off-axis solar telescope, such as the proposed ATST, are presented and discussed here.

Three-dimensional high-order wavefront sensing, anisoplanatism, and evaluation of the feasibility of solar MCAO

Multiconjugate adaptive optics has been proposed in order to extend the size of the corrected field of view with respect to the classical AO field of view. In order to achieve this, a three dimensional measurement of the turbulent volume is needed to collect the information to command the several deformable mirrors. This can be done by using tomography, in which several WFS are used, each of them coupled to a sky region. Here we report the experimental demonstration of such evaluation for solar observations. In addition, we confront these results on turbulence distribution with a study of AO corrected images by using multi point large field of view wavefront sensing with the new Dunn Solar Telescope adaptive optics system. This yields to information on the AO system performances and provide useful estimate of the PSF variation across the field. The results from this article provides an important step forward for building a full solar multi-conjugate adaptive optics system for the Dunn Solar Telescope and in a longer term for the future 4 meter ATST telescope.

NPT: a large-aperture telescope for high dynamic range astronomy

All existing night-time astronomical telescopes, regardless of aperture, are blind to an important part of the universe - the region around bright objects. Technology now exist to build an unobscured 6.5 m aperture telescope which will attain coronagraphic sensitivity heretofore unachieved. A working group hosted by the University of Hawaii Institute for Astronomy has developed plans for a New Planetary Telescope which will permit astronomical observations which have never before ben possible. In its narrow-field mode the off-axis optical design, combined with adaptive optics, provides superb coronagraphic capabilities, and a very low thermal IR background. These make it ideal for studies of extra-solar planets and circumstellar discs, as well as for general IR astronomy. In its wide-field mode the NPT provides a 2 degree diameter field for surveys of Kuiper Belt Objects and Near-Earth Objects, surveys central to current intellectual interests in solar system astronomy.