Eugene H. Levy's research while affiliated with The University of Arizona and other places
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Publications (25)
The Multichannel Astrometric Photometer (MAP) now in use in the Allegheny Observatory astrometric program is the detector chosen for the strawman design of the Astrometric Telescope Facility (ATF) proposed for the U.S. Space Station. Extrapolation of ground based performance to above atmosphere observing conditions indicates an approximate precisio...
The Astrometric Imaging Telescope (AIT) is a 1.5 to 2 meter diameter space-based telescope designed to carry out a comprehensive program of direct and indirect extra-solar planet detection. The telescope consists of two separate instruments, an astrometric experiment to measure the reflex motion of the parent stars and an imaging coronagraph to dir...
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The Astrometric Imaging Telescope will detect extra-solar planetary systems with imaging and astrometry. The optical system contains a high-efficiency coronagraph and scatter-compensated mirrors to detect Jupiter-size planets around nearby stars. The optical system also is distortion free, tolerant to misalignments, and tolerant to optical surface...
The Astrometric Imaging Telescope (AIT) is designed to probe the circumstellar environment by both direct imaging and indirect astrometric measurements. The Circumstellar Imager (CI) is a coronagraphic camera and is the direct imaging component of the AIT. The CI is designed to obtain high-sensitivity images of the circumstellar region. It provides...
The Astrometric Imaging Telescope (AIT) is a proposed spaceborne observatory whose primary goal is the detecton and study of extra-solar planetary systems. It contains two instruments that use complementary techniques to address the goal. The first instrument, the Coronagraphic Imager, takes direct images of nearby stars and Jupiter-size planets. I...
The present volume on protostars and planets discusses clouds, star
formation, disks and outflows, disk processes and planetary matter, and
planetesimals and planets. Attention is given to nucleosynthesis and
star formation, giant molecular clouds, magnetic fields in star-forming
regions, and the initial stellar population. Topics addressed include...
A moving Ronchi ruling at the focal plane of a telescope has been employed to measure the relative motions of stars with great accuracy. The method has long-term stability and exceptional linearity over a relatively large field-of-view. This measurement technique may prove useful in other applications where such capabilities are required. This pape...
A range of problems aimed primarily at elucidating the character and
consequences of magnetic-field generation in the solar system and at
testing ideas against known properties of natural magnetic fields are
covered. Among the specific subjects currently under investigation are
the magnetohydrodynamic (MHD) character of the protosolar nebula,
inclu...
Measurements of the dc electrical potential near the top of earth's mantle have been extrapolated into the deep mantle in order to estimate the strength of the toroidal magnetic field component at the core-mantle interface. Recent measurements have been interpreted as indicating that at the core-mantle interface, the magnetic toroidal and poloidal...
The system of an astrometric telescope on the Space Station and its support by the Station are described and its feasibility demonstrated. The conceptual design shows that such a facility provides a basis for the study of design alternatives and a point of departure for a detailed design. Basic requirements for this preliminary design are outlined.
The Astrometric Telescope Facility (ATF) proposed for use on NASA's planned Space Station is similar in form and data output to ground-based long focus astrometric instruments. With a focal plane scale of 12.7 arc seconds/mm, the strawman design has a field size of 10 arc min square and a limiting visual magnitude fainter than 16. Output from an ob...
The Astrometric Imaging Telescope (AIT) is a space-based 1.5 to 2 meter diameter telescope designed to discover and study planetary systems around other stars. The measurement objectives and instrument design aim at a definitive search for other planetary systems. The science program includes two planetary-system investigations, and the telescope c...
This paper discusses several planetary science initiatives, planned in
the NASA program, to illustrate the range of the science, the
intellectual depth of the investigations, and human excitement that will
continue to attend solar system exploration in the future. The
anticipated projects that are explicitly described include the
CRAF/Cassini missi...
Many primitive meteorites are composed largely of chondrules, small once-molten beads of glassy rock. The existence of chondrules poses a basic problem for our understanding of the photoplanetary nebula inasmuch as the chondrules seem to have been melted by very short-lived, transient heating events in otherwise cool nebular sorroundings. In this p...
It is shown how it is possible for the Astrometric Telescope Facility (ATF) to utilize the Space Station Freedom as an attached payload by complying with changes in the Station concept and schedule. The ability of the station to accommodate ATF's firm requirements is also addressed. The main factors that led the ATF to utilize the Space Station Fre...
This paper presents a detailed analysis of a space-based telescope requiring an accuracy of 50 pico radians. A relationship between the geometric centroid of a diffraction image and wave aberrations is derived by a combination approach of diffraction optics and geometric optics. Based on sensitivity of the centroid, one-mirror and two-mirror aplana...
Much attention has been given over recent years to the question of discovering planetary systems around other stars. The interest in this question is provoked by both scientific and human imperatives. In this paper, I want to discuss the real intellectual issues that must be confronted in any attempt to discover planetary systems and the implicatio...
The Multichannel Astrometric Photometer now in use in the Allegheny
Observatory astrometric program is the detector chosen for the strawman
design of the Astrometric Telescope Facility proposed for the U.S. Space
Station. Extrapolation of ground based performance to above atmosphere
observing conditions indicates an approximate precision of 0,00001...
It has been proposed that extrasolar planetary systems may be observed if perturbations in star position due to the orbit of Jupiter-type planets could be detected. To see this motion, high accuracy measurements of 0.01 milliarcsecond are required over a relatively large field of view. Techniques using a moving Ronchi grating have been proposed for...
The Astrometric Telescope Facility (ATF) will be operated in the NASA Space Station in the 1990s, furnishing long term, highly accurate relative astrometry of nearby stars in order to detect gravitational perturbations by companion stars with masses as small as that of Neptune. An accuracy of 10 microarcsec is required; this is 100 times better tha...
Citations
... Radial velocity measurements with a precision of ∼1 km s −1 can therefore be used to identify cases in which the companion is stellar. Latham (2003), Charbonneau et al. (2004, and O'Donovan et al. (2006Donovan et al. ( , 2007) describe astrophysical false positives encountered as part of the Vulcan and TrES surveys, detailing how the non-planetary natures of candidate objects were revealed using one or more of the follow-up techniques listed above. An example of a more challenging false positive, and the resource-intensive processes that were employed to reject it, has been detailed by Mandushev et al. (2005). ...
... The nature of the size distribution function (including cutoffs) will impact the values of non-ideal coefficients [208]. Reconnection has been proposed as a mechanism for heating chondrules in the proto-solar nebula [209][210][211][212]. The effects of dust on reconnection have been investigated in cometary magnetotails [213]. ...
... We find that diffraction centroids follow closely the ray centroids at the 30 pas level (after removal of a small linear magnification term). In theory, an image calculated by Fourier Transform of the exit pupil should have exactly the same centroid as the ray distribution (Lawrence et al. 1991 ). We believe that computational approximations account for this difference, which in any case is accommodated in the end-to-end model; the quadratic plate ruling harmonics. ...
... the Copernican principle is the notion that the earth is ordinary in every way that we have been able to test. H. Levy et al.. 1988]. ...
... To realize nlicroarcsecond precision, it will be necessary to launch an orbiting 1.5 m class telescope. A mission to do that called the Astrornetric Imaging Telescope (All') has been proposed, and is described elsewhere in these proceedings (Pravdo et al, 1993). ...
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... The toroidal component of the geomagnetic field is presumed to be located somewhere deep inside the Earth, being inaccessible for contemporary observations, because the Earth's mantle prevents its propagation to the surface. In regards to initial ideas on the Earth's toroidal magnetic field observations, see [23]. ...
