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Sky and Ocean Joined
As one of the oldest scientific institutions in the United States, the US Naval Observatory has a rich and colourful history. This volume is, first and foremost, a story of the relations between space, time and navigation, from the rise of the chronometer in the United States to the Global Positioning System of satellites, for which the Naval Observatory provides the time to a billionth of a second per day. It is a story of the history of technology, in the form of telescopes, lenses, detectors, calculators, clocks and computers over 170 years. It describes how one scientific institution under government and military patronage has contributed, through all the vagaries of history, to almost two centuries of unparalleled progress in astronomy. Sky and Ocean Joined will appeal to historians of science, technology, scientific institutions and American science, as well as astronomers, meteorologists and physicists.
Air Force Register
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The Effects of Atmospheric Calibration Errors on Source Model Parameters
Optical long-baseline interferometric data is commonly calibrated with respect to an external calibrator, which is either an unresolved source or a star with a known angular diameter. A typical observational strategy involves acquiring data in a sequence of calibrator-target pairs, where the observation of each source is obtained separately. Therefore, the atmospheric variations that have time scales shorter than the cadence between the target-calibrator pairs are not always fully removed from the data even after calibration. This results in calibrated observations of a target star that contain unknown quantities of residual atmospheric variations. We describe how Monte Carlo simulations can be used to assess quantitatively the impact of atmospheric variations on fitted model parameters, such as angular diameters of uniform-disk models representing semi- and fully-resolved single stars.
Very High Angular Resolution Imaging
The 1990s are proving to be a very exciting p&iod for high angular resolution astronomy. At radio wavelengths a combination of new array instruments and pow erful imaging algorithms have generated images of unprecedented resolution and quality. In the optical and infrared, the great technical difficulties associated with constructing separated-aperture interferometers have been largely overcome, and many new instruments are now operating or are being developed. As these pro grams start to produce observational results they will be able to draw extensively on the experience gained by the radio-interferometry community. Thus it seemed that the time was ripe for a meeting which would bring toge...
Reference Systems
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United States Naval Observatory Astrometric Interferometer
The U.S. Naval Observatory Astrometric Interferometer (AI) is the dedicated astrometric subarray of the new Navy Prototype Optical Interferometer (NPOI) at Lowell Observatory, which is being built in collaboration with the Naval Research Laboratory. The Naval Research Laboratory is constructing the imaging subarray of the NPOI, the 'Big Optical Array' (BOA). The AI will be in operation on Anderson Mesa, near Flagstaff, Arizona, in the spring of 1994. The AI was built using the experience gained from the Mark III Interferometer on Mt. Wilson, CA, which demonstrated 'proof of concept' of wide-angle astrometry by a long baseline optical interferometer. The AI incorporates four siderostats that ...
Scientific and Technical Aerospace Reports
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Fundamental Stellar Properties: The Interaction Between Observation and Theory
This Symposium began with a proposal for a meeting to honour Emer itus Professor Robert Hanbury Brown on the occasion of his 80th birthday. He requested that any such meeting should be on a topic that would be of benefit to the Sydney University Stellar Interferometer (SUSI) program. With SUSI and several other high angular resolution instruments either in operation or coming on line within the next decade, and with advances in astrometry, spectroscopy and in theoretical models of stellar atmospheres and interiors, it appeared to be both appropriate and timely to hold a symposium on "Fundamental Stellar Properties: the Interaction between Observation and Theory. " The emphasis of the meeting...
