Download or read book Description of the U S Naval Observatory Astrometric Interferometer written by and published by . This book was released on 1990 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book United States Naval Observatory written by United States Naval Observatory and published by . This book was released on 1993 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book United States Naval Observatory Astrometric Interferometer written by Donald John Hutter and published by . This book was released on 1994 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 are located in a Y-shaped configuration, and features a full-array laser metrology system to monitor baseline motion. The AI shares with the BOA state-of-the-art delay lines and a real-time zero- order fringe tracking system. The AI will have a limiting magnitude of 10 and will produce star positions accurate to a few milliarcseconds (mas). With a planned operational lifetime of several decades, this instrument will be capable of maintaining the HIPPARCOS reference frame through repeated observations, yielding improved proper motions of thousands of the brighter HIPPARCOS stars.
Download or read book U S Naval Observatory Optical Interferometer Project AZ CA written by and published by . This book was released on 1992 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Publications of the United States Naval Observatory written by United States Naval Observatory and published by . This book was released on 1900 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Publications of the United States Naval Observatory written by United States Naval Observatory and published by . This book was released on 1905 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Navy Prototype Optical Interferometer written by John Thomas Armstrong and published by . This book was released on 1998 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: We describe the Navy Prototype Optical Interferometer (NPOI), a joint project of the Naval Research Laboratory (NRL) and the US Naval Observatory (USNO) in cooperation with Lowell Observatory. The NPOI has recently begun operations at the Lowell Observatory site near Flagstaff, Arizona, obtaining its first images, of a binary star, in 1996 May and June and its first limb-darkening observations during 1996 November to 1997 February. This paper gives an overview of the NPOI, including the characteristics of optical interferometry that affect its design. The NPOI includes subarrays for imaging and for astrometry. The imaging subarray consists of six moveable 50 cm siderostats feeding 12 cm apertures, with baseline lengths from 2.0 to 437 m. The astrometric subarray consists of four fixed 50 cm siderostats feeding 12 cm apertures (35 cm apertures to be installed in 1998), with baseline lengths from 19 m to 38 m. The shared back end covers 450-850 nm in 32 channels. The NPOI features vacuum feed and delay systems, active group-delay fringe tracking, and a high degree of automation. The astrometric subarray also includes an extensive site laser metrology system to measure the motions of the siderostats with respect to one another and to the bedrock. For imaging stellar surfaces, arrays with equal spacing between elements are superior to arrays that have been laid out to optimize (u, v) coverage and that therefore have unequal spacing. The imaging subarray of the NPOI provides a number of equally spaced configurations with linear scales at ratios of 1.64. Unequally spaced configurations are available for a variety of other imaging programs. Coherence across either type of imaging configuration is maintained by phase bootstrapping: the phases on the longest baselines, on which fringes may be too weak to track, are stabilized by tracking fringes on the shortest baselines.
Download or read book United States Naval Observatory written by United States Naval Observatory and published by . This book was released on 1976 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Publications of the United States Naval Observatory written by United States Naval Observatory and published by . This book was released on 1975 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Astronomical Magnetic and Meteorological Observations Made at the United States Naval Observatory written by United States Naval Observatory and published by . This book was released on 1853 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reprint written by United States Naval Observatory and published by . This book was released on 1970 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Very High Angular Resolution Imaging written by J.G. Robertson and published by Springer Science & Business Media. This book was released on 2013-12-01 with total page 505 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 together workers from all wavelength ranges to discuss the details of the science and art of "Very High Angular Resolution Imaging" . While the main emphasis of Symposium No. 158 was on high resolution tech niques from the radio, mm-wave, infrared and optical bands, it also provided an opportunity for presentation of astronomical results from these techniques. As well as giving our colleagues from the Northern Hemisphere a break from midwinter, the location of the Symposium in Australia recognised the continuing development of astronomical interferometry in this country, especially the recent completion of the Australia Telescope radio array, and the progress toward com missioning of the Sydney University Stellar Interferometer. A number of the par ticipants visited these instruments during the post-symposium tour.
Download or read book Publications written by United States Naval Observatory and published by . This book was released on 1926 with total page 1124 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Astronomical and Astrophysical Objectives of Sub Milliarcsecond Optical Astrometry written by Erik Høg and published by Springer Science & Business Media. This book was released on 2013-12-01 with total page 427 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astrometry is on the threshold of great changes due to the fact that this decade, alone, is witnessing an improvement of stellar positions equivalent to the total improvement of the previous two centuries. The Hipparcos Satellite has concluded its observations, and the catalog is in preparation. Preliminary results assure that the Hipparcos catalog will provide positions, parallaxes and annual proper motions for over 100,000 stars with accuracies of 1.5 milliarcseconds. In addition, the Tycho catalog will provide positions of about 30 milliarcseconds accuracy for over 1 million stars, and annual proper motions with 3 milliarcsecond accuracy will subsequently be ob tained by means of first epoch positions from the Astrographic Catalog. Optical interferometers on the ground are beginning operation, and these instruments can provide observational accuracies of approximately one milliarcsecond. Also, the traditional reference frame based on the Fun damental Catalog of bright stars is being replaced by the extragalactic ref erence frame, based on radio sources with accuracies of one milliarcsecond. Thus, astrometry will change from a fundamental reference frame defined in terms of the dynamical reference frame of the solar system with accuracies of 100 milliarcseconds to a space-fixed, extragalactic reference frame with accuracies of one milliarcsecond. Future astrometric observations should be in the 1 -100 milliarcsecond accuracy range. There are a number of concepts for future astrometric instruments in space. Most of these can provide sub-milliarcsecond astrometric accuracies.
Download or read book Instruments and Publications of the United States Naval Observatory written by United States Naval Observatory and published by . This book was released on 1876 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book United States Naval Observatory Circular written by United States Naval Observatory and published by . This book was released on 1964 with total page 798 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Encyclopedia of Astronomy Astrophysics written by P Murdin and published by CRC Press. This book was released on 2001-01-01 with total page 5610 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a unique collaboration, Nature Publishing Group and Institute of Physics Publishing have published the most extensive and comprehensive reference work in astronomy and astrophysics. This unique resource covers the entire field of astronomy and astrophysics and this online version includes the full text of over 2,750 articles, plus sophisticated search and retrieval functionality and links to the primary literature. The Encyclopaedia's authority is assured by editorial and advisory boards drawn from the world's foremost astronomers and astrophysicists. This first class resource is an essential source of information for undergraduates, graduate students, researchers and seasoned professionals, as well as for committed amateurs, librarians and lay people wishing to consult the definitive astronomy and astrophysics reference work.
