| An Atlas of [N ii] and [O iii] Images and Spectra of Planetary Nebulae |
APR 2007 |
40 pages |
| Authors:
Arsen R. Hajian; Steven M. Movit; Denis Trofimov; Bruce Balick; Yervant Terzian; Kevin H. Knuth; Domhnull Granquist-Fraser; Karen A. Huyser; Andre Jalobeanu; Dawn McIntosh; NAVAL OBSERVATORY WASHINGTON DC ASTRONOMICAL APPLICATIONS DEPT
|
 | We present an atlas of Hubble Space Telescope images and ground-based, long-slit, narrowband spectra centered on the 6584 Angstrom line of [N ii] and the 5007 Angstrom line of [O iii]. The spectra were obtained for a variety of slit positions across each target (as shown on the images) in an effort to account for nonspherical nebular geometries in a robust manner. We have extended the prolate ellipsoidal shell model ... |
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| Gauge Symmetry of the N-body Problem in the Hamilton-Jacobi Approach |
12 JAN 2004 |
25 pages |
| Authors:
Michael Efroimsky; Peter Goldreich; NAVAL OBSERVATORY WASHINGTON DC ASTRONOMICAL APPLICATIONS DEPT
|
| In most books the Delannay and Lagrange equations for the orbital elements are derived by the Hamilton-Jacobi method: one begins with the two-body Hamilton equations in spherical coordinates, performs a canonical transformation to the orbital elements, and obtains the Delannay system. A standard trick is then used to generalise the approach to the N-body case. We re-examine this step and demonstrate that it contains an implicit condition which restricts the ... |
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| Another Look at Non-Rotating Origins |
22 JUL 2003 |
5 pages |
| Authors:
George H. Kaplan; NAVAL OBSERVATORY WASHINGTON DC ASTRONOMICAL APPLICATIONS DEPT
|
| Two "non-rotating origins" were defined by the IAU in 2000 for the measurement of Earth rotation: the Celestial Ephemeris Origin (CEO) in the ICRS and the Terrestrial Ephemeris Origin (TEO) in the ITRS. Universal Time (UT1) is now defined by an expression based on the angle theta between the CEO and TEO. Many previous papers, e.g., Capitaine, Guinot, & McCarthy (2000), developed the position of the CEO in terms of ... |
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| Gauge Freedom in the N-body Problem of Celestial Mechanics |
07 JUL 2003 |
23 pages |
| Authors:
Michael Efroimsky; Peter Goldreich; NAVAL OBSERVATORY WASHINGTON DC ASTRONOMICAL APPLICATIONS DEPT
|
| Whenever a standard system of six planetary equations(in the Lagrange, Delaunay, or other form) is employed, the trajectory resides on a 9(N- 1)-dimensional submanifold of the 12(N-1)-dimensional space spanned by the orbital elements and their time derivatives. The freedom in choosing this submanifold reveals an internal symmetry inherent in the description of the trajectory by orbital elements. This freedom is analogous to the gauge invariance of electrodynamics. In traditional derivations ... |
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| US Naval Observatory Ephemerides of the Largest Asteroids |
FEB 1999 |
11 pages |
| Authors:
James L. Hilton; NAVAL OBSERVATORY WASHINGTON DC ASTRONOMICAL APPLICATIONS DEPT
|
| A new set of ephemerides for 15 of the largest asteroids has been produced for use in the Astronomical Almanac. The ephemerides cover the period from 1800 through 2100. The internal uncertainty in the mean longitude at epoch, 1997 December 18, ranges from 0",05 for 7 Iris through 0",22 for 65 Cybele, and the uncertainty in the mean motion varies from 0",02 per century for 4 Vesta to 0",14 per ... |
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| A Comparison of Radio and Optical Astrometric Reduction Algorithms |
1998 |
16 pages |
| Authors:
G. H. Kaplan; NAVAL OBSERVATORY WASHINGTON DC ASTRONOMICAL APPLICATIONS DEPT
|
| This paper examines the correspondence between two approaches to astrometric observational reductions: the approach based on angular observables used for optical observations, and the approach based on the interferometric delay observable used for very long baseline radio interferometry (VLBI) observations. Specifically, of interest here is the group of algorithms that have become standard in accounting for the physical effects traditionally called annual and diurnal aberration and gravitational light bending. These ... |
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| A Navigation Solution Involving Changes to Course and Speed |
SEP 1996 |
22 pages |
| Authors:
George H. Kaplan; NAVAL OBSERVATORY WASHINGTON DC ASTRONOMICAL APPLICATIONS DEPT
|
| In a previous paper, an approach to celestial navigation was presented that allows a vessel's latitude, longitude, course, and speed to be simultaneously estimated. The development assumed that the vessel was sailing a rhumb-line track at a constant speed. In this paper, the approach is extended to cover the case where observations are taken over several legs of a voyage. A single least-squares solution for all sailing parameters is developed. ... |
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| Analytical Study of Optical Wavefront Aberrations Using Maple |
01 MAY 1996 |
29 pages |
| Authors:
Marc A. Murison; NAVAL OBSERVATORY WASHINGTON DC ASTRONOMICAL APPLICATIONS DEPT
|
| This paper describes a package for analytical ray tracing of relatively simple optical systems. AESOP (An Extensible Symbolic Optics Package) enables analysis of the effects of small optical element misalignments or other perturbations. (It is possible to include two or more simultaneous independent perturbations.) Wavefront aberrations and optical path variations can be studied as functions of the perturbation parameters. The power of this approach lies in the fact that the ... |
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| The Motion of the Observer in Celestial Navigation |
1996 |
8 pages |
| Authors:
George H. Kaplan; NAVAL OBSERVATORY WASHINGTON DC ASTRONOMICAL APPLICATIONS DEPT
|
| The object of celestial navigation is the determination of the latitude and longitude of a vessel at a specific time, through the use of observations of the altitudes of celestial bodies. Each observation defines a circle of position on the surface of the Earth, and the small segment of the circle that passes near the observer's estimated position is represented as a line of position (LOP). A position fix is ... |
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| The Motion of Mars Pole I. Rigid Body Precession and Nutation. |
OCT 1991 |
19 pages |
| Authors:
James L. Hilton; NAVAL OBSERVATORY WASHINGTON DC ASTRONOMICAL APPLICATIONS DEPT
|
| Differences between the observed forced nutation component amplitudes of the Earth and predicted nutation amplitudes for a rigid Earth are a result of differences between the theoretical rigid structure of the Earth used in older models and the actual elastic Earth with a liquid core. However, except for the period of the Chandler wobble, the observations of the motion of the Earth's pole were not accurate enough to observe the ... |
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| Analysis of Ancient Chinese Records of Occultations between Planets and Stars |
OCT 1988 |
14 pages |
| Authors:
James L. Hilton; P. K. Seidelmann; Liu Ciyuan; NAVAL OBSERVATORY WASHINGTON DC ASTRONOMICAL APPLICATIONS DEPT
|
| One hundred seventy-three historical Chinese records of occultations and appulses (conjunctions with small least separations) of planets with stars, other planets, and extended objects were examined. The observations were made by the Chinese imperial astronomers from 12 December 146 B.C. to 3 February 1761 A. D. and preserved in the Chinese dynastic histories. Sixty-six of the records were of occultations, 83 records were of appulses, and 24 records were questionable ... |
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