منابع مشابه
Comparing Tycho–2 Astrometry with Ucac1
The Tycho–2 Catalogue, released in February 2000, is based on the ESA Hipparcos space mission data and various ground–based catalogs for proper motions. An external comparison of the Tycho–2 astrometry is presented here using the first U.S. Naval Observatory CCD As-trograph Catalog (UCAC1). The UCAC1 data were obtained from observations performed at CTIO between February 1998 and November 1999,...
متن کاملConfusion errors in astrometry and counterpart association
In very crowded fields, the modulation of the background by the sea of unresolved faint sources induces centroid shifts. The errors increase with the number of sources per beam. Even the most optimistic simulations of imaging data show that position errors can become severe (on the order of the beam size) at flux levels at which images contain 1/100 to 1/20 sources per beam, depending on the sl...
متن کاملOn the convergence of three-step random iterative procesess with errors of nonself asymptotically nonexpansive random mappings
begin{abstract} In this paper, we prove some strong and weak convergence of three step random iterative scheme with errors to common random fixed points of three asymptotically nonexpansive nonself random mappings in a real uniformly convex separable Banach space. end{abstract}
متن کاملConfirmation of Errors in Hipparcos Parallaxes from Hst/fgs Astrometry of the Pleiades
We present absolute trigonometric parallaxes and relative proper motions for three members of the Pleiades star cluster, obtained with HST’s Fine Guidance Sensor 1r, a white-light interferometer. We estimate spectral types and luminosity classes of the stars comprising the astrometric reference frame from R ≈ 2, 000 spectra, VJHK photometry, and reduced proper motions. From these we derive esti...
متن کاملRandom errors in egocentric networks
The systematic errors that are induced by a combination of human memory limitations and common survey design and implementation have long been studied in the context of egocentric networks. Despite this, little if any work exists in the area of random error analysis on these same networks; this paper offers a perspective on the effects of random errors on egonet analysis, as well as the effects...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1995
ISSN: 0074-1809
DOI: 10.1017/s007418090022857x