CCD astrometry and photometry of IAU reference frame benchmark radio sources
نویسندگان
چکیده
منابع مشابه
Optical astrometry of Benchmark radio sources - IV. New results in the southern hemisphere
Optical positions relative to the International Reference Stars Catalogue (IRS), and therefore in the system of the FK5, have been obtained for the optical counterparts of 40 compact extragalactic radio sources south of δ ∼ +6◦. Many of these sources are being considered as possible Benchmark objects for the establishment of a quasi−inertial unified radio/optical reference frame. Precision leve...
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was found in an earlier investigation on dark matter in open clusters mainly situated in the northern sky. Taking into account the small number of clusters investigated as weil as the large mean errors, the result cannot be regarded as fully conclusive. It nevertheless gives an indication that the dark matter (dust) has been driven away from the cluster and that the remaining dark matter inside...
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While it is apparent that many comets are active beyond the canonical distance of 3 AU, few surveys of cometary activity have been performed in this region previously. Such a survey enables a more accurate determination of the proportion of comets that exhibit little or no outgassing at these distances. Results are presented of CCD observations of comets in the region of 3 AU ≤ Rh ≤ 6 AU obtain...
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Strömgren uvby CCD photometry can be used in a variety of ways to constrain the absolute and relative ages of globular clusters. The reddening corrected v−y, c1 diagram offers the means to derive ages that are completely independent of distance. Very precise differential ages for clusters of the same chemical composition may also be determined from such 2–color plots, or from measurements of th...
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 1984
ISSN: 0035-8711,1365-2966
DOI: 10.1093/mnras/211.3.713