From simulation, precision of the determined lunar physical libration is expected to be several milliarcsecs, about two orders of magnitude better than the current precision of libration by lunar laser ranging observation. The principle and feasibility of the method of in-situ observation are also demonstrated. The concept and design of this telescope are firstly introduced in this paper. Libration is to be measured and studied from celestial motion of the directions of three FOVs from image processing. It passively, continuously and simultaneously observe stars in three FOVs along with rotation of the Moon. The telescope can be placed at any place with any attitude on the Moon and do not require manned install, control or operation. In this paper, we propose a brand new optical telescope functioned with simultaneously observing multiple (here there are three) fields of view (FOVs) for in-situ observation of lunar physical libration. All rights reserved.įor lots of scientific questions about lunar physics deep inside the Moon, in-situ observation on lunar physical libration is one of the most potential ways. Although the Gaia mission is poised to set the new standard in catalog astronomy and will in many ways supersede this catalog, the methods and procedures reported here will prove useful to remove astrometric magnitude- and color-dependent systematic errors from the next generation of ground-based surveys reaching significantly deeper than the Gaia catalog. This makes our compilation one of the deepest and densest ICRF-registered astrometric catalogs outside the galactic plane. As a result, the coordinate axes realized by our astrometric data are believed to be aligned with the extragalactic radio frame to within ☐.2 mas at the reference epoch J2000.0. Alignment with the International Celestial Reference System was made using 1288 objects common to the second realization of the International Celestial Reference Frame (ICRF2) at radio wavelengths. The catalog covers 22,525 square degrees and lists 100,774,153 objects to the limiting magnitude of RF ∼ 20.8. The resulting global zero point error is less than 0.6 mas yr-1, and the precision is better than 4.0 mas yr-1 for objects brighter than RF = 18.5, rising to 9.0 mas yr-1 for objects with magnitudes in the range 18.5 < RF < 20.0. As special attention was devoted to the absolutization process and the removal of position, magnitude, and color dependent systematic errors through the use of both stars and galaxies, this release is solely based on plate data outside the galactic plane, i.e., ?b? ≥ 27°. Future astrometric space missions are necessary to significantly improve our present knowledge of the space motion of the two most conspicous galactic neighbours of the Milky Way.We present a new catalog of absolute proper motions and updated positions derived from the same Space Telescope Science Institute digitized Schmidt survey plates utilized for the construction of Guide Star Catalog II. Recent theoretical work concerning the origin of the Magellanic System is briefly reviewed, but a unique model of the Magellanic Stream, for the origin of the Magellanic Clouds, and for the mass distribution in the Galaxy cannot yet be decided upon. Within the uncertainties, the LMC and SMC are found to be on parallel trajectories. The corresponding galactocentric space motion vectors are computed. Combining the three independent measurments of the proper motion of the LMC and the two independent measurements of the proper motion of the SMC improves the estimate of the proper motion of the LMC and SMC. (1994), which is about 7.3 kpc distant from the center of the LMC, also suggeests clockwise rotation. Comparison of the Hipparcos proper motion with the proper motion of the field used by Jones et al. For the LMC the Hipparcos data suggest a weak rotation signal in a clockwise direction on the sky. (1994) using background galaxies in a far-outlying field of the LMC. The Hipparcos proper motions are in agreement with previous measurements using PPM catalogue data by Kroupa et al. Both galaxies are moving approximately parallel to each other on the sky, with the Magellanic Stream trailing behind. For the SMC, μ αcos( δ) = 1.23☐.84 mas/yr, μ δ = −1.21☐.75 mas/yr is obtained, whereby care is taken to exclude likely tidal motions induced by the LMC. A correctly weighted mean of the data yields the presently available most accurate values, μ αcos( δ) = 1.94☐.29 mas/yr, μ δ = −0.14☐.36 mas/yr for the LMC. Hipparcos measured 36 stars in the LMC and 11 stars in the SMC. The proper motion of the Large (LMC) and Small (SMC) Magellanic Cloud using data acquired with the Hipparcos satellite is presented.
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