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A multicolor survey of absolute proper motions: galactic structure and kinematics in the direction of the galactic center at intermediate latitude.
Bienayme et al. (1992) have published a magnitude-limited sample ofproper motions for stars at the intermediate galactic latitude (l=3deg,b=47deg; α_1950_=15h18m, δ_1950_=+02d16') for a 2 squaredegree field. In their study there was a lack of an accurate absoluteastrometric reference due to very small number of galaxies orextragalactic objects in the field. However, since Bienayme et al.paper, more deep photographic plates and CCD standards have beenobtained. Here we have derived a new photographic photometry and propermotions for ~20000 stars with completeness to V~18 in the same directionfor a 15.5 square degree field. The combination of four glass copies ofthe Palomar Observatory Sky Survey (i.e. POSS 1402 E&O and POSS 1429E&O) has been used as a first epoch for proper motion determination.The random error of the proper motions is approximately 0.3"/century toV~17. The photometric accuracy ranges between 0.07 to 0.10 in the V, Band U bands. We stress the importance of the magnitude and color effectsin astrometric surveys of field stars. Using color-magnitude diagrams ofa few cluster member stars, a new distance of 6.9+/-0.5kpc is derivedfor M5 and 20.3+/-0.8kpc for Pal 5 globular clusters. This is in goodagreement with other determinations. We have analyzed the components ofU+W and V galactic space motions resulting from the accurate propermotions survey. No dependence with z distance is found in the asymmetricdrift of the thick disk population. New estimates of the parameters ofthe velocity ellipsoid have been derived for the thin disk, thick diskand halo populations of the Galaxy.
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Yilan |
| Sað Açýklýk: | 15h12m37.49s |
| Yükselim: | -00°22'53.8" |
| Görünürdeki Parlaklýk: | 7.252 |
| Uzaklýk: | 204.499 parsek |
| özdevim Sað Açýklýk: | 4.2 |
| özdevim Yükselim: | -7.6 |
| B-T magnitude: | 9.435 |
| V-T magnitude: | 7.433 |
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