| Popis: |
We present UBVI CCD photometry in the region of the open clusters Koposov 12, Koposov 53 and Koposov 77. The optical CCD data for these clusters are obtained for the first time. The radii are found to be 4.6, 4.2 and 2.4 arcmin. The reddenings E(B−V) are 0.51 ± 0.05, 0.41 ± 0.05 and 0.56 ± 0.05 mag for Koposov 12, Koposov 53 and Koposov 77, respectively, while the corresponding distances are 2.0 ± 0.2, 5.3 ± 0.5 and 5.4 ± 0.5 kpc. Comparison with Z= 0.008 isochrones leads to an age of 0.6 ± 0.2 Gyr for Koposov 12. Ages of 89 ± 10 Myr for Koposov 53 and 1.2 ± 0.3 Gyr for Koposov 77 are determined using the isochrones of Z= 0.019. Our analysis shows that the reddening law is normal towards the clusters under study. |
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