122 research outputs found
A catalog of 120 NGC open star clusters
A sample of 145 JHK--2MASS observations of NGC open star clusters is studied,
of which 132 have never been studied before. Twelve are classified as non-open
clusters and 13 are re-estimated self-consistently, after applying the same
methods in order to compare and calibrate our reduction procedures. The
fundamental and structural parameters of the 120 new open clusters studied here
are derived using color-magnitude diagrams of JHK Near-IR photometry with the
fitting of solar metallicity isochrones. We provide here, for the first time, a
catalog of the main parameters for these 120 open clusters, namely, diameter,
distance, reddening and age.Comment: 18 pages, 7 figures, Published in Journal of The Korean Astronomical
Society 44: 1-11, 2011 Februar
CCD BVRI and 2MASS Photometry of the Poorly Studied Open Cluster NGC 6631
Here we have obtained the {\it BVRI CCD} photometry down to a limiting
magnitude of 20 for the southern poorly studied open cluster NGC 6631.
It is observed from the {\it 1.88 m} Telescope of Kottamia Observatory in
Egypt. About 3300 stars have been observed in an area of around the cluster center. The main photometric parameters
have been estimated and compared with the results that determined for the
cluster using {\it JHKs 2MASS} photometric database. The cluster's diameter is
estimated to be 10 arcmin; the reddening E(B-V)= 0.68 0.10 mag, E(J-H)=
0.21 0.10 mag, the true modulus (m-M)= 12.16 0.10 mag, which
corresponds to a distance of 2700 125 pc and age of 500 50 Myr.Comment: 13 pages, 6 figure
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