CCD Photometry of the Globular Cluster NGC 1261

1 December 1989

journal article
research article
Published by IOP Publishing in Publications of the Astronomical Society of the Pacific

Vol. 101 (646) , 1088
https://doi.org/10.1086/132582

Abstract

CCD photometry of the halo globular cluster NGC 1261 is presented. This is the first CCD study of the cluster and the first published photometry of main-sequence stars in the cluster. The distance modulus, based on the apparent magnitude of the horizontal branch and the fitting of the main sequence to two subdwarfs, is determined to be (m M) 16.05±0.25. The positions of the NGC 1261 unevolved main sequence, main-sequence turnoff, and subgiant branch are matched well by 15 Gyr isochrones interpolated from the grid of VandenBerg and Bell (1985) for [M/H] 1.09, Y 0.25, and assuming a reddening value toward the cluster of E(B V) 0.02, or by [M/H] -1.27, Y 0.25, 15 Gyr isochrones with E(B -V) 0.04. The color-magnitude diagram (CMD) we measure for NGC 1261 matches in detail that of the "standard" cluster MS indicating that these two clusters have similar values of metallicity and age.

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