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Description
The h and chi Per "double cluster" is examined using wide-field (0.98x0.98{deg}) CCD UBV imaging supplemented by optical spectra of several hundred of the brightest stars. The UBV photometry was obtained from observations with the 0.9m telescope at Kitt Peak National Observatory using the Mosaic CCD camera (0.43arcsec/pix) on 1999 February 3. Conditions were photometric with a seeing about 1.3arcsec. The Mosaic camera consists of eight individual SITe 2048x4096 CCD chips arranged in two rows of four to produce a final image equivalent to 8192x8192 pixels (098x098{deg}) but with modest (35-50pix) gaps. Our imaging data set contains short (0.5s in V and B and 2s in U), medium (2s in V and B and 10s in U), and long (100s in V and B and 300s in U) integrations, each consisting of five dithered exposures that were combined to fill in gaps between the eight chips. Analyzing the data near the cluster nuclei results in identical reddenings E(B-V) (0.56+/-0.01), distance moduli (11.85+/-0.05), and ages (12.8+/-1.0Myr) for the two clusters. In addition, the initial mass function slope for each of the cluster nuclei is found to be quite normal for high-mass stars ({Gamma}=-1.3+/-0.2), indistinguishable from a Salpeter value. The masses of the two clusters are found to be 3700M_{sun}_ and 2800M_{sun}_ for h and {chi} when integrating the present-day mass function from 1 to 120M_{sun}_.
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