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Optical and Near-In&ared Photometry of Old Galactic Clusters by Joanne Mcirie Rosvick B.Sc., University of Alberta, 1987 M.Sc., University of Victoria, 1990 A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY in the Department of Physics and Astronomy We accept this dissertation as conforming to the required standaird Dr. C. D. , Supervisor r. T. J. Davidge, Supervisor Dr. F. D. A. Héirtwick, Dr. D. A. VandMBerg, Departmental Member Departmental Member Dr. A. C. Gower, Departmental Member Dr. P. Wan, Outside Member Dr. E. D. Friel, External Examiner ©Joaime Marie Rosvick, 1996 University of Victoria All rights reserved. This dissertation may not be reproduced in whole or in part, by photocopying or other means, without the permission of the author. u Abstract Supervisors: Dr. C. D. Scarfe, Dr. T. J. Davidge The open clusters NGC 2141, NGC 6791, NGC 6819 and NGC 7142, all suspected of having ages greater than 2 billion years (Gyr), were ob served at optical and near-in&ared wavelengths. The images were reduced using standard IRAF routines, and magnitudes for the stars were determined using DAOPHOT (Stetson, 1987). These data were used to construct colour- magnitude diagrams (CMDs) for each cluster, as well as two-colour diagreims {J - K , V - K), {J -H ,H -K ) of the giants. Colour excesses were redetermined by comparing the optical CMD main sequences to semi-empirical ZAMS calibrations (VeindenBerg and PoU, 1989; this work) and are as follows: E{B — V) = 0.32 ± 0.04, 0.23 ± 0.03, 0.11 ± 0.03 and 0.29 ± 0.04, for NGC 2141, NGC 6791, NGC 6819 and NGC 7142, respectively.
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