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J. Melbourne, A. Sarajedini (Wesleyan University), A. Layden (Bowling Green State University), D. H. Martins (University of Alaska)
We present the first CCD photometry for the Galactic globular cluster NGC 4833. Our BVI color magnitude diagrams (CMD) extend from above the red giant branch (RGB) tip to several magnitudes below the main sequence turn off. The cluster horizontal branch (HB) is predominately blueward of the instability strip with 13 confirmed RR Lyrae variables and 5 additional RR Lyrae candidates. The principal sequences of the cluster are well-defined but show the effects of differential reddening. To correct for this, we have created a local extinction map, which is consistent with IRAS and COBE/DIRBE maps of the region. Using the corrected photometry, we determine the mean V magnitude of the HB from the confirmed RR Lyrae variables, the metallicity of the cluster, and the absolute reddening in the direction of NGC 4833. Finally, from the main sequence turnoff, we estimate an age for the cluster.
The author(s) of this abstract have provided an email address for comments about the abstract: jmel@astro.wesleyan.edu