Homogeneous Photometry IV: On the Standard Sequence in the Globular Cluster NGC2419

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Abstract
A new analysis of CCD-based BVRI broad-band photometry for the globular cluster NGC2419 is presented, based on 340 CCD images either donated by colleagues or retrieved from public archives. The calibrated results have been made available through my Web site. I compare the results of my analysis with those of an independent analysis of a subset of these data by Saha et al. (2005, PASP, 117, 37), who have found a color-dependent discrepancy of up to 0.05 mag between their I-band photometry and mine for stars in this cluster. I conclude that a major part of the discrepancy appears to be associated with small (a few hundredths of a second) shutter-timing errors in the MiniMos camera on the WIYN 3.5-m telescope. Smaller contributions to the anomaly likely come from (a) a color-scale error with a maximum amplitude of ~ +/-0.02 mag in my secondary standard list as of September 2004; and (b) statistical effects arising from the previous study's use of a relatively small number of standard-star observations to determine a comparatively large number of fitting parameters in the photometric transformations.

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