Linking multi-epoch CCD photometry of partially overlapping fields
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Date
2013
Authors
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Journal ISSN
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Publisher
Oxford University Press
Abstract
A common problem in CCD photometry is to combine measurements obtained at different
epochs. This is especially challenging if the fields only overlap partially, and are sparse, so
that not all calibrating stars are observed at all epochs. A least-squares method for determining
zero-points for all epochs under these circumstances is formulated. Allowance is made not
only for the presence of intra-night measurement errors, but also for epoch-to-epoch scatter in
star brightnesses (due, for example, to slow variability or instrumental effects). Expressions are
derived for the uncertainties in the estimated zero-points. Three different criteria for selecting
optimal calibrating subsets of the available group of stars are introduced. Simulations show
that if intra-night variability dominates, it may be best to use all available stars for zero-point
determinations. On the other hand, if epoch-to-epoch scatter dominates, smaller subsets of
stars may give superior results. Characterization of the uncertainty in the estimated variance
of epoch-to-epoch variability remains an important outstanding problem.
Description
Keywords
Methods: observational, Methods: statistical, Techniques: photometric
Citation
Koen, C. (2013). Linking multi-epoch CCD photometry of partially overlapping fields. 431(2): 1048–1061