Advanced Exposure‐Time Calculations: Undersampling, Dithering, Cosmic Rays, Astrometry, and Ellipticities
Open Access
- 1 January 2002
- journal article
- research article
- Published by IOP Publishing in Publications of the Astronomical Society of the Pacific
- Vol. 114 (791) , 98-111
- https://doi.org/10.1086/337997
Abstract
The familiar tools of Fourier analysis and Fisher matrices are applied to derive the uncertainties on photometric, astrometric, and weak‐lensing measurements of stars and galaxies in real astronomical images. Many effects or functions that are ignored in basic exposure‐time calculators can be included in this framework: pixels of size comparable to the stellar image, undersampled and dithered exposures, cosmic‐ray hits, intrapixel sensitivity variations, and positional and ellipticity errors, as well as photometric errors. I present a formalism and a C++ implementation of these methods. As examples of their use, I answer some commonly arising questions about imaging strategies: What amount of dithering is ideal? What pixel size optimizes the productivity of a camera? Which is more efficient—space‐based or ground‐based observing?Keywords
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