Advanced Exposure-Time Calculations: Undersampling, Dithering, Cosmic Rays, Astrometry, and Ellipticities
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?
- Publication:
-
Publications of the Astronomical Society of the Pacific
- Pub Date:
- January 2002
- DOI:
- 10.1086/337997
- Bibcode:
- 2002PASP..114...98B
- Keywords:
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- Methods: Data Analysis;
- space vehicles: instruments