DETECTION AND MEASUREMENT OF POORLY SAMPLED POINT SOURCES IMAGED WITH2-D ARRAYS

Imaging systems in which the pixels are large compared to the point sp read function produce undersampled data for which traditional 2-D Gaus sian PSF fitting will not work well. Such systems include wide-field i maging applications (CCD mosaics) and space-based telescopes. The curr ent astronomical literature provides few recipes to use when dealing w ith undersampled data. We present a method of providing optimum signal -to-noise data matching for poorly sampled point sources which makes u se of profile fitting but only within small, variable-size pixel masks . A wide-field imaging Schmidt telescope project, Lowell Observatory N ear-Earth Object Search (LONEOS), is discussed as an example. Our pixe l mask technique is applied to model images from the LONEOS camera, an d we show that we can determine point-source centroids and brightnesse s with good precision, even for faint objects. (C) 1996 American Astro nomical Society.