2005/07/25 by Brian J. Barris, John L. Tonry, Megan C. Novicki +1 · 5 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Gamma-ray bursts and supernovae #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/491583
published as Astron.J.130:2272-2277,2005 · Accepted to AJ. To be published in November 2005 issue. 16 page, 2 figures, 2 tables. Source code available at http://www.ctio.noao.edu/essence/nn2/
arxiv created 2005/07/25 · openalex publication_date 2005/10/26 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We present a new method for optimally extracting point-source time variability information from a series of images. Differential photometry is generally best accomplished by subtracting two images separated in time, since this removes all constant objects in the field. By removing background sources such as the host galaxies of supernovae, such subtractions make possible the measurement of the proper flux of point-source objects superposed on extended sources. In traditional difference photometry, a single image is designated as the "template" image and is subtracted from all other observations. This procedure does not take all the available information into account and for suboptimal template images may produce poor results. Given N total observations of an object, we show how to obtain an estimate of the vector of fluxes from the individual images using the antisymmetric matrix of flux differences formed from the N ( N - 1)/2 distinct possible subtractions and provide a prescription for estimating the associated uncertainties. We then demonstrate how this method improves results over the standard procedure of designating one image as a template and differencing against only that image.