Fast Flat Fields from Scanning Extended Sources

ABSTRACT A fast flat‐fielding algorithm is presented that uses two orthogonal constant‐speed scans of an image across a detector to compute a flat field. Each scan image calibrates the cross‐scan direction of the other. Results from the ISOON solar telescope are presented. For a camera with \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $2048\times 2048$ \end{document} pixels, the computation requires 30 s of processing time and yields a result that is comparable to a Kuhn‐Lin flat field, which requires 1 hr of processing time o...