<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> <!--Converted with LaTeX2HTML 98.1p1 release (March 2nd, 1998) originally by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds * revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan * with significant contributions from: Jens Lippmann, Marek Rouchal, Martin Wilck and others --> <HTML> <HEAD> <TITLE>Convolution and Deconvolution</TITLE> <META NAME="description" CONTENT="Convolution and Deconvolution"> <META NAME="keywords" CONTENT="vol2"> <META NAME="resource-type" CONTENT="document"> <META NAME="distribution" CONTENT="global"> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"> <LINK REL="STYLESHEET" HREF="vol2.css"> <LINK REL="next" HREF="node140.html"> <LINK REL="previous" HREF="node138.html"> <LINK REL="up" HREF="node136.html"> <LINK REL="next" HREF="node140.html"> </HEAD> <BODY > <!--Navigation Panel--> <A NAME="tex2html3172" HREF="node140.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="icons.gif/next_motif.gif"></A> <A NAME="tex2html3169" HREF="node136.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="icons.gif/up_motif.gif"></A> <A NAME="tex2html3163" HREF="node138.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="icons.gif/previous_motif.gif"></A> <A NAME="tex2html3171" HREF="node1.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="icons.gif/contents_motif.gif"></A> <BR> <B> Next:</B> <A NAME="tex2html3173" HREF="node140.html">Other Useful Commands</A> <B> Up:</B> <A NAME="tex2html3170" HREF="node136.html">Spectral Analysis</A> <B> Previous:</B> <A NAME="tex2html3164" HREF="node138.html">Normalization and Fitting</A> <BR> <BR> <!--End of Navigation Panel--> <H2><A NAME="SECTION001063000000000000000"> Convolution and Deconvolution</A> </H2> Estimating the instrumental point spread function and correcting the observed spectra for the instrumental profile by deconvolution<A NAME="5908"> </A> is a delicate subject. Here, the available tools are only briefly mentioned. The point spread function (PSF) can be estimated from the observations (<I>e.g.</I>, from the profile of suitable lines in the comparison, night sky, or interstellar medium spectrum), possibly using the fitting package if a noise-free, analytical approximation is desired. Once this is done, the command <TT>DECONVOLVE/IMAGE</TT> can be applied to deconvolve the observed data. Conversely, the convolution<A NAME="5911"> </A> of, <I>e.g.</I>, a synthetic spectrum with the PSF can be done with the command <TT>CONVOLVE</TT>. <P> <BR><HR> <ADDRESS> <I>Petra Nass</I> <BR><I>1999-06-15</I> </ADDRESS> </BODY> </HTML>
