<!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>Identification loop</TITLE> <META NAME="description" CONTENT="Identification loop"> <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="node163.html"> <LINK REL="previous" HREF="node161.html"> <LINK REL="up" HREF="node158.html"> <LINK REL="next" HREF="node163.html"> </HEAD> <BODY > <!--Navigation Panel--> <A NAME="tex2html3458" HREF="node163.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="icons.gif/next_motif.gif"></A> <A NAME="tex2html3455" HREF="node158.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="icons.gif/up_motif.gif"></A> <A NAME="tex2html3449" HREF="node161.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="icons.gif/previous_motif.gif"></A> <A NAME="tex2html3457" 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="tex2html3459" HREF="node163.html">Resampling and checking the</A> <B> Up:</B> <A NAME="tex2html3456" HREF="node158.html">Wavelength Calibration</A> <B> Previous:</B> <A NAME="tex2html3450" HREF="node161.html">Estimating the angle of</A> <BR> <BR> <!--End of Navigation Panel--> <H2><A NAME="SECTION001164000000000000000"> Identification loop</A> </H2> <P> The identification criterion combines estimate of the wavelength of a line and an estimate of the error as well as a list laboratory wavelengths to determine and guarantee the identification of a given line. One could involve the additional knowledge of line strengths. But in practice this information of limited use, in reason of variations of relative line intensities caused by impurities, lamp ageing, pressure variations, a.s.o. Accordingly, the identification criterion is: <P> <DIV ALIGN="CENTER"> <!-- MATH: $\lambda_c \equiv \lambda_{cat}$ --> <IMG WIDTH="46" HEIGHT="41" ALIGN="MIDDLE" BORDER="0" SRC="img312.gif" ALT="$ \lambda_c \equiv \lambda_{cat}$"> if <IMG WIDTH="42" HEIGHT="56" ALIGN="BOTTOM" BORDER="0" SRC="img313.gif" ALT="$\exists$">! <!-- MATH: $\lambda_{cat}$ --> <IMG WIDTH="66" HEIGHT="72" ALIGN="MIDDLE" BORDER="0" SRC="img314.gif" ALT="$\lambda_{cat}$"> / <!-- MATH: $\parallel \lambda_c - \lambda_{cat} \parallel <$ --> <IMG WIDTH="96" HEIGHT="42" ALIGN="MIDDLE" BORDER="0" SRC="img315.gif" ALT="$\parallel \lambda_c - \lambda_{cat} \parallel <$"> <!-- MATH: $\delta\lambda$ --> <IMG WIDTH="54" HEIGHT="56" ALIGN="BOTTOM" BORDER="0" SRC="img316.gif" ALT="$\delta\lambda$"></DIV> <P> with <IMG WIDTH="52" HEIGHT="72" ALIGN="MIDDLE" BORDER="0" SRC="img317.gif" ALT="$\lambda_c$">, computed estimated wavelength, <!-- MATH: $\lambda_{cat}$ --> <IMG WIDTH="66" HEIGHT="72" ALIGN="MIDDLE" BORDER="0" SRC="img318.gif" ALT="$\lambda_{cat}$">the catalog wavelength and <!-- MATH: $\delta\lambda$ --> <IMG WIDTH="54" HEIGHT="56" ALIGN="BOTTOM" BORDER="0" SRC="img319.gif" ALT="$\delta\lambda$">, a majorant of the error of the computed wavelength, taken as the distance of the closest neighbor in the line catalog or in the arc spectrum divided by a coefficient <IMG WIDTH="44" HEIGHT="54" ALIGN="BOTTOM" BORDER="0" SRC="img320.gif" ALT="$\alpha$"> which value does not exceed 1 (this parameter is controlled by the session keyword <TT>WLCLOOP(2)</TT>). <P> <BR><HR> <ADDRESS> <I>Petra Nass</I> <BR><I>1999-06-15</I> </ADDRESS> </BODY> </HTML>