<!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>Introduction</TITLE> <META NAME="description" CONTENT="Introduction"> <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="previous" HREF="node493.html"> <LINK REL="up" HREF="node493.html"> <LINK REL="next" HREF="node495.html"> </HEAD> <BODY > <!--Navigation Panel--> <A NAME="tex2html7592" HREF="node495.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="icons.gif/next_motif.gif"></A> <A NAME="tex2html7589" HREF="node493.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="icons.gif/up_motif.gif"></A> <A NAME="tex2html7585" HREF="node493.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="icons.gif/previous_motif.gif"></A> <A NAME="tex2html7591" 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="tex2html7593" HREF="node495.html">A typical reduction.</A> <B> Up:</B> <A NAME="tex2html7590" HREF="node493.html">IRSPEC REDUCTION</A> <B> Previous:</B> <A NAME="tex2html7586" HREF="node493.html">IRSPEC REDUCTION</A> <BR> <BR> <!--End of Navigation Panel--> <H1><A NAME="SECTION002910000000000000000"> </A> <A NAME="irspec-introduction"> </A> <BR> Introduction </H1> <P> IRSPEC is a cryogenically cooled grating spectrometer equipped with a relatively small (for optical CCD standards) 2D array of 62x58 pixels. It covers the 1 <IMG WIDTH="44" HEIGHT="70" ALIGN="MIDDLE" BORDER="0" SRC="img998.gif" ALT="$\mu$">m to 5 <IMG WIDTH="44" HEIGHT="70" ALIGN="MIDDLE" BORDER="0" SRC="img999.gif" ALT="$\mu$">m wavelength range and the two back-to-back gratings - #2 optimized for observations at <!-- MATH: $\lambda\le2.5$ --> <IMG WIDTH="30" HEIGHT="41" ALIGN="MIDDLE" BORDER="0" SRC="img1000.gif" ALT="$\lambda\le2.5$"> <IMG WIDTH="44" HEIGHT="70" ALIGN="MIDDLE" BORDER="0" SRC="img1001.gif" ALT="$\mu$">m and #1 for longer wavelengths - yield a dispersion of <IMG WIDTH="64" HEIGHT="54" ALIGN="BOTTOM" BORDER="0" SRC="img1002.gif" ALT="$\simeq5$"> Å/pixel in H and K (1.4-2.5 <IMG WIDTH="44" HEIGHT="70" ALIGN="MIDDLE" BORDER="0" SRC="img1003.gif" ALT="$\mu$">m), <IMG WIDTH="4" HEIGHT="21" ALIGN="BOTTOM" BORDER="0" SRC="img1004.gif" ALT="$\simeq10$"> Å/pixel in L,M (3-5 <IMG WIDTH="44" HEIGHT="70" ALIGN="MIDDLE" BORDER="0" SRC="img1005.gif" ALT="$\mu$">m) while in J (1-1.3 <IMG WIDTH="44" HEIGHT="70" ALIGN="MIDDLE" BORDER="0" SRC="img1006.gif" ALT="$\mu$">m) one can choose between <IMG WIDTH="64" HEIGHT="54" ALIGN="BOTTOM" BORDER="0" SRC="img1007.gif" ALT="$\simeq2$"> Å/pixel (grating #2 order 2) or <IMG WIDTH="10" HEIGHT="21" ALIGN="BOTTOM" BORDER="0" SRC="img1008.gif" ALT="$\simeq3.5$"> Å/pixel (grating #1 order 3). In all cases the resolving power is quite high and each frame covers a small wavelength range; obtaining complete spectra of an atmospheric window requires <IMG WIDTH="46" HEIGHT="54" ALIGN="BOTTOM" BORDER="0" SRC="img1009.gif" ALT="$\sim$">20 images at different grating positions. Along the slit the pixel size is <IMG WIDTH="10" HEIGHT="21" ALIGN="BOTTOM" BORDER="0" SRC="img1010.gif" ALT="$\simeq2.2$"> arcsec and the total, usable slit length is slightly less than 2 arcmin; small areas at the edges of the slit are vignetted. <P> Although there is no standard procedure for the observations, it is generally agreed that the most convenient strategy to subtract the strong sky emission - OH airglow up to 2.25 <IMG WIDTH="44" HEIGHT="70" ALIGN="MIDDLE" BORDER="0" SRC="img1011.gif" ALT="$\mu$">m and thermal + molecular bands beyond - is to alternatively measure the `object' and the `sky' and subtract the frames (note that the `sky' frame may also be taken with the object in another position along the slit). On chip subtraction of the sky emission - - the procedure normally used for optical CCD's - gives worse results due to the large intensity of the sky background combined with the relatively bad cosmetic quality of the infrared arrays. The object-sky telescope nodding is typically done every few minutes and one or more frames per telescope positions are produced and stored. At the end of the night, therefore, one has collected several hundred images which may also include data taken at many different wavelengths. This document describes a few procedures (commands) developed to make the handling of the many frames somewhat easier. For each command I did my best to provide you with long and exhaustive help files which are available on line. Here I just briefly describe the steps to follow to take full advantage of the commands available (remember to type SET/CONTEXT IRSPEC to access them). <P> <BR><HR> <!--Table of Child-Links--> <A NAME="CHILD_LINKS"> </A> <UL> <LI><A NAME="tex2html7594" HREF="node495.html">A typical reduction.</A> <LI><A NAME="tex2html7595" HREF="node496.html">Notes on specific commands</A> </UL> <!--End of Table of Child-Links--> <HR> <!--Navigation Panel--> <A NAME="tex2html7592" HREF="node495.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="icons.gif/next_motif.gif"></A> <A NAME="tex2html7589" HREF="node493.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="icons.gif/up_motif.gif"></A> <A NAME="tex2html7585" HREF="node493.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="icons.gif/previous_motif.gif"></A> <A NAME="tex2html7591" 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="tex2html7593" HREF="node495.html">A typical reduction.</A> <B> Up:</B> <A NAME="tex2html7590" HREF="node493.html">IRSPEC REDUCTION</A> <B> Previous:</B> <A NAME="tex2html7586" HREF="node493.html">IRSPEC REDUCTION</A> <!--End of Navigation Panel--> <ADDRESS> <I>Petra Nass</I> <BR><I>1999-06-15</I> </ADDRESS> </BODY> </HTML>
