<!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>Telescope obstruction data</TITLE> <META NAME="description" CONTENT="Telescope obstruction data"> <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="node552.html"> <LINK REL="previous" HREF="node550.html"> <LINK REL="up" HREF="node548.html"> <LINK REL="next" HREF="node552.html"> </HEAD> <BODY > <!--Navigation Panel--> <A NAME="tex2html8413" HREF="node552.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="icons.gif/next_motif.gif"></A> <A NAME="tex2html8410" HREF="node548.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="icons.gif/up_motif.gif"></A> <A NAME="tex2html8404" HREF="node550.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="icons.gif/previous_motif.gif"></A> <A NAME="tex2html8412" 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="tex2html8414" HREF="node552.html">Instrumental data</A> <B> Up:</B> <A NAME="tex2html8411" HREF="node548.html">Introduction</A> <B> Previous:</B> <A NAME="tex2html8405" HREF="node550.html">Observatory data</A> <BR> <BR> <!--End of Navigation Panel--> <H2><A NAME="SECTION003213000000000000000"> Telescope obstruction data</A> </H2> Nearly every telescope seems to have some parts of the sky that are inaccessible. Trees, mountains, and even other telescopes obscure some areas above the horizon. Furthermore, many telescopes have peculiar mountings or other mechanical limitations on where they may look. In a surprising number of cases, the inaccessible regions extend into the parts of the sky one would normally use to measure extinction stars. Such restrictions should be placed in a separate ``obstruction'' table for each telescope. <P> <BR><HR> <ADDRESS> <I>Petra Nass</I> <BR><I>1999-06-15</I> </ADDRESS> </BODY> </HTML>
