<!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>Column label: LON</TITLE> <META NAME="description" CONTENT="Column label: LON"> <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="node573.html"> <LINK REL="previous" HREF="node571.html"> <LINK REL="up" HREF="node569.html"> <LINK REL="next" HREF="node573.html"> </HEAD> <BODY > <!--Navigation Panel--> <A NAME="tex2html8669" HREF="node573.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="icons.gif/next_motif.gif"></A> <A NAME="tex2html8666" HREF="node569.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="icons.gif/up_motif.gif"></A> <A NAME="tex2html8660" HREF="node571.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="icons.gif/previous_motif.gif"></A> <A NAME="tex2html8668" 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="tex2html8670" HREF="node573.html">Column label: LAT</A> <B> Up:</B> <A NAME="tex2html8667" HREF="node569.html">Permanent telescope parameters</A> <B> Previous:</B> <A NAME="tex2html8661" HREF="node571.html">Column label: DIAM</A> <BR> <BR> <!--End of Navigation Panel--> <H2><A NAME="SECTION003233000000000000000"> Column label: LON</A> </H2> <P> This is the longitude of the telescope, measured in decimal degrees <I>east</I> from Greenwich. Note that the sign convention for longitudes changed in 1984! The older versions of the Astronomical Almanac gave <I>west</I> longitudes. For photometric data reduction, an accuracy of about 0.003 degree (about 20 arcsec) is required. Current volumes of the Astronomical Almanac give positions to 0.1 arc minute, which is adequate for our purposes. <P> Astrometric observations, including occultation timings that may be measured with photometric equipment, require much better accuracy. You can find precise positions of telescopes in the pre-1984 volumes of the Astronomical Almanac. You should try to provide as accurate a value as possible. <P> <BR><HR> <ADDRESS> <I>Petra Nass</I> <BR><I>1999-06-15</I> </ADDRESS> </BODY> </HTML>
