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diff --git a/src/slalib/sun67.htx/node150.html b/src/slalib/sun67.htx/node150.html new file mode 100644 index 0000000..4750c08 --- /dev/null +++ b/src/slalib/sun67.htx/node150.html @@ -0,0 +1,202 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"> +<!--Converted with LaTeX2HTML 97.1 (release) (July 13th, 1997) + 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 Lippman, Marek Rouchal, Martin Wilck and others --> +<HTML> +<HEAD> +<TITLE>SLA_POLMO - Polar Motion</TITLE> +<META NAME="description" CONTENT="SLA_POLMO - Polar Motion"> +<META NAME="keywords" CONTENT="sun67"> +<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="sun67.css"> +<LINK REL="next" HREF="node151.html"> +<LINK REL="previous" HREF="node149.html"> +<LINK REL="up" HREF="node13.html"> +<LINK REL="next" HREF="node151.html"> +</HEAD> +<BODY > +<BR> <HR> +<A NAME="tex2html1926" HREF="node151.html"> +<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next_motif.gif"></A> +<A NAME="tex2html1924" HREF="node13.html"> +<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up_motif.gif"></A> +<A NAME="tex2html1918" HREF="node149.html"> +<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="previous_motif.gif"></A> <A HREF="sun67.html#stardoccontents"><IMG ALIGN="BOTTOM" BORDER="0" + SRC="contents_motif.gif"></A> +<BR> +<B> Next:</B> <A NAME="tex2html1927" HREF="node151.html">SLA_PREBN - Precession Matrix (FK4)</A> +<BR> +<B>Up:</B> <A NAME="tex2html1925" HREF="node13.html">SUBPROGRAM SPECIFICATIONS</A> +<BR> +<B> Previous:</B> <A NAME="tex2html1919" HREF="node149.html">SLA_PM - Proper Motion</A> +<BR> <HR> <P> +<P><!--End of Navigation Panel--> +<H2><A NAME="SECTION0004137000000000000000">SLA_POLMO - Polar Motion</A> +<A NAME="xref_SLA_POLMO"> </A><A NAME="SLA_POLMO"> </A> +</H2> + <DL> +<DT><STRONG>ACTION:</STRONG> +<DD>Polar motion: correct site longitude and latitude for polar +motion and calculate azimuth difference between celestial and + terrestrial poles. +<P> <DT><STRONG>CALL:</STRONG> +<DD><TT>CALL sla_POLMO (ELONGM, PHIM, XP, YP, ELONG, PHI, DAZ)</TT> +<P> </DL> +<P> <DL> +<DT><STRONG>GIVEN:</STRONG> +<DD> +<BR> +<TABLE CELLPADDING=3> +<TR VALIGN="TOP"><TD ALIGN="LEFT"><EM>ELONGM</EM></TD> +<TH ALIGN="LEFT"><B>D</B></TH> +<TD ALIGN="LEFT" NOWRAP>mean longitude of the site (radians, east +ve)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="LEFT"><EM>PHIM</EM></TD> +<TD ALIGN="LEFT"><B>D</B></TD> +<TD ALIGN="LEFT" NOWRAP>mean geodetic latitude of the site (radians)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="LEFT"><EM>XP</EM></TD> +<TD ALIGN="LEFT"><B>D</B></TD> +<TD ALIGN="LEFT" NOWRAP>polar motion <I>x</I>-coordinate (radians)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="LEFT"><EM>YP</EM></TD> +<TD ALIGN="LEFT"><B>D</B></TD> +<TD ALIGN="LEFT" NOWRAP>polar motion <I>y</I>-coordinate (radians)</TD> +</TR> +</TABLE></DL> +<P> <DL> +<DT><STRONG>RETURNED:</STRONG> +<DD> +<BR> +<TABLE CELLPADDING=3> +<TR VALIGN="TOP"><TD ALIGN="LEFT"><EM>ELONG</EM></TD> +<TH ALIGN="LEFT"><B>D</B></TH> +<TD ALIGN="LEFT" NOWRAP>true longitude of the site (radians, east +ve)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="LEFT"><EM>PHI</EM></TD> +<TD ALIGN="LEFT"><B>D</B></TD> +<TD ALIGN="LEFT" NOWRAP>true geodetic latitude of the site (radians)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="LEFT"><EM>DAZ</EM></TD> +<TD ALIGN="LEFT"><B>D</B></TD> +<TD ALIGN="LEFT" NOWRAP>azimuth correction (terrestrial-celestial, radians)</TD> +</TR> +</TABLE></DL> +<P> <DL> +<DT><STRONG>NOTES:</STRONG> +<DD><DL COMPACT> +<DT>1. +<DD>``Mean'' longitude and latitude are the (fixed) values for the +site's location with respect to the IERS terrestrial reference +frame; the latitude is geodetic. TAKE CARE WITH THE LONGITUDE + SIGN CONVENTION. The longitudes used by the present routine + are east-positive, in accordance with geographical convention + (and right-handed). In particular, note that the longitudes + returned by the sla_OBS routine are west-positive, following + astronomical usage, and must be reversed in sign before use in + the present routine. +<DT>2. +<DD>XP and YP are the (changing) coordinates of the Celestial + Ephemeris Pole with respect to the IERS Reference Pole. + XP is positive along the meridian at longitude <IMG WIDTH="18" HEIGHT="14" ALIGN="BOTTOM" BORDER="0" + SRC="img1.gif" + ALT="$0^{\circ}$">, and YP is positive along the meridian at longitude + <IMG WIDTH="34" HEIGHT="14" ALIGN="BOTTOM" BORDER="0" + SRC="img139.gif" + ALT="$270^\circ$"> (<I>i.e.</I> <IMG WIDTH="26" HEIGHT="14" ALIGN="BOTTOM" BORDER="0" + SRC="img22.gif" + ALT="$90^{\circ}$"> west). Values for XP,YP can + be obtained from IERS circulars and equivalent publications; + the maximum amplitude observed so far is about + <IMG WIDTH="23" HEIGHT="18" ALIGN="BOTTOM" BORDER="0" + SRC="img32.gif" + ALT="$0\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.3$"> . +<DT>3. +<DD>``True'' longitude and latitude are the (moving) values for + the site's location with respect to the celestial ephemeris + pole and the meridian which corresponds to the Greenwich + apparent sidereal time. The true longitude and latitude + link the terrestrial coordinates with the standard celestial + models (for precession, nutation, sidereal time <I>etc</I>). +<DT>4. +<DD>The azimuths produced by sla_AOP and sla_AOPQK are with + respect to due north as defined by the Celestial Ephemeris + Pole, and can therefore be called ``celestial azimuths''. + However, a telescope fixed to the Earth measures azimuth + essentially with respect to due north as defined by the + IERS Reference Pole, and can therefore be called ``terrestrial + azimuth''. Uncorrected, this would manifest itself as a + changing ``azimuth zero-point error''. The value DAZ is the + correction to be added to a celestial azimuth to produce + a terrestrial azimuth. +<DT>5. +<DD>The present routine is rigorous. For most practical + purposes, the following simplified formulae provide an + adequate approximation: <BR> +<BR> +<BR> + <TABLE CELLPADDING=3> +<TR VALIGN="TOP"><TD ALIGN="LEFT" NOWRAP><TT>ELONG</TT></TD> +<TD ALIGN="LEFT" NOWRAP><TT>=</TT></TD> +<TD ALIGN="LEFT" NOWRAP><TT>ELONGM+XP*COS(ELONGM)-YP*SIN(ELONGM)</TT></TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="LEFT" NOWRAP><TT>PHI </TT></TD> +<TD ALIGN="LEFT" NOWRAP><TT>=</TT></TD> +<TD ALIGN="LEFT" NOWRAP><TT>PHIM+(XP*SIN(ELONGM)+YP*COS(ELONGM))*TAN(PHIM)</TT></TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="LEFT" NOWRAP><TT>DAZ </TT></TD> +<TD ALIGN="LEFT" NOWRAP><TT>=</TT></TD> +<TD ALIGN="LEFT" NOWRAP><TT>-SQRT(XP*XP+YP*YP)*COS(ELONGM-ATAN2(XP,YP))/COS(PHIM)</TT></TD> +</TR> +</TABLE> <BR> +<BR> +<BR> +An alternative formulation for DAZ is: +<BR> +<BR> +<BR> + <TABLE CELLPADDING=3> +<TR VALIGN="TOP"><TD ALIGN="LEFT" NOWRAP><TT>X </TT></TD> +<TD ALIGN="LEFT" NOWRAP><TT>=</TT></TD> +<TD ALIGN="LEFT" NOWRAP><TT>COS(ELONGM)*COS(PHIM)</TT></TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="LEFT" NOWRAP><TT>Y </TT></TD> +<TD ALIGN="LEFT" NOWRAP><TT>=</TT></TD> +<TD ALIGN="LEFT" NOWRAP><TT>SIN(ELONGM)*COS(PHIM)</TT></TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="LEFT" NOWRAP><TT>DAZ</TT></TD> +<TD ALIGN="LEFT" NOWRAP><TT>=</TT></TD> +<TD ALIGN="LEFT" NOWRAP><TT>ATAN2(-X*YP-Y*XP,X*X+Y*Y)</TT></TD> +</TR> +</TABLE></DL></DL> +<P> <DL> +<DT><STRONG>REFERENCE:</STRONG> +<DD>Seidelmann, P.K. (ed), 1992. <I>Explanatory +Supplement to the Astronomical Almanac,</I> ISBN 0-935702-68-7, + sections 3.27, 4.25, 4.52. + </DL> +<BR> <HR> +<A NAME="tex2html1926" HREF="node151.html"> +<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next_motif.gif"></A> +<A NAME="tex2html1924" HREF="node13.html"> +<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up_motif.gif"></A> +<A NAME="tex2html1918" HREF="node149.html"> +<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="previous_motif.gif"></A> <A HREF="sun67.html#stardoccontents"><IMG ALIGN="BOTTOM" BORDER="0" + SRC="contents_motif.gif"></A> +<BR> +<B> Next:</B> <A NAME="tex2html1927" HREF="node151.html">SLA_PREBN - Precession Matrix (FK4)</A> +<BR> +<B>Up:</B> <A NAME="tex2html1925" HREF="node13.html">SUBPROGRAM SPECIFICATIONS</A> +<BR> +<B> Previous:</B> <A NAME="tex2html1919" HREF="node149.html">SLA_PM - Proper Motion</A> +<BR> <HR> <P> +<P><!--End of Navigation Panel--> +<ADDRESS> +<I>SLALIB --- Positional Astronomy Library<BR>Starlink User Note 67<BR>P. T. Wallace<BR>12 October 1999<BR>E-mail:ptw@star.rl.ac.uk</I> +</ADDRESS> +</BODY> +</HTML> |