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| author | Joseph Hunkeler <jhunkeler@gmail.com> | 2015-03-04 21:21:30 -0500 |
|---|---|---|
| committer | Joseph Hunkeler <jhunkeler@gmail.com> | 2015-03-04 21:21:30 -0500 |
| commit | d54fe7c1f704a63824c5bfa0ece65245572e9b27 (patch) | |
| tree | afc52015ffc2c74e0266653eecef1c8ef8ba5d91 /src/slalib/sun67.htx/node215.html | |
| download | calfuse-d54fe7c1f704a63824c5bfa0ece65245572e9b27.tar.gz | |
Initial commit
Diffstat (limited to 'src/slalib/sun67.htx/node215.html')
| -rw-r--r-- | src/slalib/sun67.htx/node215.html | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/src/slalib/sun67.htx/node215.html b/src/slalib/sun67.htx/node215.html new file mode 100644 index 0000000..020487b --- /dev/null +++ b/src/slalib/sun67.htx/node215.html @@ -0,0 +1,87 @@ +<!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>Efficiency considerations</TITLE> +<META NAME="description" CONTENT="Efficiency considerations"> +<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="previous" HREF="node214.html"> +<LINK REL="up" HREF="node213.html"> +<LINK REL="next" HREF="node216.html"> +</HEAD> +<BODY > +<BR> <HR> +<A NAME="tex2html2601" HREF="node216.html"> +<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next_motif.gif"></A> +<A NAME="tex2html2599" HREF="node213.html"> +<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up_motif.gif"></A> +<A NAME="tex2html2595" HREF="node214.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="tex2html2602" HREF="node216.html">The Hipparcos Catalogue and the ICRS</A> +<BR> +<B>Up:</B> <A NAME="tex2html2600" HREF="node213.html">Apparent Place to Observed Place</A> +<BR> +<B> Previous:</B> <A NAME="tex2html2596" HREF="node214.html">Refraction</A> +<BR> <HR> <P> +<P><!--End of Navigation Panel--> +<H3><A NAME="SECTION000513200000000000000"> +Efficiency considerations</A> +</H3> +The complete apparent place to observed place transformation +can be carried out by calling +sla_AOP. +For improved efficiency +in cases of more than one star or a sequence of times, the +target-independent calculations can be done once by +calling +sla_AOPPA, +the time can be updated by calling +sla_AOPPAT, +and +sla_AOPQK +can then be used to perform the +apparent-to-observed transformation. The reverse transformation +is available through +sla_OAP +and +sla_OAPQK. +(<I>n.b.</I> These routines use accurate but computationally-expensive +refraction algorithms for zenith distances beyond about <IMG WIDTH="26" HEIGHT="14" ALIGN="BOTTOM" BORDER="0" + SRC="img33.gif" + ALT="$76^\circ$">.For many purposes, in-line code tailored to the accuracy requirements +of the application will be preferable, for example ignoring UT1-UTC, +omitting diurnal aberration and using +sla_REFZ +to apply the refraction.) +<P> +<BR> <HR> +<A NAME="tex2html2601" HREF="node216.html"> +<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next_motif.gif"></A> +<A NAME="tex2html2599" HREF="node213.html"> +<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up_motif.gif"></A> +<A NAME="tex2html2595" HREF="node214.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="tex2html2602" HREF="node216.html">The Hipparcos Catalogue and the ICRS</A> +<BR> +<B>Up:</B> <A NAME="tex2html2600" HREF="node213.html">Apparent Place to Observed Place</A> +<BR> +<B> Previous:</B> <A NAME="tex2html2596" HREF="node214.html">Refraction</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> |