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diff --git a/src/slalib/sun67.htx/node23.html b/src/slalib/sun67.htx/node23.html new file mode 100644 index 0000000..dfb0e24 --- /dev/null +++ b/src/slalib/sun67.htx/node23.html @@ -0,0 +1,278 @@ +<!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_AOPQK - Quick Appt-to-Observed</TITLE> +<META NAME="description" CONTENT="SLA_AOPQK - Quick Appt-to-Observed"> +<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="node24.html"> +<LINK REL="previous" HREF="node22.html"> +<LINK REL="up" HREF="node13.html"> +<LINK REL="next" HREF="node24.html"> +</HEAD> +<BODY > +<BR> <HR> +<A NAME="tex2html656" HREF="node24.html"> +<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next_motif.gif"></A> +<A NAME="tex2html654" HREF="node13.html"> +<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up_motif.gif"></A> +<A NAME="tex2html648" HREF="node22.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="tex2html657" HREF="node24.html">SLA_ATMDSP - Atmospheric Dispersion</A> +<BR> +<B>Up:</B> <A NAME="tex2html655" HREF="node13.html">SUBPROGRAM SPECIFICATIONS</A> +<BR> +<B> Previous:</B> <A NAME="tex2html649" HREF="node22.html">SLA_AOPPAT - Update Appt-to-Obs Parameters</A> +<BR> <HR> <P> +<P><!--End of Navigation Panel--> +<H2><A NAME="SECTION000410000000000000000">SLA_AOPQK - Quick Appt-to-Observed</A> +<A NAME="xref_SLA_AOPQK"> </A><A NAME="SLA_AOPQK"> </A> +</H2> + <DL> +<DT><STRONG>ACTION:</STRONG> +<DD>Quick apparent to observed place (but see Note 8, below). +<DT><STRONG>CALL:</STRONG> +<DD><TT>CALL sla_AOPQK (RAP, DAP, AOPRMS, AOB, ZOB, HOB, DOB, ROB)</TT> +<P> </DL> +<P> <DL> +<DT><STRONG>GIVEN:</STRONG> +<DD> +<BR> +<TABLE CELLPADDING=3> +<TR VALIGN="TOP"><TD ALIGN="LEFT"><EM>RAP,DAP</EM></TD> +<TH ALIGN="LEFT"><B>D</B></TH> +<TD ALIGN="LEFT" NOWRAP>geocentric apparent <IMG WIDTH="42" HEIGHT="29" ALIGN="MIDDLE" BORDER="0" + SRC="img3.gif" + ALT="$[\,\alpha,\delta\,]$"> (radians)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="LEFT"><EM>AOPRMS</EM></TD> +<TD ALIGN="LEFT"><B>D(14)</B></TD> +<TD ALIGN="LEFT" NOWRAP>star-independent apparent-to-observed parameters:</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(1)</TD> +<TD></TD> +<TD ALIGN="LEFT" NOWRAP>geodetic latitude (radians)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(2,3)</TD> +<TD></TD> +<TD ALIGN="LEFT" NOWRAP>sine and cosine of geodetic latitude</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(4)</TD> +<TD></TD> +<TD ALIGN="LEFT" NOWRAP>magnitude of diurnal aberration vector</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(5)</TD> +<TD></TD> +<TD ALIGN="LEFT" NOWRAP>height (metres)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(6)</TD> +<TD></TD> +<TD ALIGN="LEFT" NOWRAP>ambient temperature (degrees K)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(7)</TD> +<TD></TD> +<TD ALIGN="LEFT" NOWRAP>pressure (mB)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(8)</TD> +<TD></TD> +<TD ALIGN="LEFT" NOWRAP>relative humidity (0-1)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(9)</TD> +<TD></TD> +<TD ALIGN="LEFT" NOWRAP>wavelength (<IMG WIDTH="26" HEIGHT="25" ALIGN="MIDDLE" BORDER="0" + SRC="img21.gif" + ALT="$\mu{\rm m}$">)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(10)</TD> +<TD></TD> +<TD ALIGN="LEFT" NOWRAP>lapse rate (degrees K per metre)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(11,12)</TD> +<TD></TD> +<TD ALIGN="LEFT" NOWRAP>refraction constants A and B (radians)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(13)</TD> +<TD></TD> +<TD ALIGN="LEFT" NOWRAP>longitude + eqn of equinoxes + +``sidereal <IMG WIDTH="16" HEIGHT="13" ALIGN="BOTTOM" BORDER="0" + SRC="img19.gif" + ALT="$\Delta$">UT'' (radians)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(14)</TD> +<TD></TD> +<TD ALIGN="LEFT" NOWRAP>local apparent sidereal time (radians)</TD> +</TR> +</TABLE></DL> +<P> <DL> +<DT><STRONG>RETURNED:</STRONG> +<DD> +<BR> +<TABLE CELLPADDING=3> +<TR VALIGN="TOP"><TD ALIGN="LEFT"><EM>AOB</EM></TD> +<TH ALIGN="LEFT"><B>D</B></TH> +<TD ALIGN="LEFT" NOWRAP>observed azimuth (radians: N=0, E=<IMG WIDTH="26" HEIGHT="14" ALIGN="BOTTOM" BORDER="0" + SRC="img22.gif" + ALT="$90^{\circ}$">)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="LEFT"><EM>ZOB</EM></TD> +<TD ALIGN="LEFT"><B>D</B></TD> +<TD ALIGN="LEFT" NOWRAP>observed zenith distance (radians)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="LEFT"><EM>HOB</EM></TD> +<TD ALIGN="LEFT"><B>D</B></TD> +<TD ALIGN="LEFT" NOWRAP>observed Hour Angle (radians)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="LEFT"><EM>DOB</EM></TD> +<TD ALIGN="LEFT"><B>D</B></TD> +<TD ALIGN="LEFT" NOWRAP>observed Declination (radians)</TD> +</TR> +<TR VALIGN="TOP"><TD ALIGN="LEFT"><EM>ROB</EM></TD> +<TD ALIGN="LEFT"><B>D</B></TD> +<TD ALIGN="LEFT" NOWRAP>observed Right Ascension (radians)</TD> +</TR> +</TABLE></DL> +<P> <DL> +<DT><STRONG>NOTES:</STRONG> +<DD><DL COMPACT> +<DT>1. +<DD>This routine returns zenith distance rather than elevation +in order to reflect the fact that no allowance is made for +depression of the horizon. + <DT>2. +<DD>The accuracy of the result is limited by the corrections for + refraction. Providing the meteorological parameters are + known accurately and there are no gross local effects, the + predicted azimuth and elevation should be within about +<P> <IMG WIDTH="23" HEIGHT="18" ALIGN="BOTTOM" BORDER="0" + SRC="img25.gif" + ALT="$0\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.1$"> for <IMG WIDTH="56" HEIGHT="27" ALIGN="MIDDLE" BORDER="0" + SRC="img26.gif" + ALT="$\zeta<70^{\circ}$">. Even + at a topocentric zenith distance of + <IMG WIDTH="26" HEIGHT="14" ALIGN="BOTTOM" BORDER="0" + SRC="img22.gif" + ALT="$90^{\circ}$">, the accuracy in elevation should be better than + 1 arcminute; useful results are available for a further + <IMG WIDTH="18" HEIGHT="14" ALIGN="BOTTOM" BORDER="0" + SRC="img27.gif" + ALT="$3^{\circ}$">, beyond which the sla_REFRO routine returns a + fixed value of the refraction. The complementary + routines sla_AOP (or sla_AOPQK) and sla_OAP (or sla_OAPQK) + are self-consistent to better than 1 microarcsecond all over + the celestial sphere. + <DT>3. +<DD>It is advisable to take great care with units, as even + unlikely values of the input parameters are accepted and + processed in accordance with the models used. + <DT>4. +<DD><I>Apparent</I> <IMG WIDTH="42" HEIGHT="29" ALIGN="MIDDLE" BORDER="0" + SRC="img3.gif" + ALT="$[\,\alpha,\delta\,]$"> means the geocentric apparent right ascension + and declination, which is obtained from a catalogue mean place + by allowing for space motion, parallax, precession, nutation, + annual aberration, and the Sun's gravitational lens effect. For + star positions in the FK5 system (<I>i.e.</I> J2000), these effects can + be applied by means of the sla_MAP <I>etc.</I> routines. Starting from + other mean place systems, additional transformations will be + needed; for example, FK4 (<I>i.e.</I> B1950) mean places would first + have to be converted to FK5, which can be done with the + sla_FK425 <I>etc.</I> routines. + <DT>5. +<DD><I>Observed</I> <IMG WIDTH="66" HEIGHT="29" ALIGN="MIDDLE" BORDER="0" + SRC="img28.gif" + ALT="$[\,Az,El~]$"> means the position that would be seen by a + perfect theodolite located at the observer. This is obtained + from the geocentric apparent <IMG WIDTH="42" HEIGHT="29" ALIGN="MIDDLE" BORDER="0" + SRC="img3.gif" + ALT="$[\,\alpha,\delta\,]$"> by allowing for Earth + orientation and diurnal aberration, rotating from equator + to horizon coordinates, and then adjusting for refraction. + The <IMG WIDTH="41" HEIGHT="29" ALIGN="MIDDLE" BORDER="0" + SRC="img29.gif" + ALT="$[\,h,\delta\,]$"> is obtained by rotating back into equatorial + coordinates, using the geodetic latitude corrected for polar + motion, and is the position that would be seen by a perfect + equatorial located at the observer and with its polar axis + aligned to the Earth's axis of rotation (<I>n.b.</I> not to the + refracted pole). Finally, the <IMG WIDTH="13" HEIGHT="14" ALIGN="BOTTOM" BORDER="0" + SRC="img24.gif" + ALT="$\alpha$"> is obtained by subtracting + the <I>h</I> from the local apparent ST. + <DT>6. +<DD>To predict the required setting of a real telescope, the + observed place produced by this routine would have to be + adjusted for the tilt of the azimuth or polar axis of the + mounting (with appropriate corrections for mount flexures), + for non-perpendicularity between the mounting axes, for the + position of the rotator axis and the pointing axis relative + to it, for tube flexure, for gear and encoder errors, and + finally for encoder zero points. Some telescopes would, of + course, exhibit other properties which would need to be + accounted for at the appropriate point in the sequence. + <DT>7. +<DD>The star-independent apparent-to-observed-place parameters + in AOPRMS may be computed by means of the sla_AOPPA routine. + If nothing has changed significantly except the time, the + sla_AOPPAT routine may be used to perform the requisite + partial recomputation of AOPRMS. + <DT>8. +<DD>The ``sidereal <IMG WIDTH="16" HEIGHT="13" ALIGN="BOTTOM" BORDER="0" + SRC="img19.gif" + ALT="$\Delta$">UT'' which forms part of AOPRMS(13) + is UT1-UTC converted from solar to + sidereal seconds and expressed in radians. + <DT>9. +<DD>At zenith distances beyond about <IMG WIDTH="26" HEIGHT="14" ALIGN="BOTTOM" BORDER="0" + SRC="img33.gif" + ALT="$76^\circ$">, the need for + special care with the corrections for refraction causes a + marked increase in execution time. Moreover, the effect + gets worse with increasing zenith distance. Adroit + programming in the calling application may allow the + problem to be reduced. Prepare an alternative AOPRMS array, + computed for zero air-pressure; this will disable the + refraction corrections and cause rapid execution. Using + this AOPRMS array, a preliminary call to the present routine + will, depending on the application, produce a rough position + which may be enough to establish whether the full, slow + calculation (using the real AOPRMS array) is worthwhile. + For example, there would be no need for the full calculation + if the preliminary call had already established that the + source was well below the elevation limits for a particular + telescope. + <DT>10. +<DD>The azimuths <I>etc.</I> used by the present routine are with + respect to the celestial pole. Corrections to the terrestrial pole + can be computed using sla_POLMO. + </DL></DL> +<BR> <HR> +<A NAME="tex2html656" HREF="node24.html"> +<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next_motif.gif"></A> +<A NAME="tex2html654" HREF="node13.html"> +<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up_motif.gif"></A> +<A NAME="tex2html648" HREF="node22.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="tex2html657" HREF="node24.html">SLA_ATMDSP - Atmospheric Dispersion</A> +<BR> +<B>Up:</B> <A NAME="tex2html655" HREF="node13.html">SUBPROGRAM SPECIFICATIONS</A> +<BR> +<B> Previous:</B> <A NAME="tex2html649" HREF="node22.html">SLA_AOPPAT - Update Appt-to-Obs Parameters</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> |