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<H2><A NAME="SECTION0004116000000000000000">SLA_MAPQKZ - Quick Mean-Appt, no PM <I>etc.</I></A>
<A NAME="xref_SLA_MAPQKZ"> </A><A NAME="SLA_MAPQKZ"> </A>
</H2>
<DL>
<DT><STRONG>ACTION:</STRONG>
<DD>Quick mean to apparent place: transform a star <IMG WIDTH="42" HEIGHT="29" ALIGN="MIDDLE" BORDER="0"
SRC="img3.gif"
ALT="$[\,\alpha,\delta\,]$"> from
mean place to geocentric apparent place, given the
star-independent parameters, and assuming zero parallax
and FK5 proper motion.
The reference frames and timescales used are post IAU 1976.
<P> <DT><STRONG>CALL:</STRONG>
<DD><TT>CALL sla_MAPQKZ (RM, DM, AMPRMS, RA, DA)</TT>
<P> </DL>
<P> <DL>
<DT><STRONG>GIVEN:</STRONG>
<DD>
<BR>
<TABLE CELLPADDING=3>
<TR VALIGN="TOP"><TD ALIGN="LEFT"><EM>RM,DM</EM></TD>
<TH ALIGN="LEFT"><B>D</B></TH>
<TD ALIGN="LEFT" NOWRAP>mean <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>AMPRMS</EM></TD>
<TD ALIGN="LEFT"><B>D(21)</B></TD>
<TD ALIGN="LEFT" NOWRAP>star-independent mean-to-apparent parameters:</TD>
</TR>
<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(1)</TD>
<TD></TD>
<TD ALIGN="LEFT" NOWRAP>time interval for proper motion (Julian years)</TD>
</TR>
<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(2-4)</TD>
<TD></TD>
<TD ALIGN="LEFT" NOWRAP>barycentric position of the Earth (AU)</TD>
</TR>
<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(5-7)</TD>
<TD></TD>
<TD ALIGN="LEFT" NOWRAP>heliocentric direction of the Earth (unit vector)</TD>
</TR>
<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(8)</TD>
<TD></TD>
<TD ALIGN="LEFT" NOWRAP>(gravitational radius of
Sun)<IMG WIDTH="31" HEIGHT="29" ALIGN="MIDDLE" BORDER="0"
SRC="img16.gif"
ALT="$\times 2 / $">(Sun-Earth distance)</TD>
</TR>
<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(9-11)</TD>
<TD></TD>
<TD ALIGN="LEFT" NOWRAP><B>v</B>: barycentric Earth velocity in units of c</TD>
</TR>
<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(12)</TD>
<TD></TD>
<TD ALIGN="LEFT" NOWRAP><IMG WIDTH="72" HEIGHT="45" ALIGN="MIDDLE" BORDER="0"
SRC="img17.gif"
ALT="$\sqrt{1-\left\vert\mbox{\bf v}\right\vert^2}$"></TD>
</TR>
<TR VALIGN="TOP"><TD ALIGN="CENTER" NOWRAP COLSPAN=1>(13-21)</TD>
<TD></TD>
<TD ALIGN="LEFT" NOWRAP>precession/nutation <IMG WIDTH="39" HEIGHT="25" ALIGN="MIDDLE" BORDER="0"
SRC="img18.gif"
ALT="$3\times3$"> matrix</TD>
</TR>
</TABLE></DL>
<P> <DL>
<DT><STRONG>RETURNED:</STRONG>
<DD>
<BR>
<TABLE CELLPADDING=3>
<TR VALIGN="TOP"><TD ALIGN="LEFT"><EM>RA,DA</EM></TD>
<TH ALIGN="LEFT"><B>D</B></TH>
<TD ALIGN="LEFT" NOWRAP>apparent <IMG WIDTH="42" HEIGHT="29" ALIGN="MIDDLE" BORDER="0"
SRC="img3.gif"
ALT="$[\,\alpha,\delta\,]$"> (radians)</TD>
</TR>
</TABLE></DL>
<P> <DL>
<DT><STRONG>NOTES:</STRONG>
<DD><DL COMPACT>
<DT>1.
<DD>Use of this routine is appropriate when efficiency is important
and where many star positions, all with parallax and proper
motion either zero or already allowed for, and all referred to
the same equator and equinox, are to be transformed for one
epoch. The star-independent parameters can be obtained by
calling the sla_MAPPA routine.
<DT>2.
<DD>The corresponding routine for the case of non-zero parallax
and FK5 proper motion is sla_MAPQK.
<DT>3.
<DD>The vectors AMPRMS(2-4) and AMPRMS(5-7) are referred to the
mean equinox and equator of epoch EQ.
<DT>4.
<DD>Strictly speaking, the routine is not valid for solar-system
sources, though the error will usually be extremely small.
However, to prevent gross errors in the case where the
position of the Sun is specified, the gravitational
deflection term is restrained within about <IMG WIDTH="33" HEIGHT="18" ALIGN="BOTTOM" BORDER="0"
SRC="img124.gif"
ALT="$920\hspace{-0.05em}^{'\hspace{-0.1em}'}$"> of the
centre of the Sun's disc. The term has a maximum value of
about
<IMG WIDTH="31" HEIGHT="18" ALIGN="BOTTOM" BORDER="0"
SRC="img125.gif"
ALT="$1\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.85$"> at this radius, and decreases to zero as
the centre of the disc is approached.
</DL></DL>
<P> <DL>
<DT><STRONG>REFERENCES:</STRONG>
<DD><DL COMPACT>
<DT>1.
<DD>1984 <I>Astronomical Almanac</I>, pp B39-B41.
<DT>2.
<DD>Lederle & Schwan, 1984. <I>Astr.Astrophys.</I> <B>134</B>, 1-6.
</DL></DL>
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<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>
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