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<H3><A NAME="SECTION003673100000000000000">
Line search and interactive identification</A>
</H3>
<P>
The detection of arc lines in the wavelength calibration frame
<!-- MATH: $\fbox{{\small \tt WLC}}$ -->
<IMG
WIDTH="45" HEIGHT="26" ALIGN="BOTTOM" BORDER="0"
SRC="img1359.gif"
ALT="\fbox{{\small \tt WLC}}">.bdf
(<B>wlc</B>) for all slitlets selected in
<!-- MATH: $\fbox{{\small \tt MOS}}$ -->
<IMG
WIDTH="45" HEIGHT="26" ALIGN="BOTTOM" BORDER="0"
SRC="img1360.gif"
ALT="\fbox{{\small \tt MOS}}">.tbl (<B>mos</B>) is done by
<P>
<BR>
<BR>
Midas
...> <TT>SEARCH/MOS</TT>
<P>
<BR>
<BR>
This command will take the slitlets' limits from
<!-- MATH: $\fbox{{\small \tt MOS}}$ -->
<IMG
WIDTH="45" HEIGHT="26" ALIGN="BOTTOM" BORDER="0"
SRC="img1361.gif"
ALT="\fbox{{\small \tt MOS}}">.tbl
and the
eventual stepping and binning factor from
<!-- MATH: $\fbox{{\small \tt YBIN}}$ -->
<IMG
WIDTH="56" HEIGHT="26" ALIGN="BOTTOM" BORDER="0"
SRC="img1362.gif"
ALT="\fbox{{\small \tt YBIN}}">
(<B>3,3</B>).
In all CCD rows
of
<!-- MATH: $\fbox{{\small \tt WLC}}$ -->
<IMG
WIDTH="45" HEIGHT="26" ALIGN="BOTTOM" BORDER="0"
SRC="img1363.gif"
ALT="\fbox{{\small \tt WLC}}">.bdf that are
selected by these parameters it will look for intensities above the chosen
threshold when comparing to the median intensity over a chosen window
(threshold and window are defined by
<!-- MATH: $\fbox{{\small \tt SEAPAR}}$ -->
<IMG
WIDTH="77" HEIGHT="26" ALIGN="BOTTOM" BORDER="0"
SRC="img1364.gif"
ALT="\fbox{{\small \tt SEAPAR}}">
(<B>200,5</B>)).
Any lines detected this
way will be centered by
<!-- MATH: $\fbox{{\small \tt CENTMET}}$ -->
<IMG
WIDTH="87" HEIGHT="26" ALIGN="BOTTOM" BORDER="0"
SRC="img1365.gif"
ALT="\fbox{{\small \tt CENTMET}}">
(<B>GRAVITY</B>) and
stored in
<!-- MATH: $\fbox{{\small \tt LINPOS}}$ -->
<IMG
WIDTH="77" HEIGHT="26" ALIGN="BOTTOM" BORDER="0"
SRC="img1366.gif"
ALT="\fbox{{\small \tt LINPOS}}">.tbl (<B>linpos</B>).
<P><P>
<BR>
<P>
<TABLE CELLPADDING=3 BORDER="1">
<TR><TD ALIGN="LEFT"><TT> :X</TT></TD>
<TD ALIGN="LEFT">x-position of line (world coordinates)</TD>
</TR>
<TR><TD ALIGN="LEFT"><TT> :Y</TT></TD>
<TD ALIGN="LEFT">y-position of line (world coordinates)</TD>
</TR>
<TR><TD ALIGN="LEFT"><TT> :PEAK</TT></TD>
<TD ALIGN="LEFT">maximum intensity of line</TD>
</TR>
<TR><TD ALIGN="LEFT"><TT> :SLIT</TT></TD>
<TD ALIGN="LEFT">number of slitlet</TD>
</TR>
</TABLE>
<BR>
<BR>
<BR>
<BR>
<P>
With
<P>
<BR>
<BR>
Midas
...> <TT>LINPLOT/MOS</TT>
<P>
<BR>
<BR>
you will get a plot of the x-positions of all found arc lines versus the CCD
rows. With
<P>
<BR>
<BR>
Midas
...> <TT>LINPLOT/MOS 1 3</TT>
<P>
<BR>
<BR>
you will get a plot of the first CCD row of slitlet 3 for which line positions
are stored in
<!-- MATH: $\fbox{{\small \tt LINPOS}}$ -->
<IMG
WIDTH="77" HEIGHT="26" ALIGN="BOTTOM" BORDER="0"
SRC="img1367.gif"
ALT="\fbox{{\small \tt LINPOS}}">.tbl. The detected lines are marked in the plot.
<P>
If you do not know the central wavelength and mean dispersion of the grism
you used you have to identify at least two arc lines in any row of any slitlet.
<P>
<BR>
<BR>
Midas
...> <TT>IDENTIFY/MOS</TT>
<P>
<BR>
<BR>
The row, in which the lines shall be identified, is read from
<!-- MATH: $\fbox{{\small \tt YSTART}}$ -->
<IMG
WIDTH="77" HEIGHT="26" ALIGN="BOTTOM" BORDER="0"
SRC="img1368.gif"
ALT="\fbox{{\small \tt YSTART}}">(<B>0</B>). If you do not provide any number either there or on the command line,
the program will take the first CCD row that has been scanned.
As frame it will use
<!-- MATH: $\fbox{{\small \tt WLC}}$ -->
<IMG
WIDTH="45" HEIGHT="26" ALIGN="BOTTOM" BORDER="0"
SRC="img1369.gif"
ALT="\fbox{{\small \tt WLC}}">.bdf.
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<ADDRESS>
<I>Petra Nass</I>
<BR><I>1999-06-15</I>
</ADDRESS>
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