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<H3><A NAME="SECTION003042400000000000000">
Wavelength calibration</A>
</H3>
After having identified a few lines with the Identify window, click the
<!-- MATH: $\fbox{\tt Calibrate}$ -->
<IMG
WIDTH="117" HEIGHT="27" ALIGN="BOTTOM" BORDER="0"
SRC="img1084.gif"
ALT="\fbox{\tt Calibrate}">
button in the Main window. The Wavelength
Calibration window appears. The associated parameters can be set and a
preliminary wavelength calibration is performed on the central row
<TT>YSTART</TT> by clicking on
<!-- MATH: $\fbox{\tt Calibrate}$ -->
<IMG
WIDTH="117" HEIGHT="27" ALIGN="BOTTOM" BORDER="0"
SRC="img1085.gif"
ALT="\fbox{\tt Calibrate}">.
The button
<!-- MATH: $\fbox{\tt
Edit}$ -->
<IMG
WIDTH="60" HEIGHT="27" ALIGN="BOTTOM" BORDER="0"
SRC="img1086.gif"
ALT="\fbox{\tt
Edit}">
allows to remove calibration lines from the dispersion solution
interactively, while
<!-- MATH: $\fbox{\tt Calibrate all}$ -->
<IMG
WIDTH="163" HEIGHT="27" ALIGN="BOTTOM" BORDER="0"
SRC="img1087.gif"
ALT="\fbox{\tt Calibrate all}">
estimates the dispersion
relation for the complete spectrum. The button
<!-- MATH: $\fbox{\tt Calibrate
twice}$ -->
<IMG
WIDTH="186" HEIGHT="27" ALIGN="BOTTOM" BORDER="0"
SRC="img1088.gif"
ALT="\fbox{\tt Calibrate
twice}">
performs a two-pass calibration.
<P>
Results can be checked with the buttons located at the bottom of the
Wavelength Calibration window.
<!-- MATH: $\fbox{\tt Dispersion}$ -->
<IMG
WIDTH="128" HEIGHT="32" ALIGN="BOTTOM" BORDER="0"
SRC="img1089.gif"
ALT="\fbox{\tt Dispersion}">
plots the
dispersion relation,
<!-- MATH: $\fbox{\tt Residuals}$ -->
<IMG
WIDTH="117" HEIGHT="27" ALIGN="BOTTOM" BORDER="0"
SRC="img1090.gif"
ALT="\fbox{\tt Residuals}">
plots the residuals,
<!-- MATH: $\fbox{\tt Spectrum}$ -->
<IMG
WIDTH="106" HEIGHT="32" ALIGN="BOTTOM" BORDER="0"
SRC="img1091.gif"
ALT="\fbox{\tt Spectrum}">
plots the lines identified during the calibration
process. These three functions are by default performed on the central
row of the spectrum. The button
<!-- MATH: $\fbox{\tt Line Shape}$ -->
<IMG
WIDTH="129" HEIGHT="32" ALIGN="BOTTOM" BORDER="0"
SRC="img1092.gif"
ALT="\fbox{\tt Line Shape}">
plots the
residuals as a function of the Y-position for a line selected in a
wavelength list.
<P>
<BR>
<DIV ALIGN="CENTER"><A NAME="fig:xwlc"> </A><A NAME="27970"> </A>
<TABLE WIDTH="50%">
<CAPTION><STRONG>Figure G.5:</STRONG>
Wavelength Calibration window</CAPTION>
<TR><TD></TD></TR>
</TABLE>
</DIV>
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<P>
<BR><HR>
<ADDRESS>
<I>Petra Nass</I>
<BR><I>1999-06-15</I>
</ADDRESS>
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