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The header parameters


Table 1: CLASS header parameters used to describe the frequency/velocity axes and their translation in this document.
CLASS name Unit Translation Notation
nchan -- Number of channel --
rchan -- Reference channel \ensuremath{i_{\ensuremath{\mathrm{0}}}}
restf MHz Tuned signal rest frequency \ensuremath{f_\ensuremath{\mathrm{tuned,sig}}^{\ensuremath{\mathrm{rest}}}}
image MHz Tuned image rest frequency \ensuremath{f_\ensuremath{\mathrm{tuned,ima}}^{\ensuremath{\mathrm{rest}}}}
fres MHz Observatory channel spacing \ensuremath{\delta \ensuremath{f_\ensuremath{\mathrm{}}^{\ensuremath{\mathrm{meas}}}}}
vres \ensuremath{  \ensuremath{\mathrm{km s^{-1}}}} Velocity channel spacing \ensuremath{\delta \ensuremath{v_{\ensuremath{\mathrm{}}}^{\ensuremath{\mathrm{meas}}}}}
voff \ensuremath{  \ensuremath{\mathrm{km s^{-1}}}} source systemic velocity \ensuremath{v_{\ensuremath{\mathrm{sys}}}^{\ensuremath{\mathrm{meas}}}}
doppler -- Doppler factor \ensuremath{d_{\ensuremath{\mathrm{sys}}}^{\ensuremath{\mathrm{meas}}}}

Table 1 describes the CLASS header parameters used to describe the frequency/velocity axes and their translation in this document. The signal and image frequency axis are given in the source (rest) frame by

\begin{displaymath}
\ensuremath{f_\ensuremath{\mathrm{sig}}^{\ensuremath{\mathr...
...emath{f_\ensuremath{\mathrm{}}^{\ensuremath{\mathrm{rest}}}}},
\end{displaymath} (75)

and
\begin{displaymath}
\ensuremath{f_\ensuremath{\mathrm{ima}}^{\ensuremath{\mathr...
...emath{f_\ensuremath{\mathrm{}}^{\ensuremath{\mathrm{rest}}}}},
\end{displaymath} (76)

with
\begin{displaymath}
\ensuremath{\delta \ensuremath{f_\ensuremath{\mathrm{}}^{\e...
...athrm{sys}}}}}^{\ensuremath{\mathrm{meas}}}}}{\ensuremath{c}},
\end{displaymath} (77)

where \ensuremath{\delta \ensuremath{f_\ensuremath{\mathrm{IF}}^{\ensuremath{\mathrm{meas}}}}} is the frequency channel spacing , and \ensuremath{v_{\ensuremath{\mathrm{\ensuremath{\mathrm{sys}}}}}^{\ensuremath{\mathrm{meas}}}} is the source systemic velocity in the measurement frame. The corresponding velocity axis in the measurement frame is thus given by
\begin{displaymath}
\ensuremath{v_{\ensuremath{\mathrm{}}}^{\ensuremath{\mathrm...
...{f_\ensuremath{\mathrm{tuned}}^{\ensuremath{\mathrm{rest}}}}}.
\end{displaymath} (78)


next up previous contents
Next: The MODIFY FREQUENCY command Up: CLASS implementation Previous: CLASS implementation   Contents
Gildas manager 2015-03-19