Help (1st page) |
J2000 position |
Clicking on this button will allow the user to have access to an interactive page
where he/she will be able to reduce the spectrum on-line choosing
different parameters and performing different functions.
Please read the warning concerning resampling or
How does it work?
First in the "Processing functions: Data processing" section, the user chooses the parameters of a function that he/she wishes to execute THEN clicks on the button corresponding to the function.
Second in the "Processing functions: Data evaluation" section, the user chooses the type of output that he/she wishes to visualize or download by clicking on the button corresponding to the type.
Third in the "Output option" section, the user chooses the type of visualization.
On each click of the mouse, the command is registered in the "pipeline command" on bottom of the page. To submit the reduction request, the user should fourth click the submit buttom.
The Processing functions
There are three fields to be chosen in the processing functions section:
- The data calibration where the user chooses the spectrum resampled in wavelength (default case) or the s2d image. In the latter case, the user should not select any function from the data processing field.
- The data processing where the user chooses the functions and the related parameters to be processed.
Four functions can be processed, the "Resampling", "Flux calibration", "Flux normalisation" and "VSG" functions:
- The "Resampling" function allows the user to resample the
spectrum in wavelength by choosing the following parameters: the wavelength
interval in Angstrom [Wstart,Wend], the wavelength step (Wstep) and the
wavelength scale (linear or logarithmic). The command code is
wrs[1,Wstart,Wend,Wstep]. Warning: the
a restricted wavelength interval or the rebinning of the whole
spectrum will cause, at the present time, an indesirable interpolation
over the gaps in the spectrum containing any NaNs (bad CCD columns
or telluric lines).
- The "Flux calibration" function provides a flux calibration of the spectrum according to the choice of the user. Two choices are available: an "instrumental flux" calibration (i.e. corrected for detection effects as the flat-field) or a "continuum normalized flux" calibration. The command code is fca[1,ins] or fca[1,nor].
- The "Flux normalisation" function allows to normalise the spectrum at a given wavelength interval [Wstart,Wend]. The flux scale can be linear or logarithmic. The command code is fno[1,w,Wstart,Wend] for the linear scale and
and fno[2,w,Wstart,Wend] for the logarithmic scale.
- The "VSG" function gives the possibility to shift and/or broaden the lines according to the chosen parameters cz and sigma provided by the user in km/s. The command code is vsg[cz,sigma].
- The data evaluation where the user chooses the desired type of output which can be the "statistics" table (number of pixels and lines, mean flux and the RMS), the "header" list and/or the "spectrum". The command code is respectively for each type fs, fd and vs.
If the s2d image is selected in the data calibration field, the "statisctics" table and the "header" can be visualized and downloaded and the "spectrum" (s2d image) can only be downloaded.
The Output option
In the output option section, the user can choose the type of visualisation of the output chosen in
the "data evaluation" field. The different options are listed below:
HTML page & Download to a FITS file
Download to a FITS file
Download to a gzipped FITS file
Download to xview
Download to a FITS viewer
- The user should choose the parameters of a function BEFORE selecting the function (by clicking on the button associated to the function).
- The pipeline executes the commands following the order of the selections. Example: If the button "Display spectrum" (in the "data evaluation" section) is selected before the "Flux normalization" function (in the "Data processing" section), then the displayed spectrum will not be normalized, it will be associated to the functions called before (the default function is the resampled spectrum).
- A command in the "Data evaluation" section can be called more than once (example: the user could choose to view the default spectrum, select a function and view the new spectrum at the same time).
- If the same function in the "Data processing" section is called more than once with different parameters, the last parameters will be used for the process.
- If nothing happens after submitting a reduction request, this probably means that user forgot to choose the type of output given in section "Data evaluation".
- The user can type the commands codes directly in the "Pipeline command".
This archive is actively maintained. We thus welcome feedback from the user
to help us detect anomalies and improve the website.