The user interface of the Elodie archive has been designed to be used either from a web browser or by a program. This latter feature, a fundamental principle of the Virtual Observatory, allows web-based services to transparently access the archive.
Accessing the catalogue of observations
Although this plain-text format is the only machine-oriented format now available for the catalogue, we may provide a tab-separated format (tsv) or VO_table format in the future.
To download the content of an URL on a user's computer, it is very natural to use a browser, such as Mozilla, Netscape or even Internet Explorer, but this is not the only solution. In practice, a browser is only one of the clients that may be used to access the Web. Other common clients are the so-called "crawlers" which can recursively download files from the web. A common one is wget, present on most recent Linux distributions (but several alternatives exist). In the following we will give examples with wget.
From a shell window, you can download the list of observations of Vega (see above) as:
wget "http://atlas.obs-hp.fr/elodie/E.cgi?&o=vega&a=t" -O vega.txt
Downloading FITS files directly
wget "http://atlas.obs-hp.fr/elodie/E.cgi?&c=i&o=elodie:19960502/0041&a=mime:application/x-fits" -O 19960502_0041.fits
In the URL above you recognize the unique identifier of a file in the archive. You may construct similar URLs for any file in the archive. If you are a familiar with a text editor (such as emacs, pico or nedit) and with Unix shell commands, you can readily write a procedure to download all the files you desire.
So, now you know how to easily download archive spectra in the s2d format. But you may wish instead the more easy-to-use reconnected, resampled spectra, or continuum normalized spectra. This is easy to do: just add the pipeline command to the URL. For example to get the resampled spectrum use:
wget "http://atlas.obs-hp.fr/elodie/E.cgi?&c=i&o=elodie:19960502/0041&z=wrs&a=mime:application/x-fits" -O 19960502_0041.fits
The pipeline command is the value of the z= parameter in the URL. You may analyze how the pipeline works by watching the customize menu, and then produce your own pipeline command. You can also read the documentation.
Useful shell scripts (NEW)
Accessing FITS files directly from astronomical packages
For example, by using the Pleinpot package, you may copy a remote file to a local disk file by typing:
copy "[http://atlas.obs-hp.fr/elodie/E.cgi?&c=i&o=elodie:19960502/0041&z=wrs&a=mime:application/x-fits]" 19960502_0041.fits
or plot a spectrum by typing:
hisvis "[http://atlas.obs-hp.fr/elodie/E.cgi?&c=i&o=elodie:19960502/0041&z=wrs&a=mime:application/x-fits]" @5
revised version: 27.05.08